This is something I’ve tried to tell people for years. Easily one of the best bang for buck modifications you can make to your car. Every time I modify a car, one of my first purchases is an upgraded rear anti-roll bar.
It's good for smooth roads... It makes the ride much rougher on bad roads though. The double edged sword of stiffness. It does take away some comfort. Depending on where you live, If comfort is the priority, don't do it. Otherwise it definitely helps in cornering handling and stability
I thought that was common sense, it’s pretty well known in 4x4 when you raise the car more than 3 inches to not just lose all steering or rolling over in the first sharp turn
Funny story, this trick is how I used to beat the pants off of people in the old video game Gran Tourismo. It was billed as a "driving simulator" and bragged about a realistic physics engine. That's what got me interested in it, and I wasn't disappointed. In that old game, sway bars and lightening were the under appreciated modifications that could turn a boring compact into a consistent winner. My general tactic for cheapest results was to fit the "racing" level bars, both front and rear. These offered the greatest adjustment range, and I'd start with the front on full soft, and the rear midway. I'd consistently beat far more powerful cars with little effort. It would rotate very fast in low speed turns, fairly neutral in faster turns, and allowed full power on corner exits a lot earlier than my overpowered, understeering, rear drive competitors. Works in real life too.
The ND Mazda MX-5 might be one of the exceptions among modern performance cars, very soft suspension setup and pretty good handling balance from the factory.
It also benefits from 50-50 weight distribution and very low overall weight :) I would guess these factors allow it to have a soft suspension and maintain good dynamics
It's even better than that! It's true that the sway bar increases outer wheel load on the axle it's mounted at, reducing that axle's cornering grip. Additionally, it also increases wheel load on the diagonally opposed wheel on the other axle, as long as the body is stiff enough. So you are not just making one axle worse, you are making the other better! Good video! I'd love to hear your thoughts on horizontally mounted chassis dampers like the SARD motion control beam.
As the wise man once said: "even the worst suspension can be improved by preventing it from operating." Mostly necessary due to roll center and how high cars are. If you have a low car, or one with low center of gravity (EV?) may not be necessary? As the owner of a string of VW cars I always found it hilarious I was undoing the semi-independent trailing arm rear suspension. It's also neat when the torsion beam can house a splined torsion bar of varying specifications, without needing any linkages.
This is the exact problem I'm fighting, and while I found the answer myself through hours of research I'm glad to have the confidence of this video backing it.
I have a Pontiac Grand Prix. The suspension is exactly like a 68-72 GM A-Body (Chevelle, GTO, 442, GS). I did the poly bushings, cut one full coil from the front coils, added a 1" rear bar and gas shocks. The MOST PROFOUND result was replacing the stock 1" front bar with a 1-1/4 bar from a WS-6 Trans Am. The car rides firm but not harsh. However, it corners very well. It is fun to drive in twisty roads. The last change I need to make is to install a bump steer correction kit.
Fitting a stiffer sway bar at the rear on my normal cars has always made them just 2x more enjoyable to drive. They are boring cars by default, but this has always been the minimum for what I would change to my FWD super understeery cars.
Excellent presentation, sir. To your point, I have posted the fastest time at many SCCA autocross events over the past 14 seasons while running either an NB Miata with no rear sway bar, or a Subaru WRX with no front sway bar. I actually won the D Street class regionals in my 2017 WRX with no front sway bar and bone stock springs/ dampers. I only tuned the car balance with alignment, tire pressure, my right foot, and lots of second-hand knowledge from books about Autocross suspension theory (Dan Watson is one of my favs). After looking through your videos tonight, I’m looking certainly forward to adding your book to my collection next.
When VW worked to set their Nurburgring lap times for the MK2 Golf It was faster around the track with no front sway bar. The rear doesn't run a separate sway bar but the rear axle itself is effectively one.
Sway bars are good and easy modifications, just be careful. On one of my cars I went from a hollow 19 to a hollow 25mm in the rear (from the sportier trim level of the car) and it snapped the mounting point off the subframe after some excited driving. After re welding it stronger its snapped in new places about 5 more times and now I have to drop the subrame and reinforce everything for it lol. but if you have a car that isnt made of cheese it shouldnt be an issue
Yes you do see and read the fact that more unequally balanced left to right tires have less maximum grip potential, compared to more equally loaded tires. That’s what it’s all about!
Bought 2 of your books: One on aerodynamics and the other on argumentation & logical persuasion. Good stuff. I know you're not a fan of F1 and motor racing, but I forgive you 😉
Yep. I live in Brazil and we don't have easy access to performance stuff, everything is either too expensive or or outright impossible to find. I did the sway bar first in my Fiat Uno. The Uno is the first global car Fiat has ever made, released back in 1983. Here in Brazil it was sold from 1984 to 2013, only stopping production cuz airbags and ABS became mandatory in 2014 up cars. From 1997 and above the Uno became the cheapest car one coumd buy, lacked any luxury or performance. But up to 1996 there were fancier models and even sportive models like the Uno Turbo, one of the coolest hot hatches you could get in Brazil and Europe in the early 90s. Mine is a 2001 model, so a cheap, boring, economic car. That until I bought the sway bar from a Uno Turbo and installed in mine, it instantly begun handling like a kart lol. Since then I've given it a bigger engine, gigantic brakes and excelent tires, Recaro seats and so on. (It's way better than a Uno Turbo now) But yeah, the best bang for buck upgrade was the sway bar. Truly night and day difference! Since then I've upgraded my brother's mk4 Golf with sway bars from the R32 lol. And also my parent's very boring, very mundane Logan (sold here as a Renault, but actually a Dacia elsewhere). Here in Brazil they made a hot hatch version of the Sandero, simply called Sandero R.S. Actually tuned by the french Renault R.S division, it had beter brakes, insane tires, completely overhauled suspension, etc. Since the Logan is just a sedan version of the Sandero, I purchased the sway bar from the Sandero R.S and installed it in the Logan. Easily the best thing I ever did, it used to roll so much it was scary taking the highway with it. Now it stays put and I've chasen much better, much stronger cars around the mountain roads we have here. Hahaha
I've wondering to make my own rear swaybar for my mazda 2, but I don't know how to calculate what stiffness I need. I can just copy the design of a manufacturer, but as a junior engineer I'm more interested in how to design a proper anti roll bar. Also I find that my car has pretty neutral handling so I don't want to ruin it putting a stiff sway bar at the back.
You will find popery designing a rear sway bar to be immensely difficult. eg you will need C of G height, suspension roll centre heights, stiffness of springs, motion ratios of both the springs and proposed bar, etc. Better to copy a similar car as a starting point.
it's very hard (pun intended) to really overdo it, but maybe with a rear torsion beam you won't need as much. take measurements of the existin setup and calculate what you need to double the stiffness. I went with 4x stiffer myself
It was great info. Clear and concise as always. Good reassurance because I was building on information from racing sims up until this point and was not 100% sure this change is a great idea for the road. Anyways I have a Suzuki Swift/Cultus hatchback from 1997 which has quite noticable understeer in roundabouts even at normal speeds. These 1.0l models were not fitted with any sway bars and only the saloons and gti-s have one at the rear. So I sourced one from a saloon but had to realize the mounting points are not present on the underbody of the hatchback. At least now I go into the welding phase more confidently that it will have the desired effect and the modification will not have to be reverted.
I dont think what youre experiencing is understeer but... if you really want it then change the sway bar. Youre certainly not going to make it any worse thats for sure :D
Extremely nice video. I am building a drift E30 and i have fitted a rear sway bar (stock) because it wasn't choosed on the initial car. I have also fitted an inline 6 engine instead of the inline 4 it had and not changed anything about the front sway bar yet. I will try driving the car without sway bar in the rear as in drifting you want all the available traction on the rear. Thanks for your nice videos. Greetings from Greece!
There is another use for sway bars in handling too. Helping with reversing a turn. From my own experimentation, mostly in computer simulations, I totally agree. When I'm tuning a car, and dialing in the handling, usually I adjust only one end at a time unless both ends are radically off from what they should be. While I tend to like running the softest suspension and sway bars that will allow good handling, I have noticed that having less roll stiffness tends to have a negative impact on the balance of a car when transitioning right from a turn in one direction to a turn in the other direction. For relatively smooth race tracks that have tight windy bits with no strait in between turns of opposing directions, I tend to retune the balance with stiffer sway bars. I adjust them both stiffer together in order to maintain the balance of the car while reducing the time it takes for the car to settle out of the corner. This can, as pointed out in the video, make the car more skatey throughout most of the track, but if you offset the minimal time lost through simple turns by dramatically improving the time through a technical bit, it can be worth it. But again, as soft as you can go while getting the job done. If anyone wants to weigh in with something to expound on this, please feel free. This is just from my experience learning to tune in simulators like LFS(Live For Speed) which provides great freedom to experiment with the suspension. I find that what Julian Edgar said in the video to be true, and it fits my experience as stated above.
