Follow-up video that covers larger disc leverage and other questions this video may raise: th-cam.com/video/Ql9eYh31kTw/w-d-xo.html Support the channel by shopping through this link: amzn.to/3RIqU0u Become a Tuning Pro: hpcdmy.co/dr4a Brake the bank: amzn.to/3TLiqnj Patreon: www.patreon.com/d4a Never boil: amzn.to/3skjG58
7:08 that's not entirely true. motorcycle brakes need to dissipate a lot less power because of the lower overall weight. for this reason they are skinnier then care ones
I hope you're okay in Serbia. I know things are getting crazy over there ... and we all love you. Honestly, they're also going to get crazy here in the US, too ... The US is making a mess of the world. And many of us feel badly for what idiots our leaders have been. Blowing up NS 1 and half of 2?? (SMH)
Another reason why adding bigger brakes to your car won't necessarily improve braking performance, is if you cannot add wider tires to it - If the original brakes can already outperform the tires, you will need tires to improve braking performance, no matter what brake disc/pad you add to the system. And since a stock car has brakes designed specifically for the tires they ship the car with, the brakes are usually already strong enough to handle the tires, or even overpower them.
It was over 30 years ago that my physics professor used the formula for friction to tell me I was wrong in believing that wider tires provide more grip. I knew I was right but I couldn’t prove it to him. I very much appreciate the answer, even if it’s 30 years late. Ha. Thank you!
On a straight of a smooth surface probably doesn’t get you more grip, but wider tires mean more surface meaning higher limit when it comes to wear and heat, and irl grip isn’t just about stickiness it’s also about more space for the rubber to be stuck between rocks so it can literally push itself forward rather than using friction
I distinctly remember an old physics text book saying that wider or more tires don’t improve braking. I’m thinking “so why don’t race cars use bicycle tires to save weight?” This video was excellent.
@@jeremykoehnlein2158 ok it doesn’t improve braking BUT ya slow down faster bc of drag speed is effected also but… with much weight smaller tires grip harder per square inch there is a perfect width for every speed size weight combo… the drivers style can also be a difference also larger tires add more weight wich does help friction more so… yeah but. Anyways… just another way of saying….
If you are a design engineer you would know that this guy made a non point. I’ve never heard anybody claiming that “big brakes” make the initial cold stop shorter. On the contrary pretty much everyone with a sporty car knows that big brakes are for making repeated stops shorter, which they absolutely do. Also, even if he added an asterisk and said “big brakes don’t make your first stop shorter” well, he’d still be wrong. go ahead and mount bicycle brakes to your suv and tell me again about how brake size doesn’t matter. They should start running miata brakes on tractor trailer trucks now?
@@WithCarePlz The question is that most of the brakes that are used in cars are more than sufficient for the type of tire they use, it's not surprising that the ABS system exists, precisely to control braking, because if the brake works at its maximum limit it will most likely lock the wheel, which ends up making your braking distance worse. Finally, you ended up giving a very bad example, because obviously he is mentioning that the size of the brake does not matter, because he considers the stock car brakes, which have more than necessary performance to achieve the needed braking (it's even stupid saying bicycle brakes on an suv would not work, as obviously suv's don't come with bicycle brakes).
@@gamerbg294 thk you for the response to ozzy its ok to think outside the box but i think he went out to the pasture on that one. comparing apples to bananas 😁
As an expert (not trolling you) please read my comment above concerning the shape of the contact patch and tell me if you think it is correct. Oh never mind, I'll just cut and paste it here: Excellent presentation, as far as he went....see, one must also take into account the shape of the contact patch of the tire on the road. Skinny tires have an elongated (front to back) patch while wide tires have the opposite, which is a wider contact patch. This is critical on motorcycles especially. A thin contact patch will, because the tire is elastic, under hard/extreme friction will cause the tire to "ripple" making the bottom of the tire the shape of a sine wave. Reducing contact with the road while a wide tire with it's wider contact patch will deform much less, giving better "stiction". And worthy of note, no matter what size/shape of tire, the contact patch area remains the same. The shape will be different but the surface area contacting the ground will be the same. I wish he'd have added this information to the video as it is not a minor consideration but a major factor in handling and braking and acceleration. I give the video a thumbs up because everything he said was spot on correct, just incomplete so in school grade terms, an A minus. Please tell me if I am correct.
@@fireballxl-5748 I tend to agree with some of what you’re saying about contact patches. We disagree on his video. I feel that he is being very disingenuous. Bigger brakes are to prevent fading. Bigger brakes are for repeated stops as in performance driving which is why nearly every performance car sold has bigger brakes than the lower trim models. I feel like the internet just likes to whore themselves and clickbait things like this with catchy or juxtaposed nonsense such as “bigger brakes don’t stop better” Yeah. They do. Let me know when Ferraris stop coming with 16” carbon ceramic brakes and start coming with little huffy bicycle brakes instead since this guy and the internet say that “bigger brakes don’t help you stop better”
I always considered it this way: If your brakes can lock up, you already have more stopping power than you need. If you really want to stop, you need more rubber on the road. This is why ABS is a thing. Practically all modern car brakes are too strong for their purpose. As such, the means to improve them is to artificially weaken them so they don't defeat the tires capability.
@@tedmoss smaller brakes means smaller surface area means dissipate less heat, i mean what the fuck dude do you even watch the video before replaying to this dude?
I had a 1946 willys jeep. First year for civilian sales. You could stand on the brake pedal and still have to throw out an anchor to get it to stop quickly. 7" drums with a 302 ci Ford V8 didn't help an already bad situation. It go across a rice field. But wouldn't climb up the grass covered river levy. It would stop half the way up and slide backwards to the bottom. 35x12" wide tires are great. Just not for traction. Spelling edits. God I better start wearing my glasses.
Bigger brakes will usually have larger pistons and possibly a higher number of pistons, so the same hydraulic pressure applied to the brakes will actually result in a higher force pressing the pads to the rotors. But this of course means very little, when the tires themselves are unable to withstand the increased braking power. Upgrading both is the way to go. :)
It's not the amount of pistons but the area they press with matters (not the area pad at all, cannot be mistaken). Bigger amount of pistons usualy means they're smaller diameter pistons. Until You calculate the whole pistons' area, You cannot say 'more pistons result with a higher presssing force' as it's not precise. Plus - bigger rotors (bigger diameter) means higher torque applied with same force used, hence it's easier to stop a car. I don't know why it's not mentioned in this film, as it's very obvious.
bigger brake rotors and pads only spreads the braking friction out over a bigger area. Reducing heat accumulation and wear across the total area. You simply get longevity in extreme circumstances.
I have a small car workshop in Thailand. I explained a lot to my customers, as you said. If they use the car in normal conditions, e.g., in everyday life. It's optional to upgrade the brake if they want, but just OEM. It's entirely enough. Investing more money in new tires is a better option. It's the fence between the car and the street. For example, most cars didn't upgrade their brakes and could drive on the German autobahn safely without a speed limit. That means the OEM specification it's enough. You're very professional from the practical to the theoretical view. With suitable examples, good explanations, and easy listening. That's super cool!
As an Engineer, I love how you explain things with formula and science but simplifies the theories so people without the technical knowledge can understand. Also as I car guy, I love how things I learned in University have application to my hobby. Win, win in my books.
Well then this is not the video to learn from. The whole point of bigger brakes is that they don't lock up and have less friction. Which contradicts the point he's trying to make. Bigger brakes are effective by not locking up as easily. Because when they lock-up (from too much friction) your braking is only as good as the sliding rubber (tire) on the concrete. At the end of the day force of pushing the brake pads on the disk is roughly the same. But smaller brakes have less surface area resulting in more friction we don't want as it leads to locking up your brakes. It's still a useful video from physics standpoint, but certainly not from automotive. PS. Cars have ABS yes, but your braking will still be far less effective if it has to kick in more than it would have otherwise.
Totally agree with what you say. Where the bigger breaks bring benefits is that they have a higher thermal mass to absorb and then dissipate the large and repetitive energy of breaking. I fit upgraded two piece breaks, pads, and very high temp fluid in the STI. The result was less fade and shorter stopping distances. A side benefit was lighter disk assemblies as well as forged rims for a loss of near 9Kg per corner. Larger and better gripping tires tend to bring with them the requirement of up graded breaking components.
as someone working in a dealership, i see this quite often. people want good brakes, such as ate, brembo, but if you ask them about tires they often pick the cheap options because the actually goods ones are too "expensive". so you want good brakes while also dont?
Bigger brakes can hold more heat before overheating and they dissipate heat faster. Putting tiny brakes on a race car may lock up the tires, but they will overheat instantly. Also a larger rotor will give the calliper more leverage to stop the wheel. Anyway I think that unless your brakes are tiny, or you do hard tracking with a powerful car, a simple pad upgrade is all you need.
Great video. But don’t larger diameter rotors place the caliper slightly farther from the center of the wheel which allows the caliper to have a greater moment arm which puts more torque on the wheel than does a caliper on a smaller diameter rotor? If smaller diameter rotors performed just as well as larger diameter rotors, sports cars would use smaller rotors to save weight. You might also want to do a video on multi piston calipers and two piece rotors. My 2003 RS6 has 8 piston front calipers and huge, two piece rotors and stops in less distance than any other car I have ever owned.
@@glenwoodriverresidentsgrou136 If your small brakes can lock up the tires, the only thing bigger brakes will give you is better resistance to heat fading. More metal = more thermal mass therefore, harder to overheat. However you’re right, if you have really sticky and wide tires you need big brakes to use them to their full potential. Race cars have a ton of grip and therefore require big brakes to max out the braking grip. Tire grip determines stopping distance, and your brakes only need to be able lock them up to get the most benefit (which many “small” brakes can do even to tires like PS4S etc.). So at that point, bigger brakes only helps reduce heat fade by increasing mass and cooling area. My gti has relatively small brakes but it can lock up warmed up 245 Pilot sport 4s pretty easily. This means that my one-time stopping distance wouldn’t decrease with larger brakes, but it would be more consistent around a track with multiple braking zones. If I fit some really sticky tires the brakes probably wouldn’t be able to lock them up anymore at which point I’d indeed need bigger brakes.
It isn't that you expect a big brake kit to stop you faster. I know better than that. If your brakes are strong enough to lock up your tires, then you're not going to gain anything with a bigger brake kit. What you will gain in most cases is reduced fade. Both by additional Mass for the Heat to go into, and greater heat dissipation assuming that the disc is reasonably designed. In some cases, these aftermarket discs will perform less well initially. Because they're designed to be used at the edge of performance and really give their best performance once they are hot and the braking compound has chosen to work with that. When the brakes are still cold, you may have a stiff or slick feel to it like it's not braking very well at all. I have a 2021 Mazda3 turbo which I bought at the very end of 2021. 2282 I put 54000 miles on the car, I drive a lot. And it is through the North Georgia Mountains so it's a lot of curvy roads with long steep grades. Do not get me wrong. I love my little car. For daily driver it is awesome. The tiniest little GT car ever. It will effortlessly hold 90 miles an hour while getting 28 miles to the gallon, it has plenty of power for passing and can squirt up and down those mountains. But. And it's a big but. The front brakes are inadequate for truly spirited driving. In less than 3 Mi coming down Brasstown Bald oh, I was able to get the brakes so hot that breaking Effectiveness was reduced by 80 to 90%. Toward the end I was actually a bit concerned, having to use engine braking and sudden darting movements to get the car to slide a bit to scrub speed. In Daily driving, I've never had a problem with it. But I have chosen to get the corksport big brake kit oh, and the next time I'm due to buy tires, I'll be swapping out the tires, wheels & installing the brake kit. For now, I've chosen a high-temperature compound for my brake pads. It does mean braking is a little bit subpar when the discs are cold. But far from dangerous. And as the discs get hot, fade is greatly reduced.
I think that the reason is much simpler. Most brakes are already able to lock up the wheels while braking so pressure increase won't help, because the wheel can be already locked up with smaller brakes (that is also why every new car has ABS). This means that breaking performance for most cars isn't brake pressure limited, bud tire grip limited. Larger tires will have more grip and more grip means more friction, which improves braking performance.
Some cars have OEM brakes that are just enough to reach the ABS threshold on the OEM tires. I have a car that was unable to reach the ABS threshold on smooth, clean, dry pavement after I put on stickier rubber. My solution was pads with a higher coefficient of friction than the OEM pads, and it solved the problem very well. I suppose larger diameter disks would have solved the problem too, but I didn't want the extra unsprung and rotating mass. Replacing the pads was an easier, less expensive fix also.
@@xtnuser5338 Yup similar here, I think tire technology has improved enough over the past 15 years that the OEM brakes on my car no longer are able to reach the ABS threshold on smooth dry tarmac. Given that I also want to fit slightly wider tires because the OEM fit is really slightly too small for the rim for some reason, I'll definitely be upgrading the brakes too when I can.
TRUE, Until the second hard application and the small factory brakes are fading from overheating .. there's far more to brakes than presented in this video
@@jkoorts At some point, the grip is so much that you need more stopping torque to lock it up with abs. That could be accomplished with larger diameter rotors, or it could be accomplished with better brake pads alone. That's how I solved the problem. I installed much stickier tires, and could no longer trigger ABS on smooth, dry pavement. I understand the physics, and knew that I could use more stopping torque, but also knew that I did NOT need more heat management capacity. So I selected pads with a proportionately higher coefficient of friction to try matching them to the increased tire grip. This solution worked perfectly, while being way less trouble and way less cost than installing a big brake kit.
That's short of right. Bigger brake rotors and bigger (more pistons) calipers to go along with wider tires will get you better/shorter braking distances. Just because you get wider tires doesn't necessarily mean you'll stop faster, because if your smaller brakes don't have the stopping power to go along the the extra grip from wider tires, your still losing out of stopping distance, plus the smaller brakes heat up faster causing brake fade which could ruin your day and your car.
That is correct, the thing is bigger brakes are more efficient in dissipating heat making braking more consistent and predictable. Altho without the grip from better tires u will only end up locking up ur tires which can be dangerous in emergency braking situations...it is why brakes and tires are ideally upgraded at the same time
@@bluegizmo1983 exactly. It all depends on what the weakest link is. Bigger brakes show the tires weaknesses more. But the biggest benefits are heat dissipation and consistency, and lets not ignore the obvious elephant in the room.... They look cool.
I feel like you could do a more advanced video on brakes too. Such as larger brakes having a centre of braking pressure further from the wheel hub so you can brake harder with less force. Or even talking about how pads warp and why multi piston brakes have an advantage etc etc. love the vids ❤
@@wmgilliland2582 yeah I know, but higher brake pressure starts to warp pads and heat them unevenly which causes the brake fade to come on sooner. Nothings absolutely rigid so the larger brakes are more than simply better cooling.
@@abbottboyaustin I'm with you Austin. An obvious example is all the superbikes with the huge diameter rotors and a small pad contact area.. The length of the 'lever' has a huge effect etc...
For sure. The initial explanation in the video is wrong. Bigger rotors = more leverage = more brake power More piston area on the caliper = more force = more friction = more brake power The stopping distance do not change cause the stock brakes already have more than enough power to lock the wheels, so using a good ABS system you are already performing the minimal brake distance on regular cars.
Great video. I actually asked a friend of mine when I learned about this formula almost 10 years ago. He's an automotive engineer, but he couldn't really explain it and shrugged saying it's experimental evidence that did not align with the mathematical formula. I of course already figured it out by now, but I would have loved your explanation back then!
I always wondered why tire width matters but the formula says otherwise. After watching your "Why are Front Brakes Larger than Rear Ones? Brake Bias Explained" I was really wondering. Thank you for explaining all the complexities and how it applies in reality reguarding tire width. It is hard to find good information like this. Your explanations are excellent! Thank you.