Thank you for saying this. This rings very true for us in the bmw community - i see alot of people putting very stiff springs on their car. These aftermarket coilovers: ruin ride quality compromise chassis in suspension mounting points (in particular this exacerbates issues on e46 and e36 3er chassis) sometimes cost far more than oe options provide minimal handling improvements over factory sport suspension options. But when you bring up that an upgraded antiroll bar will make a bigger difference you are shut down and told you dont have an understanding and that the coilovers are "worth it" - I dont know what is causing this, potentially marketing by coilover manufacturers. The other belief is that lower = better handling. It just doesn't but that's another issues.
I think the lower is better thing comes from modern race cars producing more downforce the closer they are to the floor, which obviously doesn't matter even slightly in a normal car context.
I think many people want coilovers because the ride height is adjustable to their aesthetic preferences. It's less about the performance improvement, and more about replacing old stuff with new and making the car look better. If you have a beat-up old E36, a cheap set of coilovers will still be an improvement from stock 30-year-old blown out shocks and springs. Personally, I would rather keep it simple with new shocks and lowering springs, but I understand the appeal.
Have done a bit of experimenting with the Chevy Cruze and autocross racing. Car started racing on stock suspension, then eibach lowering springs, then bolted a stiffening element to the rear twist beam, then got Koni yellow shocks for the rear, then got rear spring stuffers (rubber between coils) and finally the car began to rotate in the turns with 8 psi higher rear tire pressures vs front. This became my daily driver setup when not racing. The next incremental improvement [for autocross times] are the stiff spring option ISC coilovers, with 12k front and 10k rear springs, rear motion ratio 0.66. It rides terrible and gets into a harmonic on some roads while traveling at freeway speeds which bucks me like a bull ride. The car more easily rotates on the race track with less difference in rear vs. front tire pressure and less body roll. This season has more mods. I ran the calcs and got a set of 6.7k front springs to mate with the 10k rear springs giving a calculated frequencies of 1.9 front and 2.1 rear to try and achieve flat ride. The front shocks will be replaced with the standard ISC valving. Because of the soft front springs, I opted to get both the front and rear [adjustable] sway bars, front bar logic is to reduce body roll from the softer springs.
Great video! I have a question about this topic, I have a bmw e82 135i, which has very little (and not adjustable) camber at the front wheels and zero camber gain, putting the tires in a disadvantageous position when cornering hard, basically loading only the outside of the tire (which wears much faster than the outside). Some people in the forums suggest that fitting a stiffer front sway bar the reduction in body roll allows the tires to have better contact on the ground thus enabling them to produce more grip than with a softer bar. Do you think this could be the truth?
My car has 50:50 weight distribution and handle very neutral 😂 From this video I should do nothing. The only thing I can do to increase grip is better tires... I already have SportMaxxRT2😂
Legit the best video about swaybars. Not hard when most are just "fit my sponsors product" but you deliver again. I have applied a bunch of things you cover and friends with more 'sporty' feeling cars (JCW Mini, Civic on coilovers etc) struggle for grip as soon as the surface isn't perfect and New Zealand roads need club rally type setups
I had a 2014 Toyota Prius and adding the TRD rear sway bar was a game changer. The car felt so much less floaty when changing lanes around the speed limit. It took corners surprisingly well!
Yep, been doing that for a while. Got my last one to understeer with throttle input, and oversteer without. it could be balanced with just a little gas.
call me crazy but im running a 93 subaru legacy (inside a 1980 BRAT chassis) with no swaybars front or rear and it handles really well with surprisingly little body roll. they did not come with rear swaybars from the factory and are known to understeer so i figured it wouldnt hurt to test drive it without the front one installed and sure enough it makes a ton of mechanical grip! so heres a question: do different suspension setups cause more or less body roll? like is macpherson going to resist roll more than a solid axle for example? or am i only getting away with this cause my cg is super low?
I was driving on ice tracks last winter. Got annoyed by the tremendous oversteer my E30 318is offered. Removed link from the rear sway bar and car immediately felt faster. Thinking about improving front tire contact patch later. Previous owner has increased caster, which means that the front wheels tilt heavily with greater steering angles and in the slow sharp turns the car understeered before and still does, by a lot. Of course the limited slip in the back is probably also to blame, but compared to my brothers E36, my car is a lot slower in the sharpies and we used the same tyres. It's nice to see that car videos are not all about wide wheels, turbos and lowering, someone actually speaks about making cars better. Thanks for giving the insight. Greatly appreciated.
@@JulianEdgar in most cases, I would agree. But my theory is that on flat ice with streetlegal studs and almost no body roll in slow sharp turns, any camber over stock most likely worsens contact patch or pressure on the studs. I can even see on the trackday photos how unevenly loaded the front tyres were in the tight corners. Having tried similar cars which did not understeer as much, I'm fairly sure that extra caster is the problem.
@@JulianEdgar Increased -ve camber on the inside tire will decrease it's grip (as the camber is actually +ve as far as the tire is concerned) which could come into play at low-speed, low-G pivoting kind of motions like hairpins or an ice track. E30 has quite high caster, so it could be a real factor. Camber will also make longitudinal grip worse, which will just exaggerate the issues if braking is applied.
I too have an e30 but with the e36 328i engine and 3.46 plate lsd. The standard sport dampers, very slightly lowered springs, increased front caster with ever so slight toe out made my car very quick on our rough roads. Sometimes literally driving around other cars that had too low and stiff suspension. My one issue was low to mid speed corner exit oversteer. I thought it might be a combination of too much torque and relative light weight but now I'm thinking about trying to tweak the balance via the anti roll bars... Thank you for sharing your knowledge and experience everyone 🙏
I wonder how far sway bar links can go before they become unbearable on the roads. By that i mean if i were to use a rotating spring steel blade link rather than the traditional ball joint ones.
This is a very easy to understand yet highly educational video, I’ve known how a stiffer rear sway bar can be beneficial for fwd cars for more rear rotation but never knew the true reasoning behind this. Thank you for making this, you’ve gained a sub 😁
Hello! It’s amazing that this video was posted right before my experiment with sway bars! Thank you for sharing such a key point information! I’m was about to try solid sway bars instead of tubular on my Audi A3. It’s tuned from the factory to understeer 22.5x3.5 front and 20.7x2.8. I’ve found that vw sharan has 24mm solid front and 20mm solid rear. Passat r36 has 23.6 solid front and 21.7x3.6. Golf VI R 4wd 22 solid front 21.7x3.6 rear Sirocco R FWD 23.6x3.5 front 21.7x 3.6 rear Is there much difference between solid and tubular in terms of torsional resistance? What set up would you try? Thank you so much for your time and help! P.S. Can’t wait to get the new book!
Since it’s a popular platform for projects so I’ll share some information on the topic: standard Golf/TDI/A3: 21.7x3.0 or 22.5x.3.5 / 18.5x2.5 or 19.6x2.6 or 20.7x2.8 Scirocco: 21.7x3.0 or 22.5x.3.5 / 20.7x2.8 or 21.7x3.0 TT-RS quattro: 22 mm solid / 18.5 x 2.5 mm A3 Ambition/S-Line: 22,5 x 3,5 / 20,7 x 2,8 (FWD) Golf V GTI: 23,6 x 3,5 / 21,7 x 3,0 Golf V R32: 22,0 solid / 21,7 x 3,0 (4-motion) Golf VI GTI: 23,6 x 3,5 / 21,7 x 3,0 PR-0BF or 21,7 x 3,6 PR-0BM (DCC?) Golf VI R: 22,0 solid / 21,7 x 3,6 (4-motion) Scirocco R: 23,6 x 3,5 / 21,7 x 3,6 Touran 170 PS: 23,0 solid / 21,7 x 3,0 Passat R36: 23,6 solid / 21,7 x 3,6 (4-motion) Sharan 2011 on: 24.0 mm solid / 20.0 mm solid after market (almost all are solid): H&R TT Quattro: 24 / 22 mm incl. TT-RS H&R 'small': 26 / 22 mm Eibach AntiRoll: 26 / 23 mm KW clubsport: 26 / 23 mm (made by Eibach) VW Racing: 26 / 23 mm (made by Eibach, discontinued) ECS: 26 / 23 mm H&R 'big': 28 / 24 mm (AWE used to sell also a H&R 28 mm rear bar) H&R 4-motion/Quattro: 24 / 26 mm 034Motorsport: 25.4 mm rear only Autotech: 25 / 25 mm (tube/hollow; reliability issues) Whiteline: 24 / 24 mm (3-way adjustable) Neuspeed: 25 / 25 mm (tube/hollow; also 28 mm rear avail.; reliability issues) BFI/Stabila: -- / 25 mm rear only (different version for FWD and AWD) Hotchkis: 27 / 27 mm (tube/hollow) APR: 27 / 27 mm (tube/hollow; made by Hotchkis) BSH: -- / 27 mm (3-way) rear only
The stiffness difference between hollow and solid isn't as much as you might think. I'd go for a tubular rear bar that is a bit bigger in diameter than the existing one. 21.7 x 3.0 or 3.6?
@@JulianEdgar I'd disagree. This depends on the wall thickness and overall specifications of the bar. Some racing bars, if made solid, would produce wheelrates 100,000 N/m~ higher and this is AFTER installation stiffness, motion ratio and all that. A more accurate way to present it is that "The stiffness difference between OEM solid and hollow bars isn't as much as you might think". Usually the higher OD more sporty hollow bars will still be stiffer than the lower OD less sporty solid bar. Sometimes a higher OD solid bar might even be softer, if the torsion bar arm is very long, due to for example being a modification for an AWD version of the platform and so on. You need to do the math.
Hi Julian, also Julian here. What do you think about the idea of removing the front sway bar for improved performance? I race my car (2012 VW Golf R AWD) and did this with the advice of my mechanic who has many years experience racing FWD VWs and hes built some very fast race cars for himself. I found that it did improve the front grip however it did become a bit "numb" feeling and was susceptible lift off over steer and sometimes unpredictable over steer mid to corner exit. Should i re install the front sway bar and put a stiffer one in the rear? Are further underlying issues with completely removing a sway bar? Ive also heard of drifters doing this to their front sway bars too. Is there a way to change the balance predictably or is it just trial and error with the diameter of the bar and also the end link mount location?
Okay, so I have a 2016 Ford Focus SE hatchback (as you can see in my profile picture). I noticed recently that my car has started to have more body roll (not too much, but just enough to be annoying) when making turns, and I also noticed that the rear feels much looser than the front when I travel down a gravel/dirt road at around 50 MPH. Are those important clues that I should change my rear sway bar and links with high quality, aftermarket replacements, or could it be something else?
One thing unmentioned is that sway bars also add to the spring rate somewhat, or whatever it does to make the car more bumpy on poorly maintained roads. I've installed sway bars on my F10 BMW and the performance difference is amazing. You know what else is amazing? I'm now able to feel every change in the road including a small pebble. Trade-offs obviously, but i'm not going back to stock and I'm keeping both. I'm coming from a subaru which feels neutral in corners. So the bmw initially had an oversteery feeling and upgrading both gave me the balance I needed.
Quick question: Will a stiffer rear sway bar help drifting a open diff RWD? Cus im kinda thinking it would have a tougher time sliding, since the "open diff/stiff rear swaybar" setup, lets the lifted wheel spin even more, but idk. Any help much appreciated🙏
what people think when they see a racecar with most of the original suspension rebuilt/swapped/upgraded, they immediately assume this has to be the best and only way to make ANY car “good”. they often forget that in motor sport uses (any kind for that matter) these cars are purpose builtfor said uses. for daily driving/street uses changing one or two things (suspension-wise) is most of the time something more worthwhile and more effective than completely reworking the entire suspension. since your “dailies” come from the factory pre-set for road applications, there’s no real need for a complete overhaul, really. sure there are some flaws here and there, and some cars are made to be less about “spirited driving” than others, sure. but overall there’s nothing a simple mod or two such as a new/better swaybar (for example) would/could not fix.
Yes, if the suspension system is in good condition - eg dampers (shocks) and bushes. (I thought that obvious but seeing what some people have written I guess it needs to be stated.)
Would moving to softer sway bars (front and back) improve ride quality? It would be a relatively easy way to improve ride quality. Or even deleting them entirely, but not sure if it would be safe even if you drove gently.
How much of an affect would a sway bar have compared to a strut tower brace? One obvious disadvantage I can see is a strut tower brace can only be fitted to the front generally speaking. Just wondering if you've experimented with strut tower braces as well.
awesome video as usual! any chance you can do a similar one on Strut-Bars? They were all the rage when I was modding cars 20ish years ago, but I could never get a straight answer on what they were actually achieving (further than looking hot when you open the bonnet)
I have a bmw e46 so it’s front engine rwd that I take to the canyon it’s on stock suspension cuz I don’t want to dump a bunch of money in it yet but want it a little stiffer. It’s stock handling is already great it rarely oversteers or understeers in this case for just making less body roll should I just get a stiff front sway bar?
You could upgrade both bars by the same stiffness amount. Or fit stiffer springs and shocks, again increasing stiffness by the same amount front and back.
@Julian Edgar, what will be the title of your book? I would like to buy it. As an electrical engineer who loves cars. This is not something i learn in school or a work profession i can get into and learn. Do you also explain the sway bar concept for either a fwd or rwd car?
The book will be called: 'Vehicle Ride and Handling - Testing, Modification & Development'. Sway bars are covered, and FWD and RWD cars are covered in specific chapters.
Julian I am confused because you recognize that a stiffer sway bar results in a net reduction of grip when cornering for the side of the car with stiffer sway bar. So would adding a stiffer sway bar aways result in less grip, and therefore a less capable car? Would the ideal be to always install a softer sway bar on the side of the car you want to change the characteristics of? I have a front wheel drive car that understeers, so my understanding is compared to stock if I add a stiffer rear sway bar I will have less total grip at the rear but better balance, but if I add a softer front sway bar I will have more total grip at the front end and better balance which is ideal. Pleas let me know your thoughts, Thank you
For a 10 min video I deliberately simplified how sway bars work. They also add grip at the other end by causing a diagonal weight transfer. If you have a typical fwd, stiffen the rear sway bar.
So if understeer is the worst and you want your car either balanced or a bit oversteering...why have two sway bars at all? Seems like most cars should only have one sway bar, and mostly rear ones.
Because you also do need to limit body roll, as it results in camber loss of the outside tyres, reducing grip. However, many cars these days go too far in that respect.
I would argue the best thing for fixing understeer, would be camber. Going from stock to 3 degrees of camber up front will make a much bigger difference than altering the sway bar. Also, it depends on the car/package it comes with, but generally wider wheels/tires and camber should be the first mod someone does (in my opinion for track pace).
Only if you also want poorer braking, poorer traction (in a FWD) and greater inside tyre wear (road car). None of which occur with changing lateral weight transfer via sway bars!
@@JulianEdgar the amount of time lost in braking is massively trumped by increased cornering speed… but yes in a fwd you would compromise traction due to reduced contact patch when unloaded. However, running more camber allows you to have higher minimum corner speed and no one is getting back on throttle when the steering is straight. Your outside wheel will be loaded so id still think you’d have more traction on a track. Personally, I don’t have much fwd track experience, but the few people that run fwd track cars here all run -3+ degrees up front on track. Also, sure you’ll wear the inside a little more, but the comparison on track isn’t even close.
Not sure why you assume everything is about the track. About 1:1000 the number of people who track their cars versus drive on the street and want a good handling car. Running increased neg front camber will increase front cornering grip, but why not actually make use of the grip that all four tyres *already have available*? That is the point of the video, after all.
So I have a 1st gen Celica and it doesn't have a rear sway bar. There's a kit to get a rear sway bar installed on the live rear axel, is that going to serve the same effect as stiffening a rear sway bar?
Hi Julian, this is the first video I’ve come across of yours and it’s very informative just the type of channel I’ve been looking for. I’ve got a fwd car which I’ve had under steer issues with. I fitted a rear sway bar and am still having issues. Would completely removing my front sway bar be of any benefit? Thanks
That's usually a bit of a radical move, but you could do so for some careful testing (assuming that the sway bar doesn't help locate the wheels, of course).
@@JulianEdgar I may try see if the base model of my vehicle has a thinner sway bar in the front and try that first. Very much enjoyed the video mate I’ll be watching from now on.
@@timtrial3971 Ive done that before, funnily enough that's how I wrote off my 97 Camry. It was fun while it lasted and atleast no one died, pretty bad crash though
@herniagaming I only lfb in hillclimbs and rally sprints. You don't need to on downhill. I rarely get to do it. My truck has the steering column in way
Back in the day, it took me a long time to understand why sway bars change the car's balance because I couldn't find a clear explanation at the physics level. You've nailed the simple but correct way to explain it!
Oright, I think I understand. It will apply to people that have an issue with the way a car is driving, which I had a slight complain with my Honda back in the day where in original form it was way too tail happy, after I fitted my coilovers it drove way better and much more predictable but now it had a little bit too much understeer sometimes, nothing that I couldn't control but it sometimes was a little issue. I was messing with coilover dampening in front to counter it, but never felt any massive difference. Sway bar was on my list as many used to says it makes the car drive even better, but no one ever really went deeper into why that's the case. I have a brief knowledge on car suspension but far from expert. Now this helps a lot. My MX5 currently has the same issue on stock suspension, front will start understeering, with it it's a little different tho cuz often it will oversteer after correcting it, makes it fun, but it's an odd behaviour. Obviously it's an old ass car with 20yr old bushes and so on, but worth knowing this for the future, especially when I'll be setting up my 370Z. Thankfully that doesn't have any of these issues, it grips hard and is definitely a little more on the oversteer side, but very controlable and pretty predictable. Again that's on stock suspension, and I don't push it that hard so I didn't run into limits of the oem setup, I do want stiffer setup tho, purely for the driver feel, also to reduce the body roll as it's a little more than I would like. I would love to see next video on stuff like suspension dampening and spring rates in greater detail, I may even get your book, or an audio book if that will be available!
I think the purposely made some SUV understeer is that it prevent user error that result in the car rolling over resulting in accidents for average everyday driver.
@@JulianEdgar yes that is true because the correction for understeer is using the brakes which is easy to do for every day driver. I can imagine oversteering a SUV can resilt in rolling the car. Thanks for the video i enjoy them even as a motorcycle fabricator.