Before vid, my understanding of big brakes was they allow better cooling to allow better braking over time. Larger area allows more heat transfer which means when you have to consistently hard brake (track driving) you are less likely to overheat and experience brake fade
This is true, and this is also why cross drilled rotors are a detriment to braking performance on the track. You are literally removing mass from your brake rotors for no advantage what-so-ever. Ideally, you want to find the sweet spot between mass and heat absorption. Drilled rotors add no benefit in this area over a set of slightly smaller solid rotors, but they do cause problems with stress fracturing, and premature pad wear. If you go to a club race, pay attention to the kinds of rotors all the top guys a running. I guarantee they will be solid rotors. (The above is not meant to apply to carbon rotors.)
@@operator0 " Larger area allows more heat transfer" this is not the main reason to increase pads size. You can increase heat transfer without increasing pads size - better ventilation, increasing disks size without increasing break pads size etc. Main reason - bigger pads wear slower, as there is more material to wear.
@@bumbarabun I repeat, not necessarily. If the pads are wearing at the same rate, they will wear out just as quickly. Look, imagine the surface area of your pads was the tip of a marker pen. If you draw with that marker pen it will run out eventually. If you double the contact area by taping 2 marker pens together, they will still run out at the same time. You have double the contact area but you're still using it at the same rate. Try it! It won't be exactly the same, there are other factors involved that can make a difference, but that's why bigger pads won't necessarily stop you any sooner.
Don't forget bigger breaks offer better leverage to stop the wheel :) it's simple though as somebody who grew up loving every single racing sim. if you can lockup your wheels then you need better / wider tires. If you can't, you need better brakes. that's all you really need to know from a maximizing performance standpoint. rinse and repeat until you have the breaking performance you desire.
I just upgraded my brakes from tiny single piston callipers and small rotors to larger twin piston callipers and much larger rotors! the smaller brakes struggled to stop with consistency and I found it easy to have less than desired stopping abilities and harder applications of the brakes would result in lockup’s now with much more braking capability the consistency is much better and although over braking can result in a locking wheel it’s much easier to have complete control and feel the limit of traction with brakes that aren’t at the limit of thermal absorbing
Really depends on what you're locking. And that comes down to mechanical grip. Weight transfer left to right and rear to front all play a part in overloading the tire.
Exactly, larger rotors rarely have significantly larger pads… they have a larger diameter, resulting in better leverage, needing less force on the pads to equal the stopping power… which reduces friction and heat as well.
Wow!!! The way that you differentiate between friction of various materials--and wet vs dry--was fantastic! And your illustrations were excellently suited to the topic at hand while keeping things interesting and fun to watch! Well done, Sir! I'm looking forward to learning more about tires in the future--high vs low profile, soft vs hard compound, wide vs narrow, summer vs winter, etc. Keep up the great work!
I read an article on this topic years ago and having this mental model of how tires create grip has provided so much benefit. Once you understand the concept you can derive all sorts of other things, some of which you talked about. For example, knowing that a tire's grip doesn't scale linearly with the amount of force with which it is pressed into the road you can see why things like low profile tires can help keep more of the rubber in contact with the road due to reduced deformation under load. It also helps explain how things like camber, roll stiffness and tire pressure all contribute to maximizing the grip in a given situation (when a car is cornering the grip lost on the inside is greater than the grip gained on the outside so all of the painstaking setup work on a racecar is ultimately about trying to create the least deviation in tire load across all points of contact since the best possible grip is when all parts of all tires are as evenly loaded as possible.)
And there's also different friction coefficient for sliding and rolling contact... rolling rubber on road is 1, sliding rubber on road is .5.... rolling rubber on wet road is .5, sliding was .25... that one stuck with me.
@@ChrisMah You also have to figure in the tire compound itself... 'sticky' race compounds you can dig a fingernail into will damn near work on a vertical surface, where as your harder compounds won't stick so well, but the tire will last 50,000 miles and probably get great gas mileage too... where the race tire will burn out in 1000 or 1500 miles, and really suck for mileage going down the road. Like many things, it's a compromise as to which properties your desire and which ones do not matter for your application.
@@kleetus92 Yes, good point. I’m even amazed how sticky some of these 200 tread wear “street” tires can be these days even although still nothing like soft race rubber.
Wow!!! Absolutely fantastic vid!!!! I have experienced brake failure on 2 of my fat tire electric bikes. I have two bike brands that have failed on steep hills: 1) The RadRover 5 and 2) the Juiced Rip Current S. Both bikes have 4" fat tires and have under designed brakes systems to handle the heat issues of braking on steep hills. This is a big safety issue for these and other Ebike brands. Also both bikes take a lot of maintenance, because their brakes are under designed. I only get about 1,000 miles on a set of brake pads on these bikes. Compare this with my Lexus CT200H brakes after 115,000 miles: Zero brake maintenance and the brakes pads are only 50% worn. I really enjoy your real life engineering vids. Thanks, an aircraft tool designer from Seattle.
Absolutely correct that increased surface area for brakes does not mean more friction, but mean effective radius of the braking surface will affect the leverage the brakes have and affect stopping power. So a larger diameter rotor will generally have a larger mean effective radius and more stopping power. Since most vehicles brakes can overcome the grip of the tires anyway, though, the most notable benefit of larger brakes is the heat dissipation. Ignoring mean effective radius of the brake rotor when calculating stopping power is incorrect though.
Bigger surface area on pads usually means bigger rotors. This means more moment on the axle so whilst the friction force may stay the same, you get more stopping power (or less heat) for the same force applied to the pads. Edit: Not less heat (generated). Typing without thinking.
@Andrew Crews Exact, the heat you generate will be the same but there is more thermal mass, there is also more surface area to dissipate heat to the air use big brake kits if you start feeling squishy brakes if you just wanna increase braking distance, upgrade to better master cylinder and better stickier brake pad compounds
This should have been covered in the video, but braking force is generally not limited by the amount of pressure you can put on the pad. With brake boosters you can have any force you want pretty much. The main reason you don't get better braking performance with bigger brakes is because you are tire limited anyway. Even normal cars with pitiful brakes have more than enough clamping force to overcome the friction of the tires (hence why ABS exists). So again, the only reason to get bigger brakes is heat management as stated in the video.
@@RENO_K Few people in this comment thread understood the video. If your brakes produce enough pressure to lock up / engage ABS, the ONLY way you can decrease braking distance is if you decrease vehicle weight or get wider / stickier tires. Bigger rotors, better brake pads, etc will never decrease braking distance.
Really well explained ! Glad you added one of the downsides to fitting wider tyres - aquaplaning, a very nasty possibility in heavy rain and it's a given that you'll burn more fuel - real life is full of compromises !!
For motorcycles, putting holes in brake disks improves wet-weather initial (first couple of revolutions once brakes are applied) performance. Slots do the same, maybe better. It also reduces unsprung weight, but probably not enough to matter. Bikes have comparatively little 'sprung' weight, so the sprung / unsprung ratio matters more than it does for cars. One of the best handling mods I ever did for my Ducatis was to swap stock wheels for exactly-the-same-size Marchesini magnesium ones. Same tire models and sizes, big difference in handling. I used to set up bike suspensions for the track, and this was a bigger difference than changing spring rates, preload, or damping.
The drilled holes are functionally allowing more airflow and hence cooling. The purpose of the slot it to have an edge wipe the pad removing debris and ever so slightly shaving the pad for contact area while chasing the gasses away. That is why it has to go in the proper direction.
I've had this argument with several people in the past. Fact is, stock brakes (at least since the 1990s) are limited by the traction of your tyres. They will apply the naximum amount of braking that physics will allow at least 5 times in a row from a very high speed. Therefore, your street car doesn't need upgraded brakes unless you intend on braking the law. Regardless of how much power it has. If you're going to the track, then upgraded brakes can help. Generally you'll get by with just track pads.
@@robair67 the law of "I've driven lots of cars on race tracks with stock brakes all the way up to retired V8 Supercars and know what I'm talking about"
@@robair67 I'm not saying you SHOULDN'T upgrade your brakes. My point is, people go from stock brakes with regular pads and think they need to change calipers on road cars. Then when they do and they feel better they think they have improved the brakes. But its just the pad. You can get the same pedal feel and performance from stock calipers by upgrading to a track pad. Changing calipers means you also need to balance your master cylinder size and fluid capacity and people don't take this account and ruin their brake bias and therefore vehicle safety. If you're going to change braking components, it needs to be a full system. Otherwise, just use a slotted rotor to keep the gasses off the pad, and run a high temp fluid and pad and you'll get exceptional performance and great pedal feel. Generally going from a large single piston to smaller multi piston setup doesn't actually give you any more surface area anyway. It just distributes the pressure more evenly across the pad and is more for temperature and pad wear than actual braking force.
@@1one3_Racing some years ago I went through a 10 year long phase of driving only front wheel drive cars, when on the road. It was no fun...except for left foot braking! However, it really eats through front pads (and discs) and at one stage my standard compound pads had worn about 3 to 4mm diagonals on the floating calipers. The sliders and pistons were still serviceable and within tolerances! A change to 1144 pads meant better front braking and therefore an increase in line pressure was needed at the rear (drum brakes- 1.6 205) which was achieved by deleting the load valve. The balance was absolutely amazing, even at motorway speeds. This car ended up exclusively a circuit car and the brakes just couldn't keep up. So your explanation definitely bears out my experience with that car. And finally, I may have broken a few statutes and acts of the ministry of transport (!) but I am bound by Common Law, not corporation law!
One Thing you didn't mention is that MU can go above 1 on tire and brake pads. When a track surface is coated with rubber, it's more in the realm of adhesion and suction than friction only. Same with brake pads, your surface area falls on it's face as they require break in which is not only cleaning up the surface, but also adding material to the disc that creates and adhesion layer more than a friction layer. That is why it's important to run brakes in their temperature range where they actually transfer their material to the mating disc.
Excellent video, one point you did not mention is that the rubber mixture can be changed as well, so you can make a wider tire out of softer rubber which will increase its adhesive properties while lasting a similar comparable distance than the stiffer narrower tire.... so many parameters to play with :-)
I think this was a great explanation of the subject. Especially for understanding the underlying concepts. But I would have added the equation of breaking moment which is dependent on the friction force and the moment arm, which in this case is the radius of the applied normal force on the brake pad. Just to show that the friction force and brake diameter are indeed coupled, even though the heat transfer is the actual thing to solve with brake systems.
In the interests of completeness larger diameter discs do give greater breaking force everything else being equal. The reason being the braking force is at a greater average radius from the wheel axis hence increasing the braking torque. This only means less hydraulic pressure is needed. However in practice the hydraulic pressure is not the limiting factor to rate of vehicle deceleration hence none of this changes the premise of this video. Another great video thanks...
All in all, a good explanation, there are nuances that can turn this in to a multi hour lecture. My practical experience is that I use stock brake rotors and calibers with aggressive pads for racing. Even up to 25 hour endurance races. In a light car (Miata) with the biggest and good tires (Hoosiers R7) that fit within the fenders, I still have more brakes than tires and have never had issues with brake fade. But they do not look as cool as a big brake kit! Keep the videos coming.
interesting. I also race a Mazda (a mazdaspeed 3), and I've upgraded my rotors and pads and tires. I've noticed significant reductions in brake fade since making the change. And I'm only doing hpdes.
@@3MZFE Not sure about the details of your MazdaSpeed3 but looks up the weight and the internet reports around 3,200 LBS without driver. If you drive your HPDE car on the street, then would assume you are using less aggressive pads. My first gen Miata is under 2,200 LBS with driver across the scales at an end of a race (per the rules for the class I race in). I would guess the extra 1,000 + LBS makes a difference. I don't even have to use expensive brake fluid as long as I keep the cheep store brand DOT3 fluid fresh. I do use aggressive pads which requires brake pressure modulation to avoid flat spotting the tires.
I run stock sized rotors in my Exige (2025-lbs with me in it), because I didn't want the extra unsprung, rotating mass of larger ones. (Also I am using 1" less wheel diameters than OEM so there isn't a lot of extra room.) But while the OEM pads were enough for the OEM tires...once I added stickier rubber, they weren't good enough. So I added Pagid RS42 pads and it brought the ratio of pedal pressure to stopping power right back up to what I liked. (There are even more aggressive pads of course, but the RS42 still has decent low-temperature operation and rotor wear rate, and I street drive it occasionally so I think they were the best choice for me.) I run Motul 600 fluid even though I probably don't need to, just for the peace of mind. People always ask me if my brakes need repair work, because they squeal a bit when street driven. No. No they definitely do not. I haven't run with ANY other production street legal car on DOT tires that will out-brake it in my sixteen years of doing HPDE.
Thank you sooo much for making a video in response to my comment.This question has been in my mind for years and now I got an answer from one of my favourite TH-camrs.Your channel is brilliant and deserves more views,keep going, great work!
Excellent presentation, as far as he went....see, one must also take into account the shape of the contact patch of the tire on the road. Skinny tires have an elongated (front to back) patch while wide tires have the opposite, which is a wider contact patch. This is critical on motorcycles especially. A thin contact patch will, because the tire is elastic, under hard/extreme friction will cause the tire to "ripple" making the bottom of the tire the shape of a sine wave. Reducing contact with the road while a wide tire with it's wider contact patch will deform much less, giving better "stiction". And worthy of note, no matter what size/shape of tire, the contact patch area remains the same. The shape will be different but the surface area contacting the ground will be the same. I wish he'd have added this information to the video as it is not a minor consideration but a major factor in handling and braking and acceleration. I give the video a thumbs up because everything he said was spot on correct, just incomplete so in school grade terms, an A minus.
Yes, its amazing the number of people who believe that a 2X wider tire will have a 2X larger contact patch area! Even the purported engineers are getting it wrong!
I've never wanted to upgrade to larger rotors for increased stopping power. I've always (intuitively I guess) known that the purpose was to have greater surface area to increase heat dissipation to reduce the chances of degradation of stopping power due to overheating and/or damage. All brakes can lock up your tires (assuming no anti-lock) so they all have plenty of force necessary to stop you as quick as possible. Losing traction on the road directly affects stopping distance. Maintaining traction is how you stop faster.
Tyre pressure has just as an important role to play. I must say, my car with a 325mm rotor is a better & more sure footed stopping car than with the 298mm rotor both on a 245 40 18 tyre/rim @40psi operating temp. Thankyou for another excellent series.
One thing I think u forget to mention is bigger brakes (rotor) will have longer arm of force, thus creating more brake torque. However, for most modern production cars, the factory brake is sufficient and can break the traction of tires during heavy braking. Simply upgrading the brake may not shorten the brake distance during heavy braking. I remember there was a test by a media in China. They compared two Civics, one with factory brakes and the other have high performance Endless BBK. After initial tests, the one with Endless actually performs slightly worse than the factory one (likely due to heavier suspension weight from the brake kit). However, what makes bbk stand out is repeated braking. The factory brakes experience serious brake fade after multiple brake tests but the Endless BBK still performs just fine.
The upgraded pads sometimes need to be hot to work best. That's been known for years. And yes the continue to stop better with more use instead of fading like oem pads
@@danc2014 It really depends on the car, mostly the weight of the car. I've never experienced brake fade in my Datsun 510 and trust me, I've driven the piss out of it. There is absolutely no reason to "upgrade" your brakes from stock when you have a car that stops from 60mph in 70 feet.
When it comes to larger breaks for track use one factor wasn't mentioned. Modulation. With larger rotors creating more leverage modulation at the limit of traction becomes much easier. Breaking on the limit is where a lot of time can be made up followed by trail breaking through a corner which both take finesse and larger rotors along with pads\calipers make this much easier. Great videos!
you are saying that the further the BRAKE pad is from the axle, the less force is required to generate the same BRAKING torque on the axle? If that is desirable, then why are racing cars not set up to reduce the force required to actuate the BRAKES to a minimum? In fact we find that GT3 drivers expressed that BRAKE pedal stiffness was set largely by personal preference when its adjustment was possible.
@@joelambert7128 I never said less force was required. With smaller rotors the window between maximum braking before lockup and complete lockup is smaller meaning your modulation on the edge is harder to control. With larger ones that window is bigger and easier to modulate on the edge of traction.