Great informative video 👍 To somewhat bolster your explanation, but also contradict the point about kits, is that kits I’ve seen seem to significantly increase the size of one bar over the other with aim (I assume) of the manufacturer to restore the balance and reduce undesirable driving characteristics. Assuming the manufacturers actually R&D their products, surely when sold as a set, it’s in their interest to deliver a neutral/balanced feel, unless of course they’re relying on uneducated/inexperienced customers. Again, great explanation and not disagreeing with your overall message 🙂
@@JulianEdgar How do you know this tho apart from feeling it? "Oh this is quite stiff in roll" is quite subjective, do you have something objective to help understand the issue at hand?
[Shrug] Both are quantifiable if you wish to go to the trouble. Eg Measure RMS roll accelerations over one-wheel bumps, and compare circular skid pan times with and without rain with varying degrees of roll stiffness. Anyone can make things more complicated than necessary!
Yes this man knows what he is talking about. Followed his suggestion on a Volvo xc70 witch is very soft and has a lot of understeer from the factory. Replaced rear from 20 to 25mm and also replaced front from 24 to 26mm. Amazing difference. Of course loosing a bit traction in off-road and full out suspension travel limit, but not hardly any noticeable compared to gained feel of handling ferormance👍
@@LateralTwitlerLT Well yes, but why was there the need to upgrade the front swaybar then? Perhaps he felt the car was rolling too much as well? If he ONLY wanted to reduce the understeered then there'd be no need to upgrade the front also. Was just gonna ask him about it.
A rear sway bar was my first modification to my car, it sharpened the handling on my FWD car in a lovely way. After that every other suspension and wheel change just compounded the sharpness in a complimentary way. Best value/dollar modification that is noticeable right away in my opinion.
My car is plowing straight in winter. It's really annoying me, sometimes I even handbake a bit to help it turn. I thought that I can fit a thicker rear sway bar from different trim, but this is already the thickest there was. But I never thought about going softer in front, because I hate body roll. There were some thinner ones on this model. After this video, I am thinking maybe I will also give it a go with the softer front. Maybe i will like it.
I have a 2013 Audi s4, and like most audis they tend to understeer because of the engine being so far forward. By far the best upgrade ive done was a larger rear sway bar, and it will even get a little sideways now if i push it hard enough.
Thank you for the wonderful and concise video. I can only speak from off-road community, but this kind of clears up why disconnecting front sway bar can improve cross axle articulation, more effective than removing both sway bars. I also read above in comments that a pair of stiffer rear coils achieve similar effect to a stiffer rear sway bar, but can it potentially improve cross-axle articulation, on 5 link solid rear axle vehicle? If you draw a simple diagram, coil springs on a 5 link solid rear axle are also pushing down opposite wheel as the fulcrum is the other wheel.
I never knew-probably due to inexperience-exactly why many road cars have both front and rear sway bars if having only one could compensate for the steering imbalance after designing in flat-ride spring rates. The drawback of having a sway bar is that the left and right sides become coupled, reducing grip on one-wheel bump scenarios. One thought is that having both sway bars might be necessary because designing the control arm nodes to have enough camber gain and enough travel while hitting ride frequency requirements could be challenging, so the easy way out would be to add roll stiffness by putting stiff sway bars. Another idea is that higher roll stiffness feels more responsive; thus, it appeals to younger folks.
Thank you sir! This was very helpful! What if the car has 50/50 power distribution? (2022 WRX) Also, is a stiffer sway bar makes the ride quality worse? The car is already very stiff.
@JulianEdgar would a front strut tower brace have the same effect as a front sway bar, ie increasing under steer when installed in isolation? Considering installing on my 2016 BMW 428i and have read reviews that people feel it on turn responsiveness but not necessarily handling balance
Sway bars almost seem too easy, but when you experience the before and after, it seems ridiculous not to do it first. Great explanation! Interested in buying your book:)
Amazing advice more people need to hear. It's almost better to be modifying on a budget at first, as you look to really effective solutions like sway bars before someone can sell you a set of expensive coilovers or suspension 'stage' tuning kits that make any modern car far too stiff,, too low, and disconnected from the road.
Stiffer usually means fatter, but it could also mean changing the lever arm length, or (to a lesser degree) changing the sway bar bushes to firmer ones.
Like Julian said, changing the bushings will change the wheelrate, but not very much. Bushings are components in installation stiffness, which is a second spring that works in series with your suspension spring. Making that second spring stiffer will mean you have more rate "left over" and less of it is "lost". This of course will come at the expense of more wear on the mount that the bushing is attached to; solid metal ones might snap the mounts off. Bushings, even rubber ones, are very stiff, but the wheel assembly is typically stiffer, so it's a bit effective to increase the rate of the bushings for higher IK (installation stiffness). The catch is that how much IK affects your wheelrate depends on the input rate of the spring itself. Very soft roadcar bars might only lose let's say 2% of rate between OEM bushings and metal ones, while stiffer racing ones might lose 20% and so on. What stiffer bushings WILL do is generally decrease slack in the system, which reduces the size of the "dead zone" where the bar isn't activated but the wheels have deflected.
Thank you for making this video. I read stuff about the rear sway bar, and this clears things up even more. Just one question. Is there a huge difference between a rear sway bar and a front strut bar? Thanks.
A rear stabilizer and a front strut bar don't perform the same function and are incomparable entirely. One is a spring, the other is an elastokinematic component.
Lovely video, I intend on getting into motor racing be it time attack or wheel to wheel in IPRA or similar, these videos are amazing to watch. Thank you for the time you take to educate.
I think there needs to be a follow up on how stiff suspension interacts with stiff or soft. Such as what happens if you have radically soft suspension on stiff anti sway bars.
On dirt track cars, some people on a tight budget outright remove the front sway bar to get more over steer. They handle like crap but it does seem to work
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This is something I’ve tried to tell people for years. Easily one of the best bang for buck modifications you can make to your car. Every time I modify a car, one of my first purchases is an upgraded rear anti-roll bar.
Yes, me too. Even before I change tyres...
It's good for smooth roads... It makes the ride much rougher on bad roads though. The double edged sword of stiffness.
It does take away some comfort. Depending on where you live, If comfort is the priority, don't do it.
Otherwise it definitely helps in cornering handling and stability
I don't think you watched the full video?
@@JulianEdgar no way 😳. Thx again. 🙏 I hope there is a German translation of ur book.
I thought that was common sense, it’s pretty well known in 4x4 when you raise the car more than 3 inches to not just lose all steering or rolling over in the first sharp turn
Funny story, this trick is how I used to beat the pants off of people in the old video game Gran Tourismo.
It was billed as a "driving simulator" and bragged about a realistic physics engine. That's what got me interested in it, and I wasn't disappointed.
In that old game, sway bars and lightening were the under appreciated modifications that could turn a boring compact into a consistent winner.
My general tactic for cheapest results was to fit the "racing" level bars, both front and rear. These offered the greatest adjustment range, and I'd start with the front on full soft, and the rear midway. I'd consistently beat far more powerful cars with little effort. It would rotate very fast in low speed turns, fairly neutral in faster turns, and allowed full power on corner exits a lot earlier than my overpowered, understeering, rear drive competitors.
Works in real life too.
Gran Turismo series still going strong at its 7th release
babe wake up julian egdar just posted a new video
But what did 'babe' say?
@@JulianEdgar she asked if it was an aerodynamic testing video and she went back to sleep due to the resulting answer😔
The ND Mazda MX-5 might be one of the exceptions among modern performance cars, very soft suspension setup and pretty good handling balance from the factory.
It's a well-designed car - there's no issue with soft suspension giving good handling.
It also benefits from 50-50 weight distribution and very low overall weight :)
I would guess these factors allow it to have a soft suspension and maintain good dynamics
It's amazing how many people do not understand this. Thanks for making this video. And hopefully some of the internet "experts" will watch this.
This is what I come to TH-cam for
It's even better than that! It's true that the sway bar increases outer wheel load on the axle it's mounted at, reducing that axle's cornering grip.
Additionally, it also increases wheel load on the diagonally opposed wheel on the other axle, as long as the body is stiff enough.
So you are not just making one axle worse, you are making the other better!
Good video! I'd love to hear your thoughts on horizontally mounted chassis dampers like the SARD motion control beam.
Yes in my upcoming book I cover how swaybars work in much more detail, including the diagonal weight transfer.
@@JulianEdgar When do you think that will be published? :)
It's largely finished - just waiting on final materials and feedback from expert reviewers. But that takes time - perhaps 3 months?
@@JulianEdgar thanks for the reply!
@@JulianEdgar Good video. I'm looking forward to the book. Cheers for all of your Autospeed content too - great stuff.
Saw the thumbnail and knew I would like the presentation
As the wise man once said: "even the worst suspension can be improved by preventing it from operating." Mostly necessary due to roll center and how high cars are. If you have a low car, or one with low center of gravity (EV?) may not be necessary? As the owner of a string of VW cars I always found it hilarious I was undoing the semi-independent trailing arm rear suspension. It's also neat when the torsion beam can house a splined torsion bar of varying specifications, without needing any linkages.
Idk what those words mean but I’m assuming you took the springs out and are just letting control arms and body flex be your suspension
Hahaha that quote is great.
This is the exact problem I'm fighting, and while I found the answer myself through hours of research I'm glad to have the confidence of this video backing it.
Any good references you’ve found in your research?
I have a Pontiac Grand Prix. The suspension is exactly like a 68-72 GM A-Body (Chevelle, GTO, 442, GS). I did the poly bushings, cut one full coil from the front coils, added a 1" rear bar and gas shocks. The MOST PROFOUND result was replacing the stock 1" front bar with a 1-1/4 bar from a WS-6 Trans Am. The car rides firm but not harsh. However, it corners very well. It is fun to drive in twisty roads. The last change I need to make is to install a bump steer correction kit.
Julian, great to see you posting again.
I really respect your advice.
Fitting a stiffer sway bar at the rear on my normal cars has always made them just 2x more enjoyable to drive. They are boring cars by default, but this has always been the minimum for what I would change to my FWD super understeery cars.
Excellent presentation, sir. To your point, I have posted the fastest time at many SCCA autocross events over the past 14 seasons while running either an NB Miata with no rear sway bar, or a Subaru WRX with no front sway bar.
I actually won the D Street class regionals in my 2017 WRX with no front sway bar and bone stock springs/ dampers. I only tuned the car balance with alignment, tire pressure, my right foot, and lots of second-hand knowledge from books about Autocross suspension theory (Dan Watson is one of my favs).
After looking through your videos tonight, I’m looking certainly forward to adding your book to my collection next.
When VW worked to set their Nurburgring lap times for the MK2 Golf It was faster around the track with no front sway bar. The rear doesn't run a separate sway bar but the rear axle itself is effectively one.
I've been trying to improve handling on my VB WRX for autocross.
Sway bars are good and easy modifications, just be careful. On one of my cars I went from a hollow 19 to a hollow 25mm in the rear (from the sportier trim level of the car) and it snapped the mounting point off the subframe after some excited driving. After re welding it stronger its snapped in new places about 5 more times and now I have to drop the subrame and reinforce everything for it lol. but if you have a car that isnt made of cheese it shouldnt be an issue
Yes you do see and read the fact that more unequally balanced left to right tires have less maximum grip potential, compared to more equally loaded tires. That’s what it’s all about!
Bought 2 of your books: One on aerodynamics and the other on argumentation & logical persuasion.
Good stuff. I know you're not a fan of F1 and motor racing, but I forgive you 😉
Yep. I live in Brazil and we don't have easy access to performance stuff, everything is either too expensive or or outright impossible to find.
I did the sway bar first in my Fiat Uno. The Uno is the first global car Fiat has ever made, released back in 1983. Here in Brazil it was sold from 1984 to 2013, only stopping production cuz airbags and ABS became mandatory in 2014 up cars.
From 1997 and above the Uno became the cheapest car one coumd buy, lacked any luxury or performance.
But up to 1996 there were fancier models and even sportive models like the Uno Turbo, one of the coolest hot hatches you could get in Brazil and Europe in the early 90s.
Mine is a 2001 model, so a cheap, boring, economic car.
That until I bought the sway bar from a Uno Turbo and installed in mine, it instantly begun handling like a kart lol. Since then I've given it a bigger engine, gigantic brakes and excelent tires, Recaro seats and so on. (It's way better than a Uno Turbo now)
But yeah, the best bang for buck upgrade was the sway bar. Truly night and day difference!
Since then I've upgraded my brother's mk4 Golf with sway bars from the R32 lol.
And also my parent's very boring, very mundane Logan (sold here as a Renault, but actually a Dacia elsewhere).
Here in Brazil they made a hot hatch version of the Sandero, simply called Sandero R.S. Actually tuned by the french Renault R.S division, it had beter brakes, insane tires, completely overhauled suspension, etc.
Since the Logan is just a sedan version of the Sandero, I purchased the sway bar from the Sandero R.S and installed it in the Logan.
Easily the best thing I ever did, it used to roll so much it was scary taking the highway with it. Now it stays put and I've chasen much better, much stronger cars around the mountain roads we have here. Hahaha
I've wondering to make my own rear swaybar for my mazda 2, but I don't know how to calculate what stiffness I need. I can just copy the design of a manufacturer, but as a junior engineer I'm more interested in how to design a proper anti roll bar. Also I find that my car has pretty neutral handling so I don't want to ruin it putting a stiff sway bar at the back.
You will find popery designing a rear sway bar to be immensely difficult. eg you will need C of G height, suspension roll centre heights, stiffness of springs, motion ratios of both the springs and proposed bar, etc. Better to copy a similar car as a starting point.
it's very hard (pun intended) to really overdo it, but maybe with a rear torsion beam you won't need as much. take measurements of the existin setup and calculate what you need to double the stiffness. I went with 4x stiffer myself
Nice good commonsense approach to car suspension mods
It was great info. Clear and concise as always. Good reassurance because I was building on information from racing sims up until this point and was not 100% sure this change is a great idea for the road.
Anyways I have a Suzuki Swift/Cultus hatchback from 1997 which has quite noticable understeer in roundabouts even at normal speeds. These 1.0l models were not fitted with any sway bars and only the saloons and gti-s have one at the rear. So I sourced one from a saloon but had to realize the mounting points are not present on the underbody of the hatchback. At least now I go into the welding phase more confidently that it will have the desired effect and the modification will not have to be reverted.
I dont think what youre experiencing is understeer but... if you really want it then change the sway bar. Youre certainly not going to make it any worse thats for sure :D
Extremely nice video. I am building a drift E30 and i have fitted a rear sway bar (stock) because it wasn't choosed on the initial car. I have also fitted an inline 6 engine instead of the inline 4 it had and not changed anything about the front sway bar yet. I will try driving the car without sway bar in the rear as in drifting you want all the available traction on the rear. Thanks for your nice videos. Greetings from Greece!
Too powerful, I’ve learned it through Forza Motorsports 7 and since then I am trying to tell people but it is soo underrated!
There is another use for sway bars in handling too. Helping with reversing a turn.
From my own experimentation, mostly in computer simulations, I totally agree. When I'm tuning a car, and dialing in the handling, usually I adjust only one end at a time unless both ends are radically off from what they should be.
While I tend to like running the softest suspension and sway bars that will allow good handling, I have noticed that having less roll stiffness tends to have a negative impact on the balance of a car when transitioning right from a turn in one direction to a turn in the other direction. For relatively smooth race tracks that have tight windy bits with no strait in between turns of opposing directions, I tend to retune the balance with stiffer sway bars. I adjust them both stiffer together in order to maintain the balance of the car while reducing the time it takes for the car to settle out of the corner. This can, as pointed out in the video, make the car more skatey throughout most of the track, but if you offset the minimal time lost through simple turns by dramatically improving the time through a technical bit, it can be worth it. But again, as soft as you can go while getting the job done.
If anyone wants to weigh in with something to expound on this, please feel free. This is just from my experience learning to tune in simulators like LFS(Live For Speed) which provides great freedom to experiment with the suspension. I find that what Julian Edgar said in the video to be true, and it fits my experience as stated above.
Thank you for saying this. This rings very true for us in the bmw community - i see alot of people putting very stiff springs on their car. These aftermarket coilovers:
ruin ride quality
compromise chassis in suspension mounting points (in particular this exacerbates issues on e46 and e36 3er chassis)
sometimes cost far more than oe options
provide minimal handling improvements over factory sport suspension options.
But when you bring up that an upgraded antiroll bar will make a bigger difference you are shut down and told you dont have an understanding and that the coilovers are "worth it" - I dont know what is causing this, potentially marketing by coilover manufacturers.
The other belief is that lower = better handling. It just doesn't but that's another issues.
Yes, coilovers are just the current fashion. I don't know why.
@@JulianEdgar very glad i found your channel. i plan to purchase some of your books and watch the rest of your content.
I think the lower is better thing comes from modern race cars producing more downforce the closer they are to the floor, which obviously doesn't matter even slightly in a normal car context.
I think many people want coilovers because the ride height is adjustable to their aesthetic preferences. It's less about the performance improvement, and more about replacing old stuff with new and making the car look better. If you have a beat-up old E36, a cheap set of coilovers will still be an improvement from stock 30-year-old blown out shocks and springs. Personally, I would rather keep it simple with new shocks and lowering springs, but I understand the appeal.
Have done a bit of experimenting with the Chevy Cruze and autocross racing. Car started racing on stock suspension, then eibach lowering springs, then bolted a stiffening element to the rear twist beam, then got Koni yellow shocks for the rear, then got rear spring stuffers (rubber between coils) and finally the car began to rotate in the turns with 8 psi higher rear tire pressures vs front. This became my daily driver setup when not racing.
The next incremental improvement [for autocross times] are the stiff spring option ISC coilovers, with 12k front and 10k rear springs, rear motion ratio 0.66. It rides terrible and gets into a harmonic on some roads while traveling at freeway speeds which bucks me like a bull ride. The car more easily rotates on the race track with less difference in rear vs. front tire pressure and less body roll.
This season has more mods. I ran the calcs and got a set of 6.7k front springs to mate with the 10k rear springs giving a calculated frequencies of 1.9 front and 2.1 rear to try and achieve flat ride. The front shocks will be replaced with the standard ISC valving. Because of the soft front springs, I opted to get both the front and rear [adjustable] sway bars, front bar logic is to reduce body roll from the softer springs.