That's for motorcycles. Not cars. You have four wheels. And you control all four brakes with one foot. That's why ABS is allowed in professional racing. Cos it's the same foot your ancestors used to ride a horse or drive a horse cart. You don't have a high tech foot that can control brakes on a car, it won't happen, get over it, whatever you think you have, you don't, without ABS, a motorcycle will leave you in the dust
This is what I’ve been telling people. Suspension and tires are better brake upgrades than brakes themselves. Now I know the science to back it up! Thank you!
Suspension and tires upgrade is not better way because stock brakes with upgraded suspension and tires will burn out very fast and you may loose brakes completely, so this is very dangerous upgrade. When you upgrade brakes only then braking performance will increase and burning out brakes will be even less likely then on stock setup. This is total BS that by upgrading brakes alone will not increase braking efficiency. Enlarging tires alone beyond manufacture specs will generate higher ware on suspension. Even replacing old brakes with new parts is increasing braking performance, not mentioning about installing larger ones It is true that if you want to capitalize on brakes upgrade suspension and tires should be upgraded too, but safer way is to upgrade brakes first.
Don't believe this video. It's not really accurate. If your brakes won't "lock up" the wheels and cause the tires to skid... then you could do with "better" brakes, unless your wheels are very narrow and skid very easily... in which case you THEN need wider tires. This video is an over-complication of a simple concept and the fundamental premise isn't correct.
@@sawomirmiszczak134 You mean the more stupid way is to upgrade brakes first because you will activate ABS even with the stock brakes. With larger brakes and everything else standard, you would only activate ABS faster.
@@jkliao6486 I was talking about heat, with better tires and suspension stock brakes would over heat very quickly, and this may lead to dangerous reduction of braking force. And i say it again, even with replaced braking discs and pads for new you can gain couple meters comparing to old/used pads and discs. So the stupid way is to think that upgrading brakes won't do anything, it will.
@@sawomirmiszczak134 It will NOT. If you don't have the grip on your tires, you can't even overheat the brake. Your tires would give up first. Which is why you never upgrade your brake alone to improve your lap time. If you are talking about daily driving, then it's even more pointless to upgrade brake with stock tires and suspension. As for worn pads, that's about proper vehicle maintenance. When sth wears down, you replace them. Just like tires, engine oil, washer fluid and even fuel, you run out of that, you replace that on your car. You don't have to actively replacing your new brake pads with bigger ones to improve your vehicle stopping power. It won't do anything AT ALL. If anything, you probably reduce your vehicle's stopping power because now you need bigger alloy wheels that are much heavier. The next thing you know, your vehicle becomes a flat tire collector with those low profile tires.
It should be noted that increasing the friction of the tires (eg: wider tires, stickier rubber) will increase the amount of heat being generated at maximum braking as the brakes can withstand more force before lockup.
I love the amount of reserch you must do for your videos and the way you can present the facts in a form that regular guys can understand. The fact is that most modern vehicles equipped with EBD and ABS, the ABS kicks in if you stamp on the brake pedal so it obvious the tyres are the limiting factor for single brake applications. If you are a track guy or towing heavy loads you obviously benefit from better heat dissapation, the other factor is that larger calipers and discs makes braking more predictable with better "feel" over a wider temperature range. You have remember that many race car series do not allow ABS so this is important. The other factor is that most regular vehicles have single piston, sliding calipers for cost reasons, whereas "perfomance" brakes have multiple opposing pistons to provide higher force and a more consistent brake pad application. One question, is it fact or fiction that you can boil the brake fulid in the calipers to a point where you are relying on compressible brake gas rather than hydraulic / liquid brake fluid? I experienced this in some of my older cars where the pedal went to the floor after some serious repeated braking but recovered fine once things had cooled down.
Yup. F1 cars have smaller breaks that some would expect. But the cars have much larger tires and their breaks can tolerate much more friction and heat. I love your videos by the way. ✌️
So true F1 priorice tyre wall to been used as suspension than bigger brakes. I'm pretty sure they know what they're doing. And before regulations the brakes were the smallest possible without compromising to get more tyre deformation benefits.
That's why they makes sense on motorcycles, particularly at the front, since that's the brake you use more often. I remember when I had a two-stroke 125 sportsbike, going flat out on downhill twisted roads I had to use the rear brake to compensate for the almost non-existent engine break. Sometimes after 10 or more miles downhill, I had to stop for a couple of minutes to let the rear break cool because it started to feel as if it generated friction without breaking. Despite breaking most of the time with the 320mm floating front disk, the 220mm one caliper rear disc was the one affected, never had a problem with the front one, not even at the race track.
im glad you brought that up. I had the same issue when rallying my sports cars down hills. When your materials heat up they expand. the rotor expands as well as your pads expand. even the caliper expands. They dont expand a lot, mind you, but eventually as everything heats up and expands, its as you said, you are braking without actually braking. by stopping for a few minutes and letting the brakes cool off, they contract back to normal size.
Well on track those 30hp street 125’s are so heavy that we actually destroy the front brake a lot on stop&go types track. Lots of front discs we see deeply cracking between cooling drills.
@@Dstructeur1 these guys might have a better rotor for you, sorry youtube dont allow links anymore it seems. Look up brake tech. They make great aftermarket motorcycle rotors
@@blue03r6 We mostly use Brembo’s series Oro discs, which are among the bests available, so I doubt there really is a fix to this inconvenience sadly. Single front disc is a weak point by itself, but 2 discs setups are much heavier and would level down actual bike performance. Maybe the 4-small rotors from Beringer for front end might be a fix, but would still be hard/impossible to have homologated in any racing division and would still weight a bit more than acceptable although reducing inertia induced by 2 huge rotors.
@@Dstructeur1 those brembo's are solid all around. look up the cobraMX discs from braketech. there cut out all over to make them super light. they look like they'd weigh half of that brembo
Interesting. I upgraded my rotors from 270 to 290mm, same caliper, same pads and same tyres. Stopping distance when from about 48m to 35m, cold and both and similar hot. Interestingly the force on the pedal to get the same stoppage went down a lot and the band from slowing to locking widened, so the smaller rotors either didn't stop good or fully locked with little threshold on pedal force between the 2. The larger diameter rotors widened this a lot so that I can modulate the pedal much easier without the fear of instant lock up in a panic stop. I could be wrong but this would be the mechanical lever advantage increase? Like going from pedal back brakes on a BMX to conventional rim caliper type. My upgrade is a very minor bolt on one. It's far more common to go for the twin piston setup for the front from the later models. It's pad is more than twice the size, rotor is 296mm so pretty much the same diameter. The thickness goes from 23mm to 28mm. This upgrade makes an enormous difference cold and even more so hot. I think there is more to it than just heat dissipation. Probably leverage, heat, caliper rigidity, pad pressure uniformity, glazing, rotor distortion etc...
What probably happened is that your new rotors lock the wheels faster. While both locked the wheels, let's say the new brakes lock them 0.5 seconds faster, that results in reduced braking distances because optimal deceleration is reached faster
@@StragTacGaming you're wrong. It's also a common misconception of "why upgrade your brakes I can lock up my wheels fine..." Locking brakes is the worst way to slow down. Peak braking efficiency is where you can apply the most braking pressure while not skidding. Bigger brakes have more leverage so require less pedal effort to apply braking force. This means it's easier to ride the limit of traction. This is also why "wide tyres help braking" because you can push harder before it skids. A bigger brake on the wider tyre will still brake better. You can look at it as stock brakes are a 3 position switch - off/slowing/emergency and big brakes are a 7 position switch and you'll understand the control you have
@@JackoTJK My comment was considering an ABS-equipped car. When you are able to lock the wheels earlier, the ABS can work to modulate the braking pressure earlier. The best deceleration is provided under slight lock (ABS does this perfectly), just like how the best acceleration is provided under slight slip, and having a bit of slip on a launch will always be faster than having 0 slip
@@StragTacGaming ABS is less efficient than manually modulating if you have any skill which is why most racecars don't have ABS. But. It doesn't matter. ABS works by taking pressure out of the brakes regardless of pedal position when it detects a lockup. Better brakes means it will work less because they are working better so you're less likely to lock them up. You can push closer to the limit with only the better pedal feel. I'll say it again. Good brakes does NOT mean they lock up. They are in fact the WORST brakes if you did a side by side stopping distance comparison. The best brakes give more braking with less pedal effort but have good feel from barely touching to full blown emergency
@@JackoTJK ABS is better than threshold braking. It's a common misconception that you can brake better than ABS. See Engineering Explained's video about it: th-cam.com/video/G-GEUkiMuLk/w-d-xo.html And race cars do in fact have ABS. For example GT3 cars. Only series like F1 have ABS banned because it makes it too easy
Based on my experience with motorcycles, I figured the answer was that your brakes are going to be able to lock up the wheels anyway, so the contact patch was the limiting factor
There is a direct correlation between additional tire patch width and increased grip (all 4 directions) - all other things being equal. This correlation gives you between 20% and 60% additional grip for additional tire patch. The example I use is going from a 245 section width tire to a 275 will increase tire patch by about 12%, take that and multiply that times 40% (the average) and you are getting about 5% more grip. That 5% may seem minor, but if your car stops from 60mph in 110 feet, you just dropped it to 105; if your car corners at .95g, now it should be about 1.00g. I've seen too many articles and videos of people buying/upgrading cars with carbon ceramic brake rotors and bitching about how their car stops the same as the ones with the iron rotors, which proves that tire patch is more important that brake rotor material, number of pistons, or size of your rotors. Another item people overlook too often is that front brakes provide about 70% of a car's stopping power due to weight transfer during braking - upgrading rear brakes (unless they are tiny or drums), does almost nothing to shorten braking distances (even in rear engine cars). So when someone has 15" brakes all around, the rears are just for looks, the 13" would be more than adequate. Lastly, most front engine cars benefit from a "square" tire setup (same size on all 4 corners) due to having 50% or more weight up front. BMW for years liked to stagger the tire sizes, even though their cars were 50:50 weight biased give or take. 225/255 was very common and hurt braking and cornering quite a bit - anyone who raced these cars always ran a 255 up front to balance out the rear 255, wider on all 4 was even better.
The flaw in your explanation is that the tire patch is always the same size (area). You can change the relative shape of the patch with a wider tire, but not its size (area)!
You’re explanations of the concepts at work here with brakes and tire grip are just the best. Thank you so much. Love the channel too. Can’t wait for more of your content.
Good explanation, but one point missed. If you are upgrading to larger diameter rotor with appropriate caliper and pad. In this case even the braking force on pad might be the same as before, the brake torque is still higher measured on the hub, because of the larger radius.
It is, but it does not contribute to total braking distance on its own. Stock brakes already have enough friction to reach above maximum grip on your tires. However with a bigger brake rotor with upgraded calipers and pads the brake pedal feeling will be different, because the amount of pressure needed on the brake pedal to achieve above maximum grip on your tires is less as a result of increased brake torque. This means that slaming brakes all the way on a stock car and a car with upgraded brakes will result in same (or almost same) braking distance, but pushing your brake pedal to, lets say, 10% of it's travel will have greater effect on a car with bigger brakes. (assuming everything else in said cars is the same, which is almost never the case)
Brake kits with larger rotors often have more individual pots, so can apply more 'normal' force. This may not actually help much if the standard brakes can lock the wheels at typical driving speeds. However it will help if you've increased the power of the vehicle, or fitted wider tires! An area missed by this analysis is that a custom brake kit may have better mechanical function. What do I mean by that? Better pedal feel, more progressive braking force. These may make the experience of braking a whole lot more predictable and pleasant. This really does seem to be the case with (for e.g) Brembo kits - in some cases the actual braking distance improvement might be really small, but the *experience* means you have confidence to mash them and achieve much better stopping!
Thank you very much for this. After studying Automotive technology in my younger days. My teacher never talked about braking system like this apart from how they worked and different types . This for me is much more informative and educational.
This is a great explanation covering a lot of basics. The other big reason why bigger breaks don't stop a car faster is stock cars are all designed with breaks that can overcome tire-friction's forces and cause wheel lock up with maximum applied pressure. ABS then helps prevent skidding, but it still activates because breaking force can become higher than tire-force in every stock car manufactured. Thus in real-world practice suspension design and tire size are the only real factors influence stopping distance with cold breaks. Which if you are cursing down the highway or driving about town, your breaks are gonna be local air temperature or close to it, thus "cold." And suspension design is NOT to be understated in its role given a good management of weight transfer can maintain more weight on the rear tires, thus increasing total contact pressure over all 4 wheels, leading to a notably higher traction. If weight transfer is extreme because a soft suspension that "dives," while yes the front tires will load with much higher pressure thus much higher traction, the rear tires could lose so much "weight" they fall into the point where rubber rapidly starts to lose friction with reduced normal force. Thus the car's total available traction can dramatically decrease, as much as I think 30-40%. And as mentioned, rubber has a point where any additional load doesn't generate a noticeable increased in friction so the front's very high weight transfer will not compensate for loss of rear wheel traction past a point. Worse yet is if the rear tires unload badly enough, the car can become highly unstable, and subject to "oversteer" (aka spin out) if its not moving PERFECTLY straight while breaking hard. Even the smallest turn of the steering wheel could cause a spin out in this condition This is why manufactures will actually go through a lot of trouble to balance ride smoothness with shock/spring stiffness to prevent even road cars from "diving" under heavy breaking as much as they reasonably can. In fact as consumers become aware that well-tuned suspensions make for much more controllable, thus safer cars, we need a very large increase in tolerance for a slightly firmer ride in exchange for that safety. Which is one of the reason why the old soft suspension street cars that use to scrape their bumpers when breaking have all but vanished from the market.
Not only are they immaculate, but they are also very approximate in a lot of ways. So many variables. Flex, tolerance, etc. Its totally a case where art and science meet.
@@Nbomber It's also, unfortunately, a case where people often try to use the art of things to negate scientific fact eg. exhaust diameter and the idea of backpressure. Some things are absolutely a feel it out and use experience kinda thing, and many things that involve science can only be approximated... but some people take that as license to bin the science entirely and put on their big-boy anti-intellectual pants and very loudly make claims about things they refuse to understand because they've heard too much "common sense".... I'll admit I've got a chip on my block about this specific issue, but I'm basically just adding that you're right that some things have a feel to them and can't be modeled exactly, but some people take that a step further and just insist that you can't "know" anything... which philosophically is fair, but from an engineering standpoint, yeah.. you absolutely can. (Again, not contradicting you, I agree with what you've said.. just adding a little nuance.)
(... but gods, is the internet discussion around exhaust diameter really absurdly heated for a subject that while hard to model exactly... conforms perfectly to a set of thoroughly established rules, give or take a non-negligible margin for real world variability. The discussion on that topic is a frustrating quagmire.)
@@LifeInJambles nah i hear you man, and you are right. Especially when somebody says "and this is my patented special method of doing......". They exist in every feild though. you hit the nail on the head about the philosophical part though. Engineering is in a large part the science of compromise. With everything being "good enough". Tolerances being how tight the margin is for wether something is good enough or not. Theoretically, everything in a car is loose and sloppy, not square, not straight, not flat, not clean, not round, not balanced, etc.
@@LifeInJambles actually, i remember there being some "wisdom" about running subaru engines with loose piston ring gaps, for some reason (i think it was subaru engines). Obviously this is pretty idiotic, but a lot of people took it as gospel.
But extra "stopping torque" beyond what's required to lock up the wheels is irrelevant. The limiting factor in reducing stopping distance is almost always grip.
@@itsasecret2298 Right but without driving every single vehicle ever made how do we know which vehicles need more stopping power and which need more traction? This is an extremely case by case basis.
@@Saddedude There's really nothing case by case about this. Braking systems in every mass produced consumer vehicle are capable of locking up the wheels. If they aren't on any individual vehicle that's a sign of mechanical failure which needs to be repaired.
One of the purposes of a big brake kit is to get the calipers further away from the center of your wheel. You may not increase the force of the pads on the disks, but you are creating a larger torque. Torque is the product of force and distance. Torque is what actually slows your car down
No your upgrading to big brakes (unless it’s a 50s drum brake) to decrease heat. Your stock single piston caliper can lock your wheels, just not for long
@@prdoyle fair point, but as soon as you increase mass you're going to need more torque. Especially in something like a truck hauling material. 1st gen Toyota Tundras, for example, have notoriously under-powered brakes
I used to think it was because for larger disc brakes, the brake calliper would be attached at a point further away from the axis of rotation and hence have lower torque, needing lesser force to stop the wheel rotation than if the brake calliper was nearer to the axis of rotation. Well thanks for the explanation!
Thanks for putting a finer point on our understanding of brake distance vs tire and brake size. I track a car(s) and upgrade the pads FIRST and as I get better and it is a bit amazing to be stopped due to red flag have SMOKE pouring out of my wheels and know I hadn't given up any braking force yet...When I get fast enough to make my brakes cry out in pain I will invest in those big brakes.
What you DIDN'T go into is that all tires have a different compound, and therefore a different µ. A case in point, back when "retreaded" tires were more common, they were barred from certain races, not because they are more prone to self-destruct, but because they were a "softer" rubber, and has more grip for the same size and tread pattern.
Yeah he missed that and also the fact that wider tires don't increase the contact patch proportionally, the patch will get less long longitudinally. Contact patches are two dimensional.
Thank you for the second video, it is appreciated. 😁 Brakes and tires should be matched to one another, or you could get into trouble. For example, bigger diameter tires require bigger brakes ... something off-roaders sometimes forget. Something like a 3 ton Jeep going down the highway on 40" tires and with bottle top caps for brake discs is incredibly dangerous !
If tyres pressure is same, wider tyre will have similar contact surface. If braking pads friction force is the same larger diameter brakes discs will generates greater braking torque.
Hello D4A! Thx a lot for this video. It's amazing how much knowledge you share with us. I study mechanical engineering, and even your most theoretical videos are much practical and entertaining. Salute from Brazil! 🤘🏼
Nobody's mentioned that depending on the car, if you have a lot of negative camber, a wider tire isn't doing anything for braking since some of the outer edge won't be touching the ground anyway.
Yes but bigger brakes wouldn't help either becaus the problem isn't braking force but grip (I am aware that is not what you said, i am just clarifying).
I asked a Dunlop engineer why slick tires has higher grip a few years ago. His answer is similar to your explanation. He said slick tire can grab on to more surface imperfection.
Slicks effectively work because they're softer and people typically go with a wider Tire with slicks but the main reason they work better is because they're softer regular passenger vehicle tires are designed to have a certain amount of rigidity to them especially all season tires as opposed to summer only tires so that they're effective in a wider range of temperatures whereas slicks are designed to be softer and get even softer and stickier upon heating up if you've ever actually use slicks when people do burnouts and then are able to get significantly better times it's because of the traction on their tires has increased now that the tires are effectively sticky and softer
@@rangersmith4652 in a place with controlled climate to otherwise they would only be good during a certain temperature range and also softer tires make for weaker tires part of that rigidity in commercial tires would be for penetration resistance and additional suspension absorption as your tires act as a added layer of suspension on your car where slicks sort of fail at that but yeah you just have to warm them up in the morning with a good old burnout and youd be on your way xD but yea all roads would have to be like highways and they'd need to be swept
@@rangersmith4652 also the rigidity from commercial tires adds to the tire life along with on the other side the softness of the slicks decreases the slick's life
@@altaccount3760 But slicks don't have to use a soft compound. They almost always do because they're not sold as street tires, just racing tires, so ultimate grip is valued over longevity.
a friend from long ago, told how on a very wet motorway/freeway, he was having trouble with traction due to aquaplaning as he had wide as tyres,, and was amazed when a citroen cv2 easily overtook him.. in my experience , narrow tyres on gravel roads, wet or dry, is like driving on tarseal, compared to the wider tyres I swapped from..
correction: surface are IS in the formula *twice*, you just don't see it because the coefficient of friction multiplies by that area, while the downward force divides by that area, thus the area does not show up in the abridged version of that formula.
also your explanation of why thin tires perform better on wet conditions is not entirely correct. water does not care about the distance, it cares about displacement. wider tires have more displacement, that displacement generates buoyancy, which works against the gravitational force acting on said tires, which reduces the normal force, thus decreasing friction.
If the two area values cancel out, then the formula is not "abridged" without them. It rightfully doesn't need them at all. Area never need be considered in the first place.
I discussed this with one of my patrons over on patreon. Yes that's true but not in the sense that it's true on bicyciles whre you have 26, 27, 28 inch wheels and the distance between discs and rim brakes is significant. In cars you are very much limited by the amount of how much you can increase the disc. We're talking about a noticeable amount of surface area but only a few centimeters of diameter. This added leverage is negligible when you put it against the masses and forces present in an average car.
@@d4a Re bicycles - I thought about a 26 inch front wheel with either 6 inch or 8 inch disk rotor. It makes a huge difference because of the higher leverage you don't need less braking pressure on the pads. But totally agree - just from friction point of view, higher surface area on brake pads do not help (unless you consider the heat dissipation). As always - great stuff !
a larger radius rotor also typically has more mass to it than a smaller rotor, and therefore requires more force to stop it as well. larger mass, longer stopping distance... going big isnt necessarily of benefit.
Biger disks and pads also contribute alot to breaking faster and more efficient. bigger disks mean bigger pads, which translates to more surface area and bigger breaking momentum/torque (because of the size). Also bigger contact area dissipates the friction heat more evenly, which means breaks dont heat up so much and the ware of the pads is smaller :)
Been in the car business / racing and never even really thought about this. Just assumed bigger better. Thank you so much for your video of and the way you explained it is beautifully understandable, appreciate it! New subscriber going forward can't wait to watch more.
i am not here to disagree, because all of these make sense and of course play a role. But the larger in diameter the brake disc is and the bigger the brake pad size, will have much more friction area and that way, we can apply more force than previously and get better results. this video only talks about applying the same force. rather than in reality, installing a larger rotor, and bigger caliper, often means the master cylinder will be also larger so you can apply more pressure onto the surface area. and that is without taking into consideration fixed calipers versus floating calipers and the advantages on them.
"we can apply more force than previously and get better results." No. For one very simple reason: It does not matter how much torque you theoretically could apply for braking if the tires start slipping.
A bigger disk diameter for more powerful braking is not really about more surface contact, but the pad contact being further from the center of the hub, so it is a longer lever, and does greatly increase stopping power,---if the tires hold the road surface. The flip side is heat. More surface speed is had by the bigger disk, (more distance around the circle for the same rpm.), so it will generate more heat. All coefficients of friction being the same, the amount of heat developed, (before dissipation), shows the braking power nicely. But the friction of the tire on the ground has to be more than the braking so the tire does not lock up. So wider tires are used for applications of aggressive braking, (racing). From different road surface condition, (from ice to dry clean pavement), different tires and different braking systems, to say the tires are the difference and not the brakes for distance is a bad statement. I am sure many car tests were dine with similar car weight, the same tires, and different performing brakes, (the only factor of difference), and if all the tires don't skid 100% of the time when braking, you will have different stopping distances.
I think the argument is that if you can already lock up your wheels (i.e. ABS engages) then you're getting all the braking the car is capable of without upgrading tyres, suspension etc. But yes, bigger brakes do give a bigger lever arm so the calipers don't need to squeeze as tightly for the same amount of deceleration. Doesn't lower stopping distance appreciably though.
He never stated that braking force isn’t actually bigger in real life scenario, but it doesn’t matter as standard brakes can lockup tires, so you’re not limited by braking force, but by tire grip. Of course it’s different when you race, then you put beefier slicks and just maybe then you’d be limited by brake force, but I still doubt it. Certainly limited by brake fade, but that’s not the point.
@@driv3ver yeah and no, if you ride motorbikes you’ll quickly see an extra 40mm on the front rotor makes a massive difference, I know he’s talking cars but he rides aswell.
@@merkel2750 That’s only if OEM system is lacking. I’ve been riding years ago too. What you’ll always notice with bigger discs is that you need lees pedal or lever travel for the same stopping strength, but still threshold is the same at tire’s grip level. Which leads to less precise braking, because very little force applied on pedal or lever will initiate high brake force and doesn’t let you modulate that well. You’ll be locking up with let’s say 50% travel instead of 90%, so you won’t be that precise. In the end bigger disc will make you feel like your brakes are better, but if you compare stopping distance it will be the same or worse (brake bias!). I’m occasionally driving on track days, and if OEM system is good, then even for track racing it’s enough to only maintain it well, put good brake fluid, steel braided lines, good rotors and racing pads. Unless you’re getting much more HP than stock then BBK may be the way to go due to heat issues.
Also for most people Handbrake shoes are a lifetime part or only need replacing when they have cracks or rot. as they should never wear out really as the car should never be moving while its being engaged so it cant wear. Many brake places will scam customers saying they need new handbrake pads and never put new ones on as those with 500,000km on them still at 95% thickness.
Some thing you didnt metion is that Brakes are basically never the limiting factor. Even Stock Discs and pads can apply enough braking force to overcome the friction of the tires. As the normal force of the brakes is a changing variable by just pressing harder on the brake. the limiting factor on there is just how hard you can press the pedal (and how much its amplified) theoretically all the way to mechanical failure. That is why ABS or anti lock braking sytems exist. Once the brakes overcome the force the tires can actually apply to the ground, ABS limits your braking force to stop the tires from locking up. 2 reasons why tires shouldnt lock up: 1. you still have have control (locked up wheels cant steer) 2. static friction is alway higher than sliding friction
This is a very interesting discussion of the F=MU x N, sorry I couldn’t use the proper symbol for coefficient of friction. May I add that, while it is understandable that bigger brakes will not stop a modern ABS equipped car faster, bigger (greater coefficient of friction) brakes will stop an older car, especially one originally equipped with organic shoes and drums all around, faster and this is reduction in stopping distance is of course enhanced with greater tire contact area. Anyway, getting back to the discussion of the F=MU x N equation and how it does not apply to tires (at least not in a linear fashion), I thought it might be interesting to discuss the topic of how weight transfer, biased toward a particular end of a chassis, might manifest itself in the cornering behavior of that chassis. Thank you for taking the time to present such an interesting TH-cam channel, your efforts are appreciated.
We had a Car content youtuber that work as a tuner and worked on VW designing brakes, and he had a tough time explaining the same thing, bigger brakes don't make you stop faster. At first he tried to explain using physics but people were not satisfied so he had to literally put into test by recording braking times with original brakes and bigger brakes, the times were the same. And then he made another video, but upgrading only the tires, the results were a lot better. And till this day there are people that do not believe him, even after watching his videos, crazy
The equation is actually Torque = 2•μ•Force•Radius, where the radius is the average radius of the pad. Increasing the radius allows for a greater torque capacity, of which a negative torque is what slows the vehicle.
There was a dirt bike (motorcycle) called the "ATK" developed by Horst Lietiner. He mounted a smaller diameter rear brake dist on the counter-shaft sprocket shaft (front sprocket). The small dis would spin faster than a disk on the rear wheel, but he calculated the surface speed to be the same, (so the heat would be the same). It heated up faster and tended to discolor, (something not seen on the wheels of a dirt bike disk). There was not as much surface area and material to dissipate the heat as well. Today, my modern dirt bike has a bigger disk yet,---and it is way too powerful for me,---until the tire slips. You do a good vid.
I was on the highway a few months ago on the way to the beach, it was raining and traffic was backing up, all of a sudden traffic came to a complete stop, I Had to use a lot of brake to stop quickly, I have upgraded wheels and tires, they are lighter and wider, I have the Michelin pilot sport all seasons and I remember how effectively they worked, the car behind me had to swerve into the other land to avoid hitting me from behind, I’ve upgraded my rotors and pads also but i credit the tires for helping me stop so quickly.
You never first saw my comment here all you said here was entirely right, thus it really takes the initiative over non and reality, I could agree with this also as your second video, Rim brakes can be increased their friction due that they can lock more, I hate to do it but I need to do it in order to prevent me from accident.
Big brakes do two things. Look good, and provide increased potential heat dissipation, which helps reduce brake fade during repeated hard braking (like on track day.) That's it.
11:50 this is not a rubber ball! Mostly air is compressed, but I know that it doesn't change the nature of the argument. But other than that, the video is absolutely fantastic. I am a physicist and it never ceases to amaze me how much different the apparent same world of engineering is from physics. Very informative, many thanks!
The best explanation of this subject that I have come across! There's so much science and physics involved with this, yet you did a commendable job of explaining it to us common folk in terms we can understand.🤩 Thank you.
With 35x12.5 R15 tyres on my ancient vehicle, it stops incredibly good, even when the brakes are somewhat old. I could not believe the difference between the stopping capabilities between the vehicle with P215/75 R15 tyres. The offroad abilities of the 35x12.5 R15 tyres are also amazing. The only sacrifice I have is slightly slower take-off, and a tiny bit less fuel economy that was rectified when I regeared the differentials. I can never go back to driving a worthless, urban, manicured road, street car, especially where I live.
Follow-up video that covers larger disc leverage and other questions this video may raise: th-cam.com/video/Ql9eYh31kTw/w-d-xo.html
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3:14 what a quote!
7:08 that's not entirely true. motorcycle brakes need to dissipate a lot less power because of the lower overall weight. for this reason they are skinnier then care ones
I hope you're okay in Serbia. I know things are getting crazy over there ... and we all love you.
Honestly, they're also going to get crazy here in the US, too ... The US is making a mess of the world.
And many of us feel badly for what idiots our leaders have been. Blowing up NS 1 and half of 2?? (SMH)
Another reason why adding bigger brakes to your car won't necessarily improve braking performance, is if you cannot add wider tires to it - If the original brakes can already outperform the tires, you will need tires to improve braking performance, no matter what brake disc/pad you add to the system.
And since a stock car has brakes designed specifically for the tires they ship the car with, the brakes are usually already strong enough to handle the tires, or even overpower them.
in other words bigger is better ... just wait 7 mins to tell everyone about the OBVIOUS brake fade... sure, whatever.
It was over 30 years ago that my physics professor used the formula for friction to tell me I was wrong in believing that wider tires provide more grip. I knew I was right but I couldn’t prove it to him. I very much appreciate the answer, even if it’s 30 years late. Ha. Thank you!
On a straight of a smooth surface probably doesn’t get you more grip, but wider tires mean more surface meaning higher limit when it comes to wear and heat, and irl grip isn’t just about stickiness it’s also about more space for the rubber to be stuck between rocks so it can literally push itself forward rather than using friction
@@Maaaaaax-07 there’s static friction where the forces are low enough to not lose it, there’s also kinetic friction where you slide
I distinctly remember an old physics text book saying that wider or more tires don’t improve braking. I’m thinking “so why don’t race cars use bicycle tires to save weight?” This video was excellent.
High school physics doesn't take in consideration that friction can go above 1.
@@jeremykoehnlein2158 ok it doesn’t improve braking BUT ya slow down faster bc of drag speed is effected also but… with much weight smaller tires grip harder per square inch there is a perfect width for every speed size weight combo… the drivers style can also be a difference also larger tires add more weight wich does help friction more so… yeah but. Anyways… just another way of saying….
I'm a tire design engineer who worked on some of the slicks you showed, wanted to say, great explanation!
If you are a design engineer you would know that this guy made a non point.
I’ve never heard anybody claiming that “big brakes” make the initial cold stop shorter.
On the contrary pretty much everyone with a sporty car knows that big brakes are for making repeated stops shorter, which they absolutely do.
Also, even if he added an asterisk and said “big brakes don’t make your first stop shorter” well, he’d still be wrong. go ahead and mount bicycle brakes to your suv and tell me again about how brake size doesn’t matter. They should start running miata brakes on tractor trailer trucks now?
@@WithCarePlz The question is that most of the brakes that are used in cars are more than sufficient for the type of tire they use, it's not surprising that the ABS system exists, precisely to control braking, because if the brake works at its maximum limit it will most likely lock the wheel, which ends up making your braking distance worse. Finally, you ended up giving a very bad example, because obviously he is mentioning that the size of the brake does not matter, because he considers the stock car brakes, which have more than necessary performance to achieve the needed braking (it's even stupid saying bicycle brakes on an suv would not work, as obviously suv's don't come with bicycle brakes).