Great video! I have a question about this topic, I have a bmw e82 135i, which has very little (and not adjustable) camber at the front wheels and zero camber gain, putting the tires in a disadvantageous position when cornering hard, basically loading only the outside of the tire (which wears much faster than the outside).
Some people in the forums suggest that fitting a stiffer front sway bar the reduction in body roll allows the tires to have better contact on the ground thus enabling them to produce more grip than with a softer bar.
Do you think this could be the truth?
Yes, the only real reason to limit body roll is to reduce camber loss on the outside wheel.
Cannot be explained better. So clear.
A pleasure 😊
I'll watch again ❤
Agreed no front bar. I race a Mazda3 in SCCA ITA class. My car turns best with no front bar and a big bar in the rear.
Not sure I ever recommended that. On a street car, you'd need to be quite careful in taking that approach.
I should note that i like a very loose feel and trust my LSD to pull me out of a slide.
My car has 50:50 weight distribution and handle very neutral 😂 From this video I should do nothing. The only thing I can do to increase grip is better tires... I already have SportMaxxRT2😂
Legit the best video about swaybars. Not hard when most are just "fit my sponsors product" but you deliver again.
I have applied a bunch of things you cover and friends with more 'sporty' feeling cars (JCW Mini, Civic on coilovers etc) struggle for grip as soon as the surface isn't perfect and New Zealand roads need club rally type setups
I had a 2014 Toyota Prius and adding the TRD rear sway bar was a game changer. The car felt so much less floaty when changing lanes around the speed limit. It took corners surprisingly well!
Yep, been doing that for a while. Got my last one to understeer with throttle input, and oversteer without. it could be balanced with just a little gas.
call me crazy but im running a 93 subaru legacy (inside a 1980 BRAT chassis) with no swaybars front or rear and it handles really well with surprisingly little body roll. they did not come with rear swaybars from the factory and are known to understeer so i figured it wouldnt hurt to test drive it without the front one installed and sure enough it makes a ton of mechanical grip! so heres a question: do different suspension setups cause more or less body roll? like is macpherson going to resist roll more than a solid axle for example? or am i only getting away with this cause my cg is super low?
10:38 Unless you have Peugeot 206 where the rear axle is basically made out of 1 sway bar and 2 half sway bars.
Its call a "Anti-Sway" bar or a Stabilizer bar or a Anti-roll bar.
I was driving on ice tracks last winter. Got annoyed by the tremendous oversteer my E30 318is offered. Removed link from the rear sway bar and car immediately felt faster.
Thinking about improving front tire contact patch later. Previous owner has increased caster, which means that the front wheels tilt heavily with greater steering angles and in the slow sharp turns the car understeered before and still does, by a lot. Of course the limited slip in the back is probably also to blame, but compared to my brothers E36, my car is a lot slower in the sharpies and we used the same tyres.
It's nice to see that car videos are not all about wide wheels, turbos and lowering, someone actually speaks about making cars better.
Thanks for giving the insight. Greatly appreciated.
Increased castor gives increased dynamic camber that should reduce understeer, not increase it.
@@JulianEdgar in most cases, I would agree. But my theory is that on flat ice with streetlegal studs and almost no body roll in slow sharp turns, any camber over stock most likely worsens contact patch or pressure on the studs. I can even see on the trackday photos how unevenly loaded the front tyres were in the tight corners. Having tried similar cars which did not understeer as much, I'm fairly sure that extra caster is the problem.
Yes that sounds right for a very low friction surface.
@@JulianEdgar Increased -ve camber on the inside tire will decrease it's grip (as the camber is actually +ve as far as the tire is concerned) which could come into play at low-speed, low-G pivoting kind of motions like hairpins or an ice track.
E30 has quite high caster, so it could be a real factor.
Camber will also make longitudinal grip worse, which will just exaggerate the issues if braking is applied.
I too have an e30 but with the e36 328i engine and 3.46 plate lsd.
The standard sport dampers, very slightly lowered springs, increased front caster with ever so slight toe out made my car very quick on our rough roads. Sometimes literally driving around other cars that had too low and stiff suspension.
My one issue was low to mid speed corner exit oversteer. I thought it might be a combination of too much torque and relative light weight but now I'm thinking about trying to tweak the balance via the anti roll bars...
Thank you for sharing your knowledge and experience everyone 🙏
I wonder how far sway bar links can go before they become unbearable on the roads.
By that i mean if i were to use a rotating spring steel blade link rather than the traditional ball joint ones.
This is a very easy to understand yet highly educational video, I’ve known how a stiffer rear sway bar can be beneficial for fwd cars for more rear rotation but never knew the true reasoning behind this. Thank you for making this, you’ve gained a sub 😁
But I'd have to drop my subframe or do some fabrication to replace mine, so no
Hello! It’s amazing that this video was posted right before my experiment with sway bars!
Thank you for sharing such a key point information!
I’m was about to try solid sway bars instead of tubular on my Audi A3. It’s tuned from the factory to understeer 22.5x3.5 front and 20.7x2.8. I’ve found that vw sharan has 24mm solid front and 20mm solid rear.
Passat r36 has 23.6 solid front and 21.7x3.6.
Golf VI R 4wd 22 solid front 21.7x3.6 rear
Sirocco R FWD 23.6x3.5 front 21.7x 3.6 rear
Is there much difference between solid and tubular in terms of torsional resistance? What set up would you try? Thank you so much for your time and help!
P.S. Can’t wait to get the new book!
Since it’s a popular platform for projects so I’ll share some information on the topic:
standard Golf/TDI/A3: 21.7x3.0 or 22.5x.3.5 / 18.5x2.5 or 19.6x2.6 or 20.7x2.8
Scirocco: 21.7x3.0 or 22.5x.3.5 / 20.7x2.8 or 21.7x3.0
TT-RS quattro: 22 mm solid / 18.5 x 2.5 mm
A3 Ambition/S-Line: 22,5 x 3,5 / 20,7 x 2,8 (FWD)
Golf V GTI: 23,6 x 3,5 / 21,7 x 3,0
Golf V R32: 22,0 solid / 21,7 x 3,0 (4-motion)
Golf VI GTI: 23,6 x 3,5 / 21,7 x 3,0 PR-0BF or 21,7 x 3,6 PR-0BM (DCC?)
Golf VI R: 22,0 solid / 21,7 x 3,6 (4-motion)
Scirocco R: 23,6 x 3,5 / 21,7 x 3,6
Touran 170 PS: 23,0 solid / 21,7 x 3,0
Passat R36: 23,6 solid / 21,7 x 3,6 (4-motion)
Sharan 2011 on: 24.0 mm solid / 20.0 mm solid
after market (almost all are solid):
H&R TT Quattro: 24 / 22 mm incl. TT-RS
H&R 'small': 26 / 22 mm
Eibach AntiRoll: 26 / 23 mm
KW clubsport: 26 / 23 mm (made by Eibach)
VW Racing: 26 / 23 mm (made by Eibach, discontinued)
ECS: 26 / 23 mm
H&R 'big': 28 / 24 mm (AWE used to sell also a H&R 28 mm rear bar)
H&R 4-motion/Quattro: 24 / 26 mm
034Motorsport: 25.4 mm rear only
Autotech: 25 / 25 mm (tube/hollow; reliability issues)
Whiteline: 24 / 24 mm (3-way adjustable)
Neuspeed: 25 / 25 mm (tube/hollow; also 28 mm rear avail.; reliability issues)
BFI/Stabila: -- / 25 mm rear only (different version for FWD and AWD)
Hotchkis: 27 / 27 mm (tube/hollow)
APR: 27 / 27 mm (tube/hollow; made by Hotchkis)
BSH: -- / 27 mm (3-way) rear only
The stiffness difference between hollow and solid isn't as much as you might think. I'd go for a tubular rear bar that is a bit bigger in diameter than the existing one. 21.7 x 3.0 or 3.6?
@@JulianEdgar I'd disagree. This depends on the wall thickness and overall specifications of the bar. Some racing bars, if made solid, would produce wheelrates 100,000 N/m~ higher and this is AFTER installation stiffness, motion ratio and all that.
A more accurate way to present it is that "The stiffness difference between OEM solid and hollow bars isn't as much as you might think".
Usually the higher OD more sporty hollow bars will still be stiffer than the lower OD less sporty solid bar. Sometimes a higher OD solid bar might even be softer, if the torsion bar arm is very long, due to for example being a modification for an AWD version of the platform and so on. You need to do the math.
My truck didn’t come with a rear sway bar, so I’m putting one in soon
Put a rear sway bar on my Toyota Tundra and it was a major improvement.
Hi Julian, also Julian here. What do you think about the idea of removing the front sway bar for improved performance? I race my car (2012 VW Golf R AWD) and did this with the advice of my mechanic who has many years experience racing FWD VWs and hes built some very fast race cars for himself. I found that it did improve the front grip however it did become a bit "numb" feeling and was susceptible lift off over steer and sometimes unpredictable over steer mid to corner exit. Should i re install the front sway bar and put a stiffer one in the rear? Are further underlying issues with completely removing a sway bar? Ive also heard of drifters doing this to their front sway bars too. Is there a way to change the balance predictably or is it just trial and error with the diameter of the bar and also the end link mount location?
Trial and error largely. And of course knowing the handling problems you're actually trying to fix.
What a breath of fresh air. Easy to understand and easy to do. Thank you.
Okay, so I have a 2016 Ford Focus SE hatchback (as you can see in my profile picture). I noticed recently that my car has started to have more body roll (not too much, but just enough to be annoying) when making turns, and I also noticed that the rear feels much looser than the front when I travel down a gravel/dirt road at around 50 MPH. Are those important clues that I should change my rear sway bar and links with high quality, aftermarket replacements, or could it be something else?
Most likely worn dampers / shock absorbers.
Based and zoompilled
Thanks Chad daddy
One thing unmentioned is that sway bars also add to the spring rate somewhat, or whatever it does to make the car more bumpy on poorly maintained roads. I've installed sway bars on my F10 BMW and the performance difference is amazing. You know what else is amazing? I'm now able to feel every change in the road including a small pebble. Trade-offs obviously, but i'm not going back to stock and I'm keeping both. I'm coming from a subaru which feels neutral in corners. So the bmw initially had an oversteery feeling and upgrading both gave me the balance I needed.
The increase in spring rate on one-wheel bumps from stiffer sway bars is heavily emphasised in my book.
Quick question:
Will a stiffer rear sway bar help drifting a open diff RWD?
Cus im kinda thinking it would have a tougher time sliding, since the "open diff/stiff rear swaybar" setup, lets the lifted wheel spin even more, but idk.
Any help much appreciated🙏
I know nothing about drifting, I am afraid.
what people think when they see a racecar with most of the original suspension rebuilt/swapped/upgraded, they immediately assume this has to be the best and only way to make ANY car “good”. they often forget that in motor sport uses (any kind for that matter) these cars are purpose builtfor said uses. for daily driving/street uses changing one or two things (suspension-wise) is most of the time something more worthwhile and more effective than completely reworking the entire suspension. since your “dailies” come from the factory pre-set for road applications, there’s no real need for a complete overhaul, really. sure there are some flaws here and there, and some cars are made to be less about “spirited driving” than others, sure. but overall there’s nothing a simple mod or two such as a new/better swaybar (for example) would/could not fix.
Yes, if the suspension system is in good condition - eg dampers (shocks) and bushes. (I thought that obvious but seeing what some people have written I guess it needs to be stated.)
What about cars that already have 50/50 weight distributions? Would a car like the Rx7 FD need front on rear sway bars?
You don't start with that. You start with the handling behaviour you're trying to improve.
Would moving to softer sway bars (front and back) improve ride quality? It would be a relatively easy way to improve ride quality. Or even deleting them entirely, but not sure if it would be safe even if you drove gently.
Yes, sort of. However, the chief determinants of ride quality and springs and dampers (shocks), and longitudinal compliance.
How much of an affect would a sway bar have compared to a strut tower brace? One obvious disadvantage I can see is a strut tower brace can only be fitted to the front generally speaking. Just wondering if you've experimented with strut tower braces as well.
Strut braces do basically zero on any modern car - at least when compared to sway bars.
awesome video as usual! any chance you can do a similar one on Strut-Bars? They were all the rage when I was modding cars 20ish years ago, but I could never get a straight answer on what they were actually achieving (further than looking hot when you open the bonnet)
Strut bars basically do little / nothing on any modern cars.
I have a bmw e46 so it’s front engine rwd that I take to the canyon it’s on stock suspension cuz I don’t want to dump a bunch of money in it yet but want it a little stiffer. It’s stock handling is already great it rarely oversteers or understeers in this case for just making less body roll should I just get a stiff front sway bar?
You could upgrade both bars by the same stiffness amount. Or fit stiffer springs and shocks, again increasing stiffness by the same amount front and back.
@Julian Edgar, what will be the title of your book? I would like to buy it. As an electrical engineer who loves cars. This is not something i learn in school or a work profession i can get into and learn. Do you also explain the sway bar concept for either a fwd or rwd car?
The book will be called: 'Vehicle Ride and Handling - Testing, Modification & Development'. Sway bars are covered, and FWD and RWD cars are covered in specific chapters.
Julian I am confused because you recognize that a stiffer sway bar results in a net reduction of grip when cornering for the side of the car with stiffer sway bar. So would adding a stiffer sway bar aways result in less grip, and therefore a less capable car? Would the ideal be to always install a softer sway bar on the side of the car you want to change the characteristics of? I have a front wheel drive car that understeers, so my understanding is compared to stock if I add a stiffer rear sway bar I will have less total grip at the rear but better balance, but if I add a softer front sway bar I will have more total grip at the front end and better balance which is ideal. Pleas let me know your thoughts, Thank you
For a 10 min video I deliberately simplified how sway bars work. They also add grip at the other end by causing a diagonal weight transfer. If you have a typical fwd, stiffen the rear sway bar.
So changing the sway bar linkage bushings is the second easiest way to improve handling?
No, I've always found this to be of only minor benefit - unless of course the originals are stuffed.
Thanks for sharing.
Where did you source the custom sway bar?
Signature Swaybars
@@JulianEdgar thanks
What about active sway bars, like in the Xantia Activa? That's probably one great technology not that much used....
Covered in my book on the history of suspension - www.amazon.com/Car-Suspension-over-years-handling/dp/B09CRNQB9P
How about strut bars? Similar effect? How do they differ from sway bars?
Strut bars do basically nothing on any modern car. Compared to sway bars, anyway.
Soooooo with this, Can you make a FWD feel more like a RWD with a stiffer front rear sway bar?
Not really sure what you mean. You can make a FWD oversteer, but when driving the car, you don't achieve it in the same way as making a RWD oversteer.
So if understeer is the worst and you want your car either balanced or a bit oversteering...why have two sway bars at all? Seems like most cars should only have one sway bar, and mostly rear ones.
Because you also do need to limit body roll, as it results in camber loss of the outside tyres, reducing grip. However, many cars these days go too far in that respect.
I would argue the best thing for fixing understeer, would be camber. Going from stock to 3 degrees of camber up front will make a much bigger difference than altering the sway bar.
Also, it depends on the car/package it comes with, but generally wider wheels/tires and camber should be the first mod someone does (in my opinion for track pace).
Only if you also want poorer braking, poorer traction (in a FWD) and greater inside tyre wear (road car). None of which occur with changing lateral weight transfer via sway bars!
@@JulianEdgar the amount of time lost in braking is massively trumped by increased cornering speed… but yes in a fwd you would compromise traction due to reduced contact patch when unloaded. However, running more camber allows you to have higher minimum corner speed and no one is getting back on throttle when the steering is straight. Your outside wheel will be loaded so id still think you’d have more traction on a track. Personally, I don’t have much fwd track experience, but the few people that run fwd track cars here all run -3+ degrees up front on track.
Also, sure you’ll wear the inside a little more, but the comparison on track isn’t even close.
Not sure why you assume everything is about the track. About 1:1000 the number of people who track their cars versus drive on the street and want a good handling car. Running increased neg front camber will increase front cornering grip, but why not actually make use of the grip that all four tyres *already have available*? That is the point of the video, after all.
So I have a 1st gen Celica and it doesn't have a rear sway bar. There's a kit to get a rear sway bar installed on the live rear axel, is that going to serve the same effect as stiffening a rear sway bar?
Yes
Hi Julian, this is the first video I’ve come across of yours and it’s very informative just the type of channel I’ve been looking for. I’ve got a fwd car which I’ve had under steer issues with. I fitted a rear sway bar and am still having issues. Would completely removing my front sway bar be of any benefit? Thanks
That's usually a bit of a radical move, but you could do so for some careful testing (assuming that the sway bar doesn't help locate the wheels, of course).
@@JulianEdgar I may try see if the base model of my vehicle has a thinner sway bar in the front and try that first. Very much enjoyed the video mate I’ll be watching from now on.
As a mechanical engineering student, im curious on how you decided to choose the sway bar diameter you ended up getting ?
Educated guess, then testing.
What are the downsides? If I going for a comfy ride will this make the ride more rough?
Watch the whole video.
Fwd with a slight rear bias would be fun I reckon
It is.
left foot braking or lifting off the throttle in the corner will reduce the rear grip and increase oversteer
@@timtrial3971 Ive done that before, funnily enough that's how I wrote off my 97 Camry. It was fun while it lasted and atleast no one died, pretty bad crash though
@herniagaming I only lfb in hillclimbs and rally sprints. You don't need to on downhill. I rarely get to do it. My truck has the steering column in way
Any way we can sign up for an email service to let us know when your book is released?
Subscribe to the channel will be easiest.
As an ignorant learner, this video concisely educated me on what a sway ar IS, DOES, and HOW it does it. Thanks sir. 🫡
My rear saybar is out for deleivery and this video pops up. Can't wait to install it.
The algorithm hard at work!
Back in the day, it took me a long time to understand why sway bars change the car's balance because I couldn't find a clear explanation at the physics level. You've nailed the simple but correct way to explain it!