@@gamerbg294 thk you for the response to ozzy its ok to think outside the box but i think he went out to the pasture on that one. comparing apples to bananas 😁
As an expert (not trolling you) please read my comment above concerning the shape of the contact patch and tell me if you think it is correct. Oh never mind, I'll just cut and paste it here:
Excellent presentation, as far as he went....see, one must also take into account the shape of the contact patch of the tire on the road. Skinny tires have an elongated (front to back) patch while wide tires have the opposite, which is a wider contact patch. This is critical on motorcycles especially. A thin contact patch will, because the tire is elastic, under hard/extreme friction will cause the tire to "ripple" making the bottom of the tire the shape of a sine wave. Reducing contact with the road while a wide tire with it's wider contact patch will deform much less, giving better "stiction". And worthy of note, no matter what size/shape of tire, the contact patch area remains the same. The shape will be different but the surface area contacting the ground will be the same. I wish he'd have added this information to the video as it is not a minor consideration but a major factor in handling and braking and acceleration. I give the video a thumbs up because everything he said was spot on correct, just incomplete so in school grade terms, an A minus.
Please tell me if I am correct.
@@fireballxl-5748 I tend to agree with some of what you’re saying about contact patches. We disagree on his video. I feel that he is being very disingenuous. Bigger brakes are to prevent fading. Bigger brakes are for repeated stops as in performance driving which is why nearly every performance car sold has bigger brakes than the lower trim models. I feel like the internet just likes to whore themselves and clickbait things like this with catchy or juxtaposed nonsense such as “bigger brakes don’t stop better”
Yeah. They do.
Let me know when Ferraris stop coming with 16” carbon ceramic brakes and start coming with little huffy bicycle brakes instead since this guy and the internet say that “bigger brakes don’t help you stop better”
I always considered it this way: If your brakes can lock up, you already have more stopping power than you need. If you really want to stop, you need more rubber on the road. This is why ABS is a thing. Practically all modern car brakes are too strong for their purpose. As such, the means to improve them is to artificially weaken them so they don't defeat the tires capability.
That would mean all the engineers are dimwits. Why not make smaller brakes?
@@tedmoss smaller brakes means smaller surface area means dissipate less heat, i mean what the fuck dude do you even watch the video before replaying to this dude?
@@tedmoss Because only a dimwit would put weak parts on a system designed to avoid killing people.
Most times you apply brakes more then once and then the stock brakes fade and fail under high load HEAT
I had a 1946 willys jeep. First year for civilian sales.
You could stand on the brake pedal and still have to throw out an anchor to get it to stop quickly. 7" drums with a 302 ci Ford V8 didn't help an already bad situation. It go across a rice field. But wouldn't climb up the grass covered river levy. It would stop half the way up and slide backwards to the bottom.
35x12" wide tires are great. Just not for traction. Spelling edits. God I better start wearing my glasses.
Bigger brakes will usually have larger pistons and possibly a higher number of pistons, so the same hydraulic pressure applied to the brakes will actually result in a higher force pressing the pads to the rotors. But this of course means very little, when the tires themselves are unable to withstand the increased braking power.
Upgrading both is the way to go. :)
Also increasing the diameter of the brake discs, we also increase the torque resistance arm
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It's not the amount of pistons but the area they press with matters (not the area pad at all, cannot be mistaken). Bigger amount of pistons usualy means they're smaller diameter pistons. Until You calculate the whole pistons' area, You cannot say 'more pistons result with a higher presssing force' as it's not precise.
Plus - bigger rotors (bigger diameter) means higher torque applied with same force used, hence it's easier to stop a car. I don't know why it's not mentioned in this film, as it's very obvious.
The fact that 20 people like your very vague point that's not even an explanation proves we have very little hope for humanity.
bigger brake rotors and pads only spreads the braking friction out over a bigger area. Reducing heat accumulation and wear across the total area. You simply get longevity in extreme circumstances.
I have a small car workshop in Thailand. I explained a lot to my customers, as you said.
If they use the car in normal conditions, e.g., in everyday life.
It's optional to upgrade the brake if they want, but just OEM. It's entirely enough.
Investing more money in new tires is a better option. It's the fence between the car and the street.
For example, most cars didn't upgrade their brakes and could drive on the German autobahn safely without a speed limit.
That means the OEM specification it's enough.
You're very professional from the practical to the theoretical view.
With suitable examples, good explanations, and easy listening. That's super cool!
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As an Engineer, I love how you explain things with formula and science but simplifies the theories so people without the technical knowledge can understand. Also as I car guy, I love how things I learned in University have application to my hobby. Win, win in my books.
Consider he never mentions how bigger discs give better leverage over the rotation of the wheel/axle. Am Also an engineer.
@@eggmcnog You are right. IMO, he skims across so many details w/o considering many important details. Pounds per square inch, foot pounds, etc.
@@1dave301 he’s right about all the friction stuff without being too dense but ignores the leverage aspect altogether
Well then this is not the video to learn from. The whole point of bigger brakes is that they don't lock up and have less friction. Which contradicts the point he's trying to make. Bigger brakes are effective by not locking up as easily. Because when they lock-up (from too much friction) your braking is only as good as the sliding rubber (tire) on the concrete.
At the end of the day force of pushing the brake pads on the disk is roughly the same. But smaller brakes have less surface area resulting in more friction we don't want as it leads to locking up your brakes.
It's still a useful video from physics standpoint, but certainly not from automotive.
PS. Cars have ABS yes, but your braking will still be far less effective if it has to kick in more than it would have otherwise.
I am an engineer
Totally agree with what you say. Where the bigger breaks bring benefits is that they have a higher thermal mass to absorb and then dissipate the large and repetitive energy of breaking. I fit upgraded two piece breaks, pads, and very high temp fluid in the STI. The result was less fade and shorter stopping distances. A side benefit was lighter disk assemblies as well as forged rims for a loss of near 9Kg per corner. Larger and better gripping tires tend to bring with them the requirement of up graded breaking components.
Bones break. Cars brake.
as someone working in a dealership, i see this quite often.
people want good brakes, such as ate, brembo, but if you ask them about tires they often pick the cheap options because the actually goods ones are too "expensive".
so you want good brakes while also dont?
We just want everything without spending our precious money. Surely you can make that happen?
Bigger brakes can hold more heat before overheating and they dissipate heat faster. Putting tiny brakes on a race car may lock up the tires, but they will overheat instantly.
Also a larger rotor will give the calliper more leverage to stop the wheel.
Anyway I think that unless your brakes are tiny, or you do hard tracking with a powerful car, a simple pad upgrade is all you need.
Great video. But don’t larger diameter rotors place the caliper slightly farther from the center of the wheel which allows the caliper to have a greater moment arm which puts more torque on the wheel than does a caliper on a smaller diameter rotor? If smaller diameter rotors performed just as well as larger diameter rotors, sports cars would use smaller rotors to save weight.
You might also want to do a video on multi piston calipers and two piece rotors. My 2003 RS6 has 8 piston front calipers and huge, two piece rotors and stops in less distance than any other car I have ever owned.
@@glenwoodriverresidentsgrou136 If your small brakes can lock up the tires, the only thing bigger brakes will give you is better resistance to heat fading. More metal = more thermal mass therefore, harder to overheat.
However you’re right, if you have really sticky and wide tires you need big brakes to use them to their full potential. Race cars have a ton of grip and therefore require big brakes to max out the braking grip.
Tire grip determines stopping distance, and your brakes only need to be able lock them up to get the most benefit (which many “small” brakes can do even to tires like PS4S etc.). So at that point, bigger brakes only helps reduce heat fade by increasing mass and cooling area.
My gti has relatively small brakes but it can lock up warmed up 245 Pilot sport 4s pretty easily. This means that my one-time stopping distance wouldn’t decrease with larger brakes, but it would be more consistent around a track with multiple braking zones. If I fit some really sticky tires the brakes probably wouldn’t be able to lock them up anymore at which point I’d indeed need bigger brakes.
Your 100% write. But people that don't know this won't understand.
It isn't that you expect a big brake kit to stop you faster. I know better than that. If your brakes are strong enough to lock up your tires, then you're not going to gain anything with a bigger brake kit. What you will gain in most cases is reduced fade. Both by additional Mass for the Heat to go into, and greater heat dissipation assuming that the disc is reasonably designed. In some cases, these aftermarket discs will perform less well initially. Because they're designed to be used at the edge of performance and really give their best performance once they are hot and the braking compound has chosen to work with that.
When the brakes are still cold, you may have a stiff or slick feel to it like it's not braking very well at all.
I have a 2021 Mazda3 turbo which I bought at the very end of 2021. 2282 I put 54000 miles on the car, I drive a lot. And it is through the North Georgia Mountains so it's a lot of curvy roads with long steep grades.
Do not get me wrong. I love my little car. For daily driver it is awesome. The tiniest little GT car ever. It will effortlessly hold 90 miles an hour while getting 28 miles to the gallon, it has plenty of power for passing and can squirt up and down those mountains.
But. And it's a big but. The front brakes are inadequate for truly spirited driving. In less than 3 Mi coming down Brasstown Bald oh, I was able to get the brakes so hot that breaking Effectiveness was reduced by 80 to 90%. Toward the end I was actually a bit concerned, having to use engine braking and sudden darting movements to get the car to slide a bit to scrub speed.
In Daily driving, I've never had a problem with it. But I have chosen to get the corksport big brake kit oh, and the next time I'm due to buy tires, I'll be swapping out the tires, wheels & installing the brake kit.
For now, I've chosen a high-temperature compound for my brake pads. It does mean braking is a little bit subpar when the discs are cold. But far from dangerous. And as the discs get hot, fade is greatly reduced.
I don't know why voice typing randomly inserts "oh"
I've recorded myself talking, and I don't say that or anything that sounds like it.
Once again, you've thoroughly explained the subject with magnificent clarity. I'm constantly blown away by the quality of your videos.
I think that the reason is much simpler. Most brakes are already able to lock up the wheels while braking so pressure increase won't help, because the wheel can be already locked up with smaller brakes (that is also why every new car has ABS).
This means that breaking performance for most cars isn't brake pressure limited, bud tire grip limited.
Larger tires will have more grip and more grip means more friction, which improves braking performance.
Some cars have OEM brakes that are just enough to reach the ABS threshold on the OEM tires. I have a car that was unable to reach the ABS threshold on smooth, clean, dry pavement after I put on stickier rubber. My solution was pads with a higher coefficient of friction than the OEM pads, and it solved the problem very well. I suppose larger diameter disks would have solved the problem too, but I didn't want the extra unsprung and rotating mass. Replacing the pads was an easier, less expensive fix also.
@@xtnuser5338 Yup similar here, I think tire technology has improved enough over the past 15 years that the OEM brakes on my car no longer are able to reach the ABS threshold on smooth dry tarmac. Given that I also want to fit slightly wider tires because the OEM fit is really slightly too small for the rim for some reason, I'll definitely be upgrading the brakes too when I can.
TRUE, Until the second hard application and the small factory brakes are fading from overheating .. there's far more to brakes than presented in this video
which could require larger brakes. at some point the grip is so much that u need larger brakes to lock it up with abs.
@@jkoorts At some point, the grip is so much that you need more stopping torque to lock it up with abs. That could be accomplished with larger diameter rotors, or it could be accomplished with better brake pads alone. That's how I solved the problem.
I installed much stickier tires, and could no longer trigger ABS on smooth, dry pavement. I understand the physics, and knew that I could use more stopping torque, but also knew that I did NOT need more heat management capacity. So I selected pads with a proportionately higher coefficient of friction to try matching them to the increased tire grip. This solution worked perfectly, while being way less trouble and way less cost than installing a big brake kit.
i thought bigger brakes were more to aid in cooling by having more surface area and longer times to heat up through greater mass...
It does.
That's short of right. Bigger brake rotors and bigger (more pistons) calipers to go along with wider tires will get you better/shorter braking distances. Just because you get wider tires doesn't necessarily mean you'll stop faster, because if your smaller brakes don't have the stopping power to go along the the extra grip from wider tires, your still losing out of stopping distance, plus the smaller brakes heat up faster causing brake fade which could ruin your day and your car.
That is correct, the thing is bigger brakes are more efficient in dissipating heat making braking more consistent and predictable. Altho without the grip from better tires u will only end up locking up ur tires which can be dangerous in emergency braking situations...it is why brakes and tires are ideally upgraded at the same time
@@bluegizmo1983 exactly. It all depends on what the weakest link is. Bigger brakes show the tires weaknesses more.
But the biggest benefits are heat dissipation and consistency, and lets not ignore the obvious elephant in the room....
They look cool.
Kaiden you have intuited what most who oay attention refer to as thermal mass 😃
I feel like you could do a more advanced video on brakes too. Such as larger brakes having a centre of braking pressure further from the wheel hub so you can brake harder with less force. Or even talking about how pads warp and why multi piston brakes have an advantage etc etc. love the vids ❤
Larger brakes are not about stopping power, but rather better cooling under high loads.
@@wmgilliland2582 yeah I know, but higher brake pressure starts to warp pads and heat them unevenly which causes the brake fade to come on sooner. Nothings absolutely rigid so the larger brakes are more than simply better cooling.
@@abbottboyaustin I'm with you Austin. An obvious example is all the superbikes with the huge diameter rotors and a small pad contact area.. The length of the 'lever' has a huge effect etc...
@@abbottboyaustin , is that not what I just said? It's about cooling capacity to help keep that from happening.
For sure. The initial explanation in the video is wrong.
Bigger rotors = more leverage = more brake power
More piston area on the caliper = more force = more friction = more brake power
The stopping distance do not change cause the stock brakes already have more than enough power to lock the wheels, so using a good ABS system you are already performing the minimal brake distance on regular cars.
Great video. I actually asked a friend of mine when I learned about this formula almost 10 years ago. He's an automotive engineer, but he couldn't really explain it and shrugged saying it's experimental evidence that did not align with the mathematical formula. I of course already figured it out by now, but I would have loved your explanation back then!
I always wondered why tire width matters but the formula says otherwise. After watching your "Why are Front Brakes Larger than Rear Ones? Brake Bias Explained" I was really wondering. Thank you for explaining all the complexities and how it applies in reality reguarding tire width. It is hard to find good information like this. Your explanations are excellent! Thank you.
Before vid, my understanding of big brakes was they allow better cooling to allow better braking over time. Larger area allows more heat transfer which means when you have to consistently hard brake (track driving) you are less likely to overheat and experience brake fade
This is true, and this is also why cross drilled rotors are a detriment to braking performance on the track. You are literally removing mass from your brake rotors for no advantage what-so-ever.
Ideally, you want to find the sweet spot between mass and heat absorption. Drilled rotors add no benefit in this area over a set of slightly smaller solid rotors, but they do cause problems with stress fracturing, and premature pad wear.
If you go to a club race, pay attention to the kinds of rotors all the top guys a running. I guarantee they will be solid rotors.
(The above is not meant to apply to carbon rotors.)
@@operator0 " Larger area allows more heat transfer" this is not the main reason to increase pads size. You can increase heat transfer without increasing pads size - better ventilation, increasing disks size without increasing break pads size etc. Main reason - bigger pads wear slower, as there is more material to wear.
@@bumbarabun Not necessarily. If the pads are wearing at the same rate, they will wear out just as quickly.
@@severnsea if you have bigger pads (contact area) they will wear slower than smaller ones.
@@bumbarabun I repeat, not necessarily. If the pads are wearing at the same rate, they will wear out just as quickly.
Look, imagine the surface area of your pads was the tip of a marker pen. If you draw with that marker pen it will run out eventually. If you double the contact area by taping 2 marker pens together, they will still run out at the same time. You have double the contact area but you're still using it at the same rate. Try it! It won't be exactly the same, there are other factors involved that can make a difference, but that's why bigger pads won't necessarily stop you any sooner.
Don't forget bigger breaks offer better leverage to stop the wheel :) it's simple though as somebody who grew up loving every single racing sim. if you can lockup your wheels then you need better / wider tires. If you can't, you need better brakes. that's all you really need to know from a maximizing performance standpoint. rinse and repeat until you have the breaking performance you desire.