Oright, I think I understand. It will apply to people that have an issue with the way a car is driving, which I had a slight complain with my Honda back in the day where in original form it was way too tail happy, after I fitted my coilovers it drove way better and much more predictable but now it had a little bit too much understeer sometimes, nothing that I couldn't control but it sometimes was a little issue. I was messing with coilover dampening in front to counter it, but never felt any massive difference. Sway bar was on my list as many used to says it makes the car drive even better, but no one ever really went deeper into why that's the case. I have a brief knowledge on car suspension but far from expert. Now this helps a lot. My MX5 currently has the same issue on stock suspension, front will start understeering, with it it's a little different tho cuz often it will oversteer after correcting it, makes it fun, but it's an odd behaviour. Obviously it's an old ass car with 20yr old bushes and so on, but worth knowing this for the future, especially when I'll be setting up my 370Z. Thankfully that doesn't have any of these issues, it grips hard and is definitely a little more on the oversteer side, but very controlable and pretty predictable. Again that's on stock suspension, and I don't push it that hard so I didn't run into limits of the oem setup, I do want stiffer setup tho, purely for the driver feel, also to reduce the body roll as it's a little more than I would like.
I would love to see next video on stuff like suspension dampening and spring rates in greater detail, I may even get your book, or an audio book if that will be available!
I think the purposely made some SUV understeer is that it prevent user error that result in the car rolling over resulting in accidents for average everyday driver.
Nearly all standard cars are set up for understeer.
@@JulianEdgar yes that is true because the correction for understeer is using the brakes which is easy to do for every day driver. I can imagine oversteering a SUV can resilt in rolling the car. Thanks for the video i enjoy them even as a motorcycle fabricator.
Great another upgrade I cant do. Torsion bar life 😢
You can fit swaybars to cars with torsion bar suspension.
Great informative video 👍
To somewhat bolster your explanation, but also contradict the point about kits, is that kits I’ve seen seem to significantly increase the size of one bar over the other with aim (I assume) of the manufacturer to restore the balance and reduce undesirable driving characteristics.
Assuming the manufacturers actually R&D their products, surely when sold as a set, it’s in their interest to deliver a neutral/balanced feel, unless of course they’re relying on uneducated/inexperienced customers.
Again, great explanation and not disagreeing with your overall message 🙂
Amazing video! you deserve so many more subscribers
Thank you
So given the choice would always be better so soften the needed axle than stiffen the opposite axle?
Only if the car is already very stiff in roll.
@@JulianEdgar How do you know this tho apart from feeling it?
"Oh this is quite stiff in roll" is quite subjective, do you have something objective to help understand the issue at hand?
Lateral head toss over one-wheel bumps and skatey in slippery conditions = too stiff in roll.
@@JulianEdgar Still subjective somewhat but at least more to grasp at. Thanks.
[Shrug] Both are quantifiable if you wish to go to the trouble. Eg Measure RMS roll accelerations over one-wheel bumps, and compare circular skid pan times with and without rain with varying degrees of roll stiffness. Anyone can make things more complicated than necessary!
Yes this man knows what he is talking about.
Followed his suggestion on a Volvo xc70 witch is very soft and has a lot of understeer from the factory.
Replaced rear from 20 to 25mm and also replaced front from 24 to 26mm.
Amazing difference. Of course loosing a bit traction in off-road and full out suspension travel limit, but not hardly any noticeable compared to gained feel of handling ferormance👍
Why'd you stiffen the front if you already have understeer? Put back your original one and it'll be even better.
@@nesmio7378 He stiffened the front - yes, but it got _softened_ in *relation* to the rear sway bar, and so it overall reduces understeer.
@@LateralTwitlerLT Well yes, but why was there the need to upgrade the front swaybar then? Perhaps he felt the car was rolling too much as well? If he ONLY wanted to reduce the understeered then there'd be no need to upgrade the front also. Was just gonna ask him about it.
A rear sway bar was my first modification to my car, it sharpened the handling on my FWD car in a lovely way. After that every other suspension and wheel change just compounded the sharpness in a complimentary way. Best value/dollar modification that is noticeable right away in my opinion.
You wouldn't believe the crap I've heard about sway bars... "it turns independent suspension into a live axle" is my personal favourite
My car is plowing straight in winter. It's really annoying me, sometimes I even handbake a bit to help it turn. I thought that I can fit a thicker rear sway bar from different trim, but this is already the thickest there was. But I never thought about going softer in front, because I hate body roll. There were some thinner ones on this model.
After this video, I am thinking maybe I will also give it a go with the softer front. Maybe i will like it.
Do you know the spring rates of your MG4?
No.
I have a 2013 Audi s4, and like most audis they tend to understeer because of the engine being so far forward. By far the best upgrade ive done was a larger rear sway bar, and it will even get a little sideways now if i push it hard enough.
Thank you for the wonderful and concise video. I can only speak from off-road community, but this kind of clears up why disconnecting front sway bar can improve cross axle articulation, more effective than removing both sway bars. I also read above in comments that a pair of stiffer rear coils achieve similar effect to a stiffer rear sway bar, but can it potentially improve cross-axle articulation, on 5 link solid rear axle vehicle? If you draw a simple diagram, coil springs on a 5 link solid rear axle are also pushing down opposite wheel as the fulcrum is the other wheel.
How would i get a custom sway bar made for a price of a tire lol?
I got mine at Signature Swaybars. AUD$400.
I never knew-probably due to inexperience-exactly why many road cars have both front and rear sway bars if having only one could compensate for the steering imbalance after designing in flat-ride spring rates. The drawback of having a sway bar is that the left and right sides become coupled, reducing grip on one-wheel bump scenarios.
One thought is that having both sway bars might be necessary because designing the control arm nodes to have enough camber gain and enough travel while hitting ride frequency requirements could be challenging, so the easy way out would be to add roll stiffness by putting stiff sway bars.
Another idea is that higher roll stiffness feels more responsive; thus, it appeals to younger folks.
Thank you sir! This was very helpful!
What if the car has 50/50 power distribution? (2022 WRX) Also, is a stiffer sway bar makes the ride quality worse? The car is already very stiff.
Start with what the car is doing that you want to fix. Stiffer bars make ride quality worse.
@@JulianEdgarall right! Thanks!
@JulianEdgar would a front strut tower brace have the same effect as a front sway bar, ie increasing under steer when installed in isolation? Considering installing on my 2016 BMW 428i and have read reviews that people feel it on turn responsiveness but not necessarily handling balance
A strut brace has an utterly trivial effect compared to a sway bar.
No, they don't do the same thing.
Great explanation! Getting an upgraded rear sway bar for my Golf GTI was a game changer.
Thank you for your work. I look forward to more of your content.
Thank you
Will this apply to a pickup truck with a live axle at the back? Thankyou
Yes, but because of the variation in rear load that is possible in a pick-up, you tend to be more conservative in specifying a thicker rear bar.
@@JulianEdgar cheers, I learned alot watching your videos throughout the years.
3:29 looks like the Dunlop SP Sport Max 060+ tyre I just fitted to my Freelander 2 today 😅
Sway bars almost seem too easy, but when you experience the before and after, it seems ridiculous not to do it first. Great explanation! Interested in buying your book:)
Amazing advice more people need to hear. It's almost better to be modifying on a budget at first, as you look to really effective solutions like sway bars before someone can sell you a set of expensive coilovers or suspension 'stage' tuning kits that make any modern car far too stiff,, too low, and disconnected from the road.
By "stiffer" swaybar, do we mean a fatte one? Also, what effect does installing stiffer swaybar bushes have in relation to under/oversteer?
Stiffer usually means fatter, but it could also mean changing the lever arm length, or (to a lesser degree) changing the sway bar bushes to firmer ones.
Like Julian said, changing the bushings will change the wheelrate, but not very much.
Bushings are components in installation stiffness, which is a second spring that works in series with your suspension spring. Making that second spring stiffer will mean you have more rate "left over" and less of it is "lost". This of course will come at the expense of more wear on the mount that the bushing is attached to; solid metal ones might snap the mounts off.
Bushings, even rubber ones, are very stiff, but the wheel assembly is typically stiffer, so it's a bit effective to increase the rate of the bushings for higher IK (installation stiffness).
The catch is that how much IK affects your wheelrate depends on the input rate of the spring itself. Very soft roadcar bars might only lose let's say 2% of rate between OEM bushings and metal ones, while stiffer racing ones might lose 20% and so on.
What stiffer bushings WILL do is generally decrease slack in the system, which reduces the size of the "dead zone" where the bar isn't activated but the wheels have deflected.
Thank you for making this video. I read stuff about the rear sway bar, and this clears things up even more. Just one question. Is there a huge difference between a rear sway bar and a front strut bar?
Thanks.
Yes, one makes a huge difference and the other typically a trivial difference.
A rear stabilizer and a front strut bar don't perform the same function and are incomparable entirely. One is a spring, the other is an elastokinematic component.
@@ArchOfficial Ah I see... Thanks for clarifying.
Lovely video, I intend on getting into motor racing be it time attack or wheel to wheel in IPRA or similar, these videos are amazing to watch. Thank you for the time you take to educate.
I think there needs to be a follow up on how stiff suspension interacts with stiff or soft. Such as what happens if you have radically soft suspension on stiff anti sway bars.
On dirt track cars, some people on a tight budget outright remove the front sway bar to get more over steer. They handle like crap but it does seem to work