Winner 🤟
Brakes will outbrake breaks anyday!!!
I just upgraded my brakes from tiny single piston callipers and small rotors to larger twin piston callipers and much larger rotors! the smaller brakes struggled to stop with consistency and I found it easy to have less than desired stopping abilities and harder applications of the brakes would result in lockup’s now with much more braking capability the consistency is much better and although over braking can result in a locking wheel it’s much easier to have complete control and feel the limit of traction with brakes that aren’t at the limit of thermal absorbing
Really depends on what you're locking. And that comes down to mechanical grip. Weight transfer left to right and rear to front all play a part in overloading the tire.
Exactly, larger rotors rarely have significantly larger pads… they have a larger diameter, resulting in better leverage, needing less force on the pads to equal the stopping power… which reduces friction and heat as well.
Wow!!! The way that you differentiate between friction of various materials--and wet vs dry--was fantastic! And your illustrations were excellently suited to the topic at hand while keeping things interesting and fun to watch! Well done, Sir! I'm looking forward to learning more about tires in the future--high vs low profile, soft vs hard compound, wide vs narrow, summer vs winter, etc. Keep up the great work!
Don't get carried away, he isn't that good.
I read an article on this topic years ago and having this mental model of how tires create grip has provided so much benefit. Once you understand the concept you can derive all sorts of other things, some of which you talked about. For example, knowing that a tire's grip doesn't scale linearly with the amount of force with which it is pressed into the road you can see why things like low profile tires can help keep more of the rubber in contact with the road due to reduced deformation under load. It also helps explain how things like camber, roll stiffness and tire pressure all contribute to maximizing the grip in a given situation (when a car is cornering the grip lost on the inside is greater than the grip gained on the outside so all of the painstaking setup work on a racecar is ultimately about trying to create the least deviation in tire load across all points of contact since the best possible grip is when all parts of all tires are as evenly loaded as possible.)
And there's also different friction coefficient for sliding and rolling contact... rolling rubber on road is 1, sliding rubber on road is .5.... rolling rubber on wet road is .5, sliding was .25... that one stuck with me.
@@ChrisMah You also have to figure in the tire compound itself... 'sticky' race compounds you can dig a fingernail into will damn near work on a vertical surface, where as your harder compounds won't stick so well, but the tire will last 50,000 miles and probably get great gas mileage too... where the race tire will burn out in 1000 or 1500 miles, and really suck for mileage going down the road.
Like many things, it's a compromise as to which properties your desire and which ones do not matter for your application.
@@kleetus92 Yes, good point. I’m even amazed how sticky some of these 200 tread wear “street” tires can be these days even although still nothing like soft race rubber.
Wow!!! Absolutely fantastic vid!!!! I have experienced brake failure on 2 of my fat tire electric bikes. I have two bike brands that have failed on steep hills: 1) The RadRover 5 and 2) the Juiced Rip Current S. Both bikes have 4" fat tires and have under designed brakes systems to handle the heat issues of braking on steep hills. This is a big safety issue for these and other Ebike brands. Also both bikes take a lot of maintenance, because their brakes are under designed. I only get about 1,000 miles on a set of brake pads on these bikes. Compare this with my Lexus CT200H brakes after 115,000 miles: Zero brake maintenance and the brakes pads are only 50% worn. I really enjoy your real life engineering vids. Thanks, an aircraft tool designer from Seattle.
Absolutely correct that increased surface area for brakes does not mean more friction, but mean effective radius of the braking surface will affect the leverage the brakes have and affect stopping power. So a larger diameter rotor will generally have a larger mean effective radius and more stopping power.
Since most vehicles brakes can overcome the grip of the tires anyway, though, the most notable benefit of larger brakes is the heat dissipation.
Ignoring mean effective radius of the brake rotor when calculating stopping power is incorrect though.
Bigger surface area on pads usually means bigger rotors.
This means more moment on the axle so whilst the friction force may stay the same, you get more stopping power (or less heat) for the same force applied to the pads.
Edit: Not less heat (generated). Typing without thinking.
@Andrew Crews it's more about heat dissipation.
@Andrew Crews Exact, the heat you generate will be the same but there is more thermal mass, there is also more surface area to dissipate heat to the air
use big brake kits if you start feeling squishy brakes
if you just wanna increase braking distance, upgrade to better master cylinder and better stickier brake pad compounds
This should have been covered in the video, but braking force is generally not limited by the amount of pressure you can put on the pad. With brake boosters you can have any force you want pretty much. The main reason you don't get better braking performance with bigger brakes is because you are tire limited anyway. Even normal cars with pitiful brakes have more than enough clamping force to overcome the friction of the tires (hence why ABS exists). So again, the only reason to get bigger brakes is heat management as stated in the video.
Only tire limits amount od momentum, even puny stock brakes can block the wheel, tire is always a bottleneck of this system
@@RENO_K Few people in this comment thread understood the video. If your brakes produce enough pressure to lock up / engage ABS, the ONLY way you can decrease braking distance is if you decrease vehicle weight or get wider / stickier tires. Bigger rotors, better brake pads, etc will never decrease braking distance.
Really well explained ! Glad you added one of the downsides to fitting wider tyres - aquaplaning, a very nasty possibility in heavy rain and it's a given that you'll burn more fuel - real life is full of compromises !!
As usual, extremely high standard of research, explanation and video production. Very professional channel.
Not really.
@@tedmoss "Not really"
Refuses to elaborate.
What did he mean by this?
For motorcycles, putting holes in brake disks improves wet-weather initial (first couple of revolutions once brakes are applied) performance. Slots do the same, maybe better. It also reduces unsprung weight, but probably not enough to matter. Bikes have comparatively little 'sprung' weight, so the sprung / unsprung ratio matters more than it does for cars. One of the best handling mods I ever did for my Ducatis was to swap stock wheels for exactly-the-same-size Marchesini magnesium ones. Same tire models and sizes, big difference in handling. I used to set up bike suspensions for the track, and this was a bigger difference than changing spring rates, preload, or damping.
The drilled holes are functionally allowing more airflow and hence cooling.
The purpose of the slot it to have an edge wipe the pad removing debris and ever so slightly shaving the pad for contact area while chasing the gasses away. That is why it has to go in the proper direction.
Amazing comprehensive explanation of why in wet conditions a narrower tire may perform better.
I've had this argument with several people in the past.
Fact is, stock brakes (at least since the 1990s) are limited by the traction of your tyres. They will apply the naximum amount of braking that physics will allow at least 5 times in a row from a very high speed. Therefore, your street car doesn't need upgraded brakes unless you intend on braking the law. Regardless of how much power it has.
If you're going to the track, then upgraded brakes can help. Generally you'll get by with just track pads.
Which law are you referring to?
@@robair67 the law of "I've driven lots of cars on race tracks with stock brakes all the way up to retired V8 Supercars and know what I'm talking about"
@@1one3_Racing I'm happy to break that law.
@@robair67 I'm not saying you SHOULDN'T upgrade your brakes. My point is, people go from stock brakes with regular pads and think they need to change calipers on road cars. Then when they do and they feel better they think they have improved the brakes. But its just the pad. You can get the same pedal feel and performance from stock calipers by upgrading to a track pad.
Changing calipers means you also need to balance your master cylinder size and fluid capacity and people don't take this account and ruin their brake bias and therefore vehicle safety.
If you're going to change braking components, it needs to be a full system. Otherwise, just use a slotted rotor to keep the gasses off the pad, and run a high temp fluid and pad and you'll get exceptional performance and great pedal feel. Generally going from a large single piston to smaller multi piston setup doesn't actually give you any more surface area anyway. It just distributes the pressure more evenly across the pad and is more for temperature and pad wear than actual braking force.
@@1one3_Racing some years ago I went through a 10 year long phase of driving only front wheel drive cars, when on the road. It was no fun...except for left foot braking! However, it really eats through front pads (and discs) and at one stage my standard compound pads had worn about 3 to 4mm diagonals on the floating calipers. The sliders and pistons were still serviceable and within tolerances! A change to 1144 pads meant better front braking and therefore an increase in line pressure was needed at the rear (drum brakes- 1.6 205) which was achieved by deleting the load valve. The balance was absolutely amazing, even at motorway speeds. This car ended up exclusively a circuit car and the brakes just couldn't keep up. So your explanation definitely bears out my experience with that car. And finally, I may have broken a few statutes and acts of the ministry of transport (!) but I am bound by Common Law, not corporation law!
One Thing you didn't mention is that MU can go above 1 on tire and brake pads. When a track surface is coated with rubber, it's more in the realm of adhesion and suction than friction only. Same with brake pads, your surface area falls on it's face as they require break in which is not only cleaning up the surface, but also adding material to the disc that creates and adhesion layer more than a friction layer. That is why it's important to run brakes in their temperature range where they actually transfer their material to the mating disc.
Excellent video, one point you did not mention is that the rubber mixture can be changed as well, so you can make a wider tire out of softer rubber which will increase its adhesive properties while lasting a similar comparable distance than the stiffer narrower tire.... so many parameters to play with :-)
I think this was a great explanation of the subject. Especially for understanding the underlying concepts. But I would have added the equation of breaking moment which is dependent on the friction force and the moment arm, which in this case is the radius of the applied normal force on the brake pad. Just to show that the friction force and brake diameter are indeed coupled, even though the heat transfer is the actual thing to solve with brake systems.
In the interests of completeness larger diameter discs do give greater breaking force everything else being equal. The reason being the braking force is at a greater average radius from the wheel axis hence increasing the braking torque. This only means less hydraulic pressure is needed. However in practice the hydraulic pressure is not the limiting factor to rate of vehicle deceleration hence none of this changes the premise of this video. Another great video thanks...
This is my favorite educational channel! The way you can explain mechanics in such a clear precise manor is amazing!!
All in all, a good explanation, there are nuances that can turn this in to a multi hour lecture. My practical experience is that I use stock brake rotors and calibers with aggressive pads for racing. Even up to 25 hour endurance races. In a light car (Miata) with the biggest and good tires (Hoosiers R7) that fit within the fenders, I still have more brakes than tires and have never had issues with brake fade. But they do not look as cool as a big brake kit! Keep the videos coming.
interesting. I also race a Mazda (a mazdaspeed 3), and I've upgraded my rotors and pads and tires. I've noticed significant reductions in brake fade since making the change. And I'm only doing hpdes.
@@3MZFE Not sure about the details of your MazdaSpeed3 but looks up the weight and the internet reports around 3,200 LBS without driver. If you drive your HPDE car on the street, then would assume you are using less aggressive pads. My first gen Miata is under 2,200 LBS with driver across the scales at an end of a race (per the rules for the class I race in). I would guess the extra 1,000 + LBS makes a difference. I don't even have to use expensive brake fluid as long as I keep the cheep store brand DOT3 fluid fresh. I do use aggressive pads which requires brake pressure modulation to avoid flat spotting the tires.
I run stock sized rotors in my Exige (2025-lbs with me in it), because I didn't want the extra unsprung, rotating mass of larger ones. (Also I am using 1" less wheel diameters than OEM so there isn't a lot of extra room.) But while the OEM pads were enough for the OEM tires...once I added stickier rubber, they weren't good enough. So I added Pagid RS42 pads and it brought the ratio of pedal pressure to stopping power right back up to what I liked. (There are even more aggressive pads of course, but the RS42 still has decent low-temperature operation and rotor wear rate, and I street drive it occasionally so I think they were the best choice for me.) I run Motul 600 fluid even though I probably don't need to, just for the peace of mind.
People always ask me if my brakes need repair work, because they squeal a bit when street driven. No. No they definitely do not. I haven't run with ANY other production street legal car on DOT tires that will out-brake it in my sixteen years of doing HPDE.
Thank you sooo much for making a video in response to my comment.This question has been in my mind for years and now I got an answer from one of my favourite TH-camrs.Your channel is brilliant and deserves more views,keep going, great work!
No, thank you for asking such a good question that helped me realize there's a video behind this.
Excellent presentation, as far as he went....see, one must also take into account the shape of the contact patch of the tire on the road. Skinny tires have an elongated (front to back) patch while wide tires have the opposite, which is a wider contact patch. This is critical on motorcycles especially. A thin contact patch will, because the tire is elastic, under hard/extreme friction will cause the tire to "ripple" making the bottom of the tire the shape of a sine wave. Reducing contact with the road while a wide tire with it's wider contact patch will deform much less, giving better "stiction". And worthy of note, no matter what size/shape of tire, the contact patch area remains the same. The shape will be different but the surface area contacting the ground will be the same. I wish he'd have added this information to the video as it is not a minor consideration but a major factor in handling and braking and acceleration. I give the video a thumbs up because everything he said was spot on correct, just incomplete so in school grade terms, an A minus.
Yes, its amazing the number of people who believe that a 2X wider tire will have a 2X larger contact patch area! Even the purported engineers are getting it wrong!
My man just saved me from having to decide whether I want to buy a performance package with a big brake option. Thank you!
I've never wanted to upgrade to larger rotors for increased stopping power. I've always (intuitively I guess) known that the purpose was to have greater surface area to increase heat dissipation to reduce the chances of degradation of stopping power due to overheating and/or damage. All brakes can lock up your tires (assuming no anti-lock) so they all have plenty of force necessary to stop you as quick as possible. Losing traction on the road directly affects stopping distance. Maintaining traction is how you stop faster.
Most modern brakes can lock up your tires...but certainly not ALL brakes.
I understand what you're saying but why do race cars not just run tiny rotors? Because big ones stop them faster along with bigger tyres.
@@cedric1138 so you are saying that you don't actually get what I am saying. Read again. I explain the main purpose of larger rotors.
@@dougsholly9323 I read it, heat, segregation etc etc, all in all it boils down to one thing - they stop you faster.
@@cedric1138 did you watch the video? I don't understand why you are dismissing all of this.
Tyre pressure has just as an important role to play. I must say, my car with a 325mm rotor is a better & more sure footed stopping car than with the 298mm rotor both on a 245 40 18 tyre/rim @40psi operating temp. Thankyou for another excellent series.
Falcon XR6 owner?
One thing I think u forget to mention is bigger brakes (rotor) will have longer arm of force, thus creating more brake torque. However, for most modern production cars, the factory brake is sufficient and can break the traction of tires during heavy braking. Simply upgrading the brake may not shorten the brake distance during heavy braking.
I remember there was a test by a media in China. They compared two Civics, one with factory brakes and the other have high performance Endless BBK. After initial tests, the one with Endless actually performs slightly worse than the factory one (likely due to heavier suspension weight from the brake kit). However, what makes bbk stand out is repeated braking. The factory brakes experience serious brake fade after multiple brake tests but the Endless BBK still performs just fine.
It is more likely the friction material differences is what was the cause rather than weight differences.
The upgraded pads sometimes need to be hot to work best. That's been known for years. And yes the continue to stop better with more use instead of fading like oem pads
@@danc2014 It really depends on the car, mostly the weight of the car. I've never experienced brake fade in my Datsun 510 and trust me, I've driven the piss out of it. There is absolutely no reason to "upgrade" your brakes from stock when you have a car that stops from 60mph in 70 feet.
I have wondered why this is for more than a decade, and couldn't find a good explanation. This is it. Thank you!!!
When it comes to larger breaks for track use one factor wasn't mentioned. Modulation. With larger rotors creating more leverage modulation at the limit of traction becomes much easier. Breaking on the limit is where a lot of time can be made up followed by trail breaking through a corner which both take finesse and larger rotors along with pads\calipers make this much easier. Great videos!
you are saying that the further the BRAKE pad is from the axle, the less force is required to generate the same BRAKING torque on the axle? If that is desirable, then why are racing cars not set up to reduce the force required to actuate the BRAKES to a minimum? In fact we find that GT3 drivers expressed that BRAKE pedal stiffness was set largely by personal preference when its adjustment was possible.
But, can that added modulation benefit outweigh the addition of unsprung, rotational mass? I'm of the opinion that it can't.
@@joelambert7128 I never said less force was required. With smaller rotors the window between maximum braking before lockup and complete lockup is smaller meaning your modulation on the edge is harder to control. With larger ones that window is bigger and easier to modulate on the edge of traction.
That's for motorcycles. Not cars. You have four wheels. And you control all four brakes with one foot. That's why ABS is allowed in professional racing. Cos it's the same foot your ancestors used to ride a horse or drive a horse cart. You don't have a high tech foot that can control brakes on a car, it won't happen, get over it, whatever you think you have, you don't, without ABS, a motorcycle will leave you in the dust
Brakes are spelled brakes not breaks. Do you know the difference between two, to, and too?
This is what I’ve been telling people. Suspension and tires are better brake upgrades than brakes themselves. Now I know the science to back it up! Thank you!
Suspension and tires upgrade is not better way because stock brakes with upgraded suspension and tires will burn out very fast and you may loose brakes completely, so this is very dangerous upgrade. When you upgrade brakes only then braking performance will increase and burning out brakes will be even less likely then on stock setup.
This is total BS that by upgrading brakes alone will not increase braking efficiency.
Enlarging tires alone beyond manufacture specs will generate higher ware on suspension.
Even replacing old brakes with new parts is increasing braking performance, not mentioning about installing larger ones
It is true that if you want to capitalize on brakes upgrade suspension and tires should be upgraded too, but safer way is to upgrade brakes first.
Don't believe this video. It's not really accurate. If your brakes won't "lock up" the wheels and cause the tires to skid... then you could do with "better" brakes, unless your wheels are very narrow and skid very easily... in which case you THEN need wider tires. This video is an over-complication of a simple concept and the fundamental premise isn't correct.
@@sawomirmiszczak134 You mean the more stupid way is to upgrade brakes first because you will activate ABS even with the stock brakes. With larger brakes and everything else standard, you would only activate ABS faster.
@@jkliao6486 I was talking about heat, with better tires and suspension stock brakes would over heat very quickly, and this may lead to dangerous reduction of braking force.
And i say it again, even with replaced braking discs and pads for new you can gain couple meters comparing to old/used pads and discs. So the stupid way is to think that upgrading brakes won't do anything, it will.
@@sawomirmiszczak134 It will NOT. If you don't have the grip on your tires, you can't even overheat the brake. Your tires would give up first. Which is why you never upgrade your brake alone to improve your lap time. If you are talking about daily driving, then it's even more pointless to upgrade brake with stock tires and suspension. As for worn pads, that's about proper vehicle maintenance. When sth wears down, you replace them. Just like tires, engine oil, washer fluid and even fuel, you run out of that, you replace that on your car. You don't have to actively replacing your new brake pads with bigger ones to improve your vehicle stopping power. It won't do anything AT ALL. If anything, you probably reduce your vehicle's stopping power because now you need bigger alloy wheels that are much heavier. The next thing you know, your vehicle becomes a flat tire collector with those low profile tires.
It should be noted that increasing the friction of the tires (eg: wider tires, stickier rubber) will increase the amount of heat being generated at maximum braking as the brakes can withstand more force before lockup.
and your stopping distance will shorten
I love the amount of reserch you must do for your videos and the way you can present the facts in a form that regular guys can understand. The fact is that most modern vehicles equipped with EBD and ABS, the ABS kicks in if you stamp on the brake pedal so it obvious the tyres are the limiting factor for single brake applications. If you are a track guy or towing heavy loads you obviously benefit from better heat dissapation, the other factor is that larger calipers and discs makes braking more predictable with better "feel" over a wider temperature range. You have remember that many race car series do not allow ABS so this is important.
The other factor is that most regular vehicles have single piston, sliding calipers for cost reasons, whereas "perfomance" brakes have multiple opposing pistons to provide higher force and a more consistent brake pad application. One question, is it fact or fiction that you can boil the brake fulid in the calipers to a point where you are relying on compressible brake gas rather than hydraulic / liquid brake fluid? I experienced this in some of my older cars where the pedal went to the floor after some serious repeated braking but recovered fine once things had cooled down.
Yup. F1 cars have smaller breaks that some would expect. But the cars have much larger tires and their breaks can tolerate much more friction and heat.
I love your videos by the way. ✌️
So true F1 priorice tyre wall to been used as suspension than bigger brakes. I'm pretty sure they know what they're doing.
And before regulations the brakes were the smallest possible without compromising to get more tyre deformation benefits.
Explaining car related physics, you are doing a marvelous job!
That's why they makes sense on motorcycles, particularly at the front, since that's the brake you use more often. I remember when I had a two-stroke 125 sportsbike, going flat out on downhill twisted roads I had to use the rear brake to compensate for the almost non-existent engine break. Sometimes after 10 or more miles downhill, I had to stop for a couple of minutes to let the rear break cool because it started to feel as if it generated friction without breaking. Despite breaking most of the time with the 320mm floating front disk, the 220mm one caliper rear disc was the one affected, never had a problem with the front one, not even at the race track.
im glad you brought that up. I had the same issue when rallying my sports cars down hills.
When your materials heat up they expand. the rotor expands as well as your pads expand. even the caliper expands. They dont expand a lot, mind you, but eventually as everything heats up and expands, its as you said, you are braking without actually braking. by stopping for a few minutes and letting the brakes cool off, they contract back to normal size.
Well on track those 30hp street 125’s are so heavy that we actually destroy the front brake a lot on stop&go types track.
Lots of front discs we see deeply cracking between cooling drills.
@@Dstructeur1 these guys might have a better rotor for you, sorry youtube dont allow links anymore it seems. Look up brake tech. They make great aftermarket motorcycle rotors
@@blue03r6 We mostly use Brembo’s series Oro discs, which are among the bests available, so I doubt there really is a fix to this inconvenience sadly.
Single front disc is a weak point by itself, but 2 discs setups are much heavier and would level down actual bike performance.
Maybe the 4-small rotors from Beringer for front end might be a fix, but would still be hard/impossible to have homologated in any racing division and would still weight a bit more than acceptable although reducing inertia induced by 2 huge rotors.
@@Dstructeur1 those brembo's are solid all around. look up the cobraMX discs from braketech. there cut out all over to make them super light. they look like they'd weigh half of that brembo
Interesting. I upgraded my rotors from 270 to 290mm, same caliper, same pads and same tyres. Stopping distance when from about 48m to 35m, cold and both and similar hot.
Interestingly the force on the pedal to get the same stoppage went down a lot and the band from slowing to locking widened, so the smaller rotors either didn't stop good or fully locked with little threshold on pedal force between the 2. The larger diameter rotors widened this a lot so that I can modulate the pedal much easier without the fear of instant lock up in a panic stop.
I could be wrong but this would be the mechanical lever advantage increase? Like going from pedal back brakes on a BMX to conventional rim caliper type.
My upgrade is a very minor bolt on one. It's far more common to go for the twin piston setup for the front from the later models. It's pad is more than twice the size, rotor is 296mm so pretty much the same diameter. The thickness goes from 23mm to 28mm. This upgrade makes an enormous difference cold and even more so hot.
I think there is more to it than just heat dissipation. Probably leverage, heat, caliper rigidity, pad pressure uniformity, glazing, rotor distortion etc...
What probably happened is that your new rotors lock the wheels faster. While both locked the wheels, let's say the new brakes lock them 0.5 seconds faster, that results in reduced braking distances because optimal deceleration is reached faster
@@StragTacGaming you're wrong. It's also a common misconception of "why upgrade your brakes I can lock up my wheels fine..." Locking brakes is the worst way to slow down. Peak braking efficiency is where you can apply the most braking pressure while not skidding. Bigger brakes have more leverage so require less pedal effort to apply braking force. This means it's easier to ride the limit of traction. This is also why "wide tyres help braking" because you can push harder before it skids. A bigger brake on the wider tyre will still brake better.
You can look at it as stock brakes are a 3 position switch - off/slowing/emergency and big brakes are a 7 position switch and you'll understand the control you have
@@JackoTJK My comment was considering an ABS-equipped car. When you are able to lock the wheels earlier, the ABS can work to modulate the braking pressure earlier. The best deceleration is provided under slight lock (ABS does this perfectly), just like how the best acceleration is provided under slight slip, and having a bit of slip on a launch will always be faster than having 0 slip
@@StragTacGaming ABS is less efficient than manually modulating if you have any skill which is why most racecars don't have ABS.
But. It doesn't matter. ABS works by taking pressure out of the brakes regardless of pedal position when it detects a lockup. Better brakes means it will work less because they are working better so you're less likely to lock them up. You can push closer to the limit with only the better pedal feel.
I'll say it again. Good brakes does NOT mean they lock up. They are in fact the WORST brakes if you did a side by side stopping distance comparison. The best brakes give more braking with less pedal effort but have good feel from barely touching to full blown emergency
@@JackoTJK ABS is better than threshold braking. It's a common misconception that you can brake better than ABS. See Engineering Explained's video about it: th-cam.com/video/G-GEUkiMuLk/w-d-xo.html
And race cars do in fact have ABS. For example GT3 cars. Only series like F1 have ABS banned because it makes it too easy
Based on my experience with motorcycles, I figured the answer was that your brakes are going to be able to lock up the wheels anyway, so the contact patch was the limiting factor
Locking the front wheel on motorcycle is always a exciting time
There is a direct correlation between additional tire patch width and increased grip (all 4 directions) - all other things being equal. This correlation gives you between 20% and 60% additional grip for additional tire patch. The example I use is going from a 245 section width tire to a 275 will increase tire patch by about 12%, take that and multiply that times 40% (the average) and you are getting about 5% more grip. That 5% may seem minor, but if your car stops from 60mph in 110 feet, you just dropped it to 105; if your car corners at .95g, now it should be about 1.00g. I've seen too many articles and videos of people buying/upgrading cars with carbon ceramic brake rotors and bitching about how their car stops the same as the ones with the iron rotors, which proves that tire patch is more important that brake rotor material, number of pistons, or size of your rotors.
Another item people overlook too often is that front brakes provide about 70% of a car's stopping power due to weight transfer during braking - upgrading rear brakes (unless they are tiny or drums), does almost nothing to shorten braking distances (even in rear engine cars). So when someone has 15" brakes all around, the rears are just for looks, the 13" would be more than adequate.
Lastly, most front engine cars benefit from a "square" tire setup (same size on all 4 corners) due to having 50% or more weight up front. BMW for years liked to stagger the tire sizes, even though their cars were 50:50 weight biased give or take. 225/255 was very common and hurt braking and cornering quite a bit - anyone who raced these cars always ran a 255 up front to balance out the rear 255, wider on all 4 was even better.
The flaw in your explanation is that the tire patch is always the same size (area). You can change the relative shape of the patch with a wider tire, but not its size (area)!
Okay, the video is 16 minutes long. Y'all start commenting before 15 minutes after it's uploaded and I'm gonna know that you didn't watch the video 😤
maybe we commented while continuing to watch?
You’re explanations of the concepts at work here with brakes and tire grip are just the best. Thank you so much. Love the channel too.
Can’t wait for more of your content.
Good explanation, but one point missed. If you are upgrading to larger diameter rotor with appropriate caliper and pad. In this case even the braking force on pad might be the same as before, the brake torque is still higher measured on the hub, because of the larger radius.
Thank you for pointing that out! Was looking for this comment!
It is, but it does not contribute to total braking distance on its own. Stock brakes already have enough friction to reach above maximum grip on your tires. However with a bigger brake rotor with upgraded calipers and pads the brake pedal feeling will be different, because the amount of pressure needed on the brake pedal to achieve above maximum grip on your tires is less as a result of increased brake torque. This means that slaming brakes all the way on a stock car and a car with upgraded brakes will result in same (or almost same) braking distance, but pushing your brake pedal to, lets say, 10% of it's travel will have greater effect on a car with bigger brakes. (assuming everything else in said cars is the same, which is almost never the case)
Brake kits with larger rotors often have more individual pots, so can apply more 'normal' force. This may not actually help much if the standard brakes can lock the wheels at typical driving speeds. However it will help if you've increased the power of the vehicle, or fitted wider tires!
An area missed by this analysis is that a custom brake kit may have better mechanical function. What do I mean by that? Better pedal feel, more progressive braking force. These may make the experience of braking a whole lot more predictable and pleasant. This really does seem to be the case with (for e.g) Brembo kits - in some cases the actual braking distance improvement might be really small, but the *experience* means you have confidence to mash them and achieve much better stopping!
You need to stop your tire from spinning or need to stop your car? 😂
Thank you very much for this. After studying Automotive technology in my younger days. My teacher never talked about braking system like this apart from how they worked and different types . This for me is much more informative and educational.
This is a great explanation covering a lot of basics.
The other big reason why bigger breaks don't stop a car faster is stock cars are all designed with breaks that can overcome tire-friction's forces and cause wheel lock up with maximum applied pressure. ABS then helps prevent skidding, but it still activates because breaking force can become higher than tire-force in every stock car manufactured. Thus in real-world practice suspension design and tire size are the only real factors influence stopping distance with cold breaks. Which if you are cursing down the highway or driving about town, your breaks are gonna be local air temperature or close to it, thus "cold."
And suspension design is NOT to be understated in its role given a good management of weight transfer can maintain more weight on the rear tires, thus increasing total contact pressure over all 4 wheels, leading to a notably higher traction. If weight transfer is extreme because a soft suspension that "dives," while yes the front tires will load with much higher pressure thus much higher traction, the rear tires could lose so much "weight" they fall into the point where rubber rapidly starts to lose friction with reduced normal force. Thus the car's total available traction can dramatically decrease, as much as I think 30-40%. And as mentioned, rubber has a point where any additional load doesn't generate a noticeable increased in friction so the front's very high weight transfer will not compensate for loss of rear wheel traction past a point. Worse yet is if the rear tires unload badly enough, the car can become highly unstable, and subject to "oversteer" (aka spin out) if its not moving PERFECTLY straight while breaking hard. Even the smallest turn of the steering wheel could cause a spin out in this condition This is why manufactures will actually go through a lot of trouble to balance ride smoothness with shock/spring stiffness to prevent even road cars from "diving" under heavy breaking as much as they reasonably can.
In fact as consumers become aware that well-tuned suspensions make for much more controllable, thus safer cars, we need a very large increase in tolerance for a slightly firmer ride in exchange for that safety. Which is one of the reason why the old soft suspension street cars that use to scrape their bumpers when breaking have all but vanished from the market.
God I love this channel I have never actually driven a car but the physics behind them are immaculate please never stop
Not only are they immaculate, but they are also very approximate in a lot of ways. So many variables. Flex, tolerance, etc. Its totally a case where art and science meet.
@@Nbomber It's also, unfortunately, a case where people often try to use the art of things to negate scientific fact eg. exhaust diameter and the idea of backpressure. Some things are absolutely a feel it out and use experience kinda thing, and many things that involve science can only be approximated... but some people take that as license to bin the science entirely and put on their big-boy anti-intellectual pants and very loudly make claims about things they refuse to understand because they've heard too much "common sense".... I'll admit I've got a chip on my block about this specific issue, but I'm basically just adding that you're right that some things have a feel to them and can't be modeled exactly, but some people take that a step further and just insist that you can't "know" anything... which philosophically is fair, but from an engineering standpoint, yeah.. you absolutely can.
(Again, not contradicting you, I agree with what you've said.. just adding a little nuance.)
(... but gods, is the internet discussion around exhaust diameter really absurdly heated for a subject that while hard to model exactly... conforms perfectly to a set of thoroughly established rules, give or take a non-negligible margin for real world variability. The discussion on that topic is a frustrating quagmire.)
@@LifeInJambles nah i hear you man, and you are right. Especially when somebody says "and this is my patented special method of doing......". They exist in every feild though.
you hit the nail on the head about the philosophical part though. Engineering is in a large part the science of compromise. With everything being "good enough". Tolerances being how tight the margin is for wether something is good enough or not.
Theoretically, everything in a car is loose and sloppy, not square, not straight, not flat, not clean, not round, not balanced, etc.
@@LifeInJambles actually, i remember there being some "wisdom" about running subaru engines with loose piston ring gaps, for some reason (i think it was subaru engines). Obviously this is pretty idiotic, but a lot of people took it as gospel.
A larger pad has more mechanical advantage essentially. If you are applying force further from the wheels axis, you get better stopping torque.
But extra "stopping torque" beyond what's required to lock up the wheels is irrelevant. The limiting factor in reducing stopping distance is almost always grip.
@@itsasecret2298 Right but without driving every single vehicle ever made how do we know which vehicles need more stopping power and which need more traction? This is an extremely case by case basis.
@@Saddedude That is simple, every manufactor puts in a big enough braking system, thats why every car has ABS.
Extra mechanical advantage means nothing when you're already able to cause movement with a smaller lever.
@@Saddedude There's really nothing case by case about this.
Braking systems in every mass produced consumer vehicle are capable of locking up the wheels. If they aren't on any individual vehicle that's a sign of mechanical failure which needs to be repaired.
One of the purposes of a big brake kit is to get the calipers further away from the center of your wheel.
You may not increase the force of the pads on the disks, but you are creating a larger torque. Torque is the product of force and distance. Torque is what actually slows your car down
No your upgrading to big brakes (unless it’s a 50s drum brake) to decrease heat. Your stock single piston caliper can lock your wheels, just not for long
Brake torque doesn't matter as long as your brakes are strong enough to lock the tires (which they all are).
@@prdoyle fair point, but as soon as you increase mass you're going to need more torque. Especially in something like a truck hauling material. 1st gen Toyota Tundras, for example, have notoriously under-powered brakes
I used to think it was because for larger disc brakes, the brake calliper would be attached at a point further away from the axis of rotation and hence have lower torque, needing lesser force to stop the wheel rotation than if the brake calliper was nearer to the axis of rotation. Well thanks for the explanation!
Thanks for putting a finer point on our understanding of brake distance vs tire and brake size. I track a car(s) and upgrade the pads FIRST and as I get better and it is a bit amazing to be stopped due to red flag have SMOKE pouring out of my wheels and know I hadn't given up any braking force yet...When I get fast enough to make my brakes cry out in pain I will invest in those big brakes.
This guy is great at describing complex concepts in simple terms. Interesting and very digestible.
If it weren't for your content, my project car would be where it was. I appreciate your compassion of sharing your knowledge man.
What you DIDN'T go into is that all tires have a different compound, and therefore a different µ. A case in point, back when "retreaded" tires were more common, they were barred from certain races, not because they are more prone to self-destruct, but because they were a "softer" rubber, and has more grip for the same size and tread pattern.
Yeah he missed that and also the fact that wider tires don't increase the contact patch proportionally, the patch will get less long longitudinally. Contact patches are two dimensional.
Thank you for the second video, it is appreciated. 😁
Brakes and tires should be matched to one another, or you could get into trouble.
For example, bigger diameter tires require bigger brakes ... something off-roaders sometimes forget.
Something like a 3 ton Jeep going down the highway on 40" tires and with bottle top caps for brake discs is incredibly dangerous !
If tyres pressure is same, wider tyre will have similar contact surface. If braking pads friction force is the same larger diameter brakes discs will generates greater braking torque.
Hello D4A!
Thx a lot for this video. It's amazing how much knowledge you share with us. I study mechanical engineering, and even your most theoretical videos are much practical and entertaining. Salute from Brazil! 🤘🏼
Nobody's mentioned that depending on the car, if you have a lot of negative camber, a wider tire isn't doing anything for braking since some of the outer edge won't be touching the ground anyway.
Yes, You are very much right
Yes but bigger brakes wouldn't help either becaus the problem isn't braking force but grip (I am aware that is not what you said, i am just clarifying).
I asked a Dunlop engineer why slick tires has higher grip a few years ago.
His answer is similar to your explanation.
He said slick tire can grab on to more surface imperfection.
Slicks effectively work because they're softer and people typically go with a wider Tire with slicks but the main reason they work better is because they're softer regular passenger vehicle tires are designed to have a certain amount of rigidity to them especially all season tires as opposed to summer only tires so that they're effective in a wider range of temperatures whereas slicks are designed to be softer and get even softer and stickier upon heating up if you've ever actually use slicks when people do burnouts and then are able to get significantly better times it's because of the traction on their tires has increased now that the tires are effectively sticky and softer
@@altaccount3760 If the roads were never wet, slicks would be the best choice.
@@rangersmith4652 in a place with controlled climate to otherwise they would only be good during a certain temperature range and also softer tires make for weaker tires part of that rigidity in commercial tires would be for penetration resistance and additional suspension absorption as your tires act as a added layer of suspension on your car where slicks sort of fail at that but yeah you just have to warm them up in the morning with a good old burnout and youd be on your way xD but yea all roads would have to be like highways and they'd need to be swept
@@rangersmith4652 also the rigidity from commercial tires adds to the tire life along with on the other side the softness of the slicks decreases the slick's life
@@altaccount3760 But slicks don't have to use a soft compound. They almost always do because they're not sold as street tires, just racing tires, so ultimate grip is valued over longevity.
a friend from long ago, told how on a very wet motorway/freeway, he was having trouble with traction due to aquaplaning as he had wide as tyres,, and was amazed when a citroen cv2 easily overtook him..
in my experience , narrow tyres on gravel roads, wet or dry, is like driving on tarseal, compared to the wider tyres I swapped from..
I don't know how you can continually spit out useful information sentence after sentence non stop. Impressive.
correction: surface are IS in the formula *twice*, you just don't see it because the coefficient of friction multiplies by that area, while the downward force divides by that area, thus the area does not show up in the abridged version of that formula.
also your explanation of why thin tires perform better on wet conditions is not entirely correct.
water does not care about the distance, it cares about displacement.
wider tires have more displacement, that displacement generates buoyancy, which works against the gravitational force acting on said tires, which reduces the normal force, thus decreasing friction.
If the two area values cancel out, then the formula is not "abridged" without them. It rightfully doesn't need them at all. Area never need be considered in the first place.
A larger disk has also a larger radius which has a much better leverage - you kinda forgot this aspect.
I discussed this with one of my patrons over on patreon. Yes that's true but not in the sense that it's true on bicyciles whre you have 26, 27, 28 inch wheels and the distance between discs and rim brakes is significant. In cars you are very much limited by the amount of how much you can increase the disc. We're talking about a noticeable amount of surface area but only a few centimeters of diameter. This added leverage is negligible when you put it against the masses and forces present in an average car.
@@d4a Re bicycles - I thought about a 26 inch front wheel with either 6 inch or 8 inch disk rotor. It makes a huge difference because of the higher leverage you don't need less braking pressure on the pads.
But totally agree - just from friction point of view, higher surface area on brake pads do not help (unless you consider the heat dissipation).
As always - great stuff !
a larger radius rotor also typically has more mass to it than a smaller rotor, and therefore requires more force to stop it as well. larger mass, longer stopping distance... going big isnt necessarily of benefit.
@@Alkivar You need physics lesson - the add disk rotor weight is negligible if you take a car wheel into account ... 🙂
@@Alkivar Not to speak of a MTB disk rotor ...
Bigger brakes are better then smaller brakes
No they are worse
Biger disks and pads also contribute alot to breaking faster and more efficient. bigger disks mean bigger pads, which translates to more surface area and bigger breaking momentum/torque (because of the size). Also bigger contact area dissipates the friction heat more evenly, which means breaks dont heat up so much and the ware of the pads is smaller :)
Been in the car business / racing and never even really thought about this. Just assumed bigger better. Thank you so much for your video of and the way you explained it is beautifully understandable, appreciate it! New subscriber going forward can't wait to watch more.
Finally, someone is talking sense, thank you.
Bigger brakes means more sustainable braking
Yes!
i am not here to disagree, because all of these make sense and of course play a role. But the larger in diameter the brake disc is and the bigger the brake pad size, will have much more friction area and that way, we can apply more force than previously and get better results. this video only talks about applying the same force. rather than in reality, installing a larger rotor, and bigger caliper, often means the master cylinder will be also larger so you can apply more pressure onto the surface area. and that is without taking into consideration fixed calipers versus floating calipers and the advantages on them.
"we can apply more force than previously and get better results."
No. For one very simple reason: It does not matter how much torque you theoretically could apply for braking if the tires start slipping.
@@ABaumstumpf you clearly miss the point.
@@TheRealBhuado "you clearly miss the point."
Says the person that claims you could apply more braking force than already locking up the tires.....
@@TheRealBhuado You clearly don't understand how brakes work. But have at it, waste your money on snake-oil.
A bigger disk diameter for more powerful braking is not really about more surface contact, but the pad contact being further from the center of the hub, so it is a longer lever, and does greatly increase stopping power,---if the tires hold the road surface. The flip side is heat. More surface speed is had by the bigger disk, (more distance around the circle for the same rpm.), so it will generate more heat. All coefficients of friction being the same, the amount of heat developed, (before dissipation), shows the braking power nicely. But the friction of the tire on the ground has to be more than the braking so the tire does not lock up. So wider tires are used for applications of aggressive braking, (racing).
From different road surface condition, (from ice to dry clean pavement), different tires and different braking systems, to say the tires are the difference and not the brakes for distance is a bad statement. I am sure many car tests were dine with similar car weight, the same tires, and different performing brakes, (the only factor of difference), and if all the tires don't skid 100% of the time when braking, you will have different stopping distances.
Fantastic explanation. Actually answers the question why the C8 corvette has bigger brakes in the rear, than it has in the front
Considering you have sufficient grip, a larger rotor will provide more leverage with the same amount of brake pressure
He didn't say that, but for better explanation you might want to watch a video he uploaded defending this type of argument ❤️
Is it me or did he not mention the increased leverage gained from bigger disc rotors?
He's addressed it in another comment thread. It ends up being basically irrelevant.
I think the argument is that if you can already lock up your wheels (i.e. ABS engages) then you're getting all the braking the car is capable of without upgrading tyres, suspension etc.
But yes, bigger brakes do give a bigger lever arm so the calipers don't need to squeeze as tightly for the same amount of deceleration. Doesn't lower stopping distance appreciably though.
He never stated that braking force isn’t actually bigger in real life scenario, but it doesn’t matter as standard brakes can lockup tires, so you’re not limited by braking force, but by tire grip. Of course it’s different when you race, then you put beefier slicks and just maybe then you’d be limited by brake force, but I still doubt it. Certainly limited by brake fade, but that’s not the point.
@@driv3ver yeah and no, if you ride motorbikes you’ll quickly see an extra 40mm on the front rotor makes a massive difference, I know he’s talking cars but he rides aswell.
@@merkel2750 That’s only if OEM system is lacking. I’ve been riding years ago too. What you’ll always notice with bigger discs is that you need lees pedal or lever travel for the same stopping strength, but still threshold is the same at tire’s grip level. Which leads to less precise braking, because very little force applied on pedal or lever will initiate high brake force and doesn’t let you modulate that well. You’ll be locking up with let’s say 50% travel instead of 90%, so you won’t be that precise. In the end bigger disc will make you feel like your brakes are better, but if you compare stopping distance it will be the same or worse (brake bias!). I’m occasionally driving on track days, and if OEM system is good, then even for track racing it’s enough to only maintain it well, put good brake fluid, steel braided lines, good rotors and racing pads. Unless you’re getting much more HP than stock then BBK may be the way to go due to heat issues.
Also for most people
Handbrake shoes are a lifetime part or only need replacing when they have cracks or rot.
as they should never wear out really as the car should never be moving while its being engaged so it cant wear.
Many brake places will scam customers saying they need new handbrake pads and never put new ones on as those with 500,000km on them still at 95% thickness.
Play this on x1.5 and thank me later
Some thing you didnt metion is that Brakes are basically never the limiting factor. Even Stock Discs and pads can apply enough braking force to overcome the friction of the tires. As the normal force of the brakes is a changing variable by just pressing harder on the brake. the limiting factor on there is just how hard you can press the pedal (and how much its amplified) theoretically all the way to mechanical failure. That is why ABS or anti lock braking sytems exist. Once the brakes overcome the force the tires can actually apply to the ground, ABS limits your braking force to stop the tires from locking up.
2 reasons why tires shouldnt lock up:
1. you still have have control (locked up wheels cant steer)
2. static friction is alway higher than sliding friction
The theory just rolls off your tongue. Excellent explanation.
Definitely saving this one!
Whilst it will not shorten braking distance, it will allow you to repeat max braking more often, so still good for anything you want to track.
very clearly explained, on top of that, one of the most effective way to improve both braking and handling is weight reduction
This is a very interesting discussion of the F=MU x N, sorry I couldn’t use the proper symbol for coefficient of friction. May I add that, while it is understandable that bigger brakes will not stop a modern ABS equipped car faster, bigger (greater coefficient of friction) brakes will stop an older car, especially one originally equipped with organic shoes and drums all around, faster and this is reduction in stopping distance is of course enhanced with greater tire contact area.
Anyway, getting back to the discussion of the F=MU x N equation and how it does not apply to tires (at least not in a linear fashion), I thought it might be interesting to discuss the topic of how weight transfer, biased toward a particular end of a chassis, might manifest itself in the cornering behavior of that chassis. Thank you for taking the time to present such an interesting TH-cam channel, your efforts are appreciated.
We had a Car content youtuber that work as a tuner and worked on VW designing brakes, and he had a tough time explaining the same thing, bigger brakes don't make you stop faster. At first he tried to explain using physics but people were not satisfied so he had to literally put into test by recording braking times with original brakes and bigger brakes, the times were the same. And then he made another video, but upgrading only the tires, the results were a lot better. And till this day there are people that do not believe him, even after watching his videos, crazy
The equation is actually Torque = 2•μ•Force•Radius, where the radius is the average radius of the pad. Increasing the radius allows for a greater torque capacity, of which a negative torque is what slows the vehicle.
There was a dirt bike (motorcycle) called the "ATK" developed by Horst Lietiner. He mounted a smaller diameter rear brake dist on the counter-shaft sprocket shaft (front sprocket). The small dis would spin faster than a disk on the rear wheel, but he calculated the surface speed to be the same, (so the heat would be the same). It heated up faster and tended to discolor, (something not seen on the wheels of a dirt bike disk). There was not as much surface area and material to dissipate the heat as well. Today, my modern dirt bike has a bigger disk yet,---and it is way too powerful for me,---until the tire slips. You do a good vid.
I was on the highway a few months ago on the way to the beach, it was raining and traffic was backing up, all of a sudden traffic came to a complete stop, I Had to use a lot of brake to stop quickly, I have upgraded wheels and tires, they are lighter and wider, I have the Michelin pilot sport all seasons and I remember how effectively they worked, the car behind me had to swerve into the other land to avoid hitting me from behind, I’ve upgraded my rotors and pads also but i credit the tires for helping me stop so quickly.
You never first saw my comment here all you said here was entirely right, thus it really takes the initiative over non and reality, I could agree with this also as your second video, Rim brakes can be increased their friction due that they can lock more, I hate to do it but I need to do it in order to prevent me from accident.
Big brakes do two things. Look good, and provide increased potential heat dissipation, which helps reduce brake fade during repeated hard braking (like on track day.) That's it.
11:50 this is not a rubber ball! Mostly air is compressed, but I know that it doesn't change the nature of the argument. But other than that, the video is absolutely fantastic. I am a physicist and it never ceases to amaze me how much different the apparent same world of engineering is from physics. Very informative, many thanks!
The best explanation of this subject that I have come across! There's so much science and physics involved with this, yet you did a commendable job of explaining it to us common folk in terms we can understand.🤩 Thank you.
With 35x12.5 R15 tyres on my ancient vehicle, it stops incredibly good, even when the brakes are somewhat old. I could not believe the difference between the stopping capabilities between the vehicle with P215/75 R15 tyres. The offroad abilities of the 35x12.5 R15 tyres are also amazing. The only sacrifice I have is slightly slower take-off, and a tiny bit less fuel economy that was rectified when I regeared the differentials. I can never go back to driving a worthless, urban, manicured road, street car, especially where I live.
also motorcycles usually have more disc surface/weight so even with similar cooling they would overheat later
Indeed, You buy bigger brakes for two main reasons, better modulation and feel and better resistance to fade. But they also looks awesome 🙂