TL;DW - Differential preload explanation.
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- เผยแพร่เมื่อ 27 ก.พ. 2020
- How to use the differential preload to fine tune your car handling.
Why it is confusing, how it influences your car handling in different situations.
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Power (on throttle):
locked diff:
- oversteer in low speed
- understeer in high speed
open diff:
- understeer in low speed
- oversteer in high speed (or less understeer / better turn in)
Coast (off throttle):
open diff = more oversteer
locked diff = more understeer (high speed)
less preload = diff is more open
I'm gonna save this. Always keep forgetting about it after a week or so xD. Thank you.
so when cars drive normally without turns, the two wheels are locked or open by default?
@@terrylu4894 the setting of the preload decides HOW MUCH they are locked even when driving straight. In an extreme situation where the diff is 100% open both wheels are delivering power but it’s the subtle changes in rotation from one wheel to another (bumpy road for example) will have a different reaction depending on pre load.
Why look up someone elses set up when you can learn your car and make the changes on the fly based on how it's behaving on the track?
Teach a man to fish. These videos are a treasure
The differential serves to ensure the traction of the wheels, even if they turn at different speeds, preventing the car from spinning by adjusting the movement. With a pure open differential, if a wheel slips, the torque directed to the one with the most traction is automatically reduced. And this is the limit of the open differential: in practice, when one wheel loses grip, the other no longer discharges power. A compromise must therefore be found between:
open differential : ideal situation for the curve because inner and outer wheels can turn at different speeds and adapt to the fact that the path of the inner wheel is shorter than that of the outer wheel;
locked differential : ideal for acceleration or release traction (straight).
The parameters that regulate the degree of differential lock in acceleration ( power ) and release (coast) in the GT3 are fixed for homologation while the preload modification is available ( preload ). In practical terms, the preload can be seen as a value that determines the intervention times of the differential ; when this intervenes, there is a different distribution of the driving torque between the two axle shafts and therefore their different rotation speed.
Fully open differential in rear-wheel drive cars: when you face a slow corner (therefore first or second gear), the internal drive wheel obviously has less load than the external one; you press on the throttle and at a certain point the inner wheel (with less load) begins to skid. In this situation and with the differential completely open, the inner wheel, the one that skids, will receive all the drive torque (skating even more) while the outer wheel will not have it completely. This will result in the car having less traction but will also be more stable and won't slide sideways (no oversteer). At high speed, in fast corners, a situation in which the engine torque is not so high as to generate loss of grip of the inner wheel, the car will therefore have no oversteer problems (better turn in).
Fully closed differential (locked differential) in rear-wheel drive cars: when you face a slow corner (therefore first or second gear), the internal drive wheel obviously has less load than the external one; you press on the throttle and at a certain point the inner wheel (with less load) begins to skid. In this case the drive torque will not go to the internal one (which skids) but will be equally divided between the internal and external wheels. In this situation, the outer wheel (with grip) will generate more thrust (traction) than the inner one and this will cause power oversteer. At high speed (with high gears), in fast corners, a situation in which the engine torque is not so high as to generate loss of grip of the inner wheel; therefore both wheels will push in the same way (having the same grip and equally distributed drive torque), so we have understeer.
This is the reason why the differential (free or locked) determines a different behavior of the car based on whether we are: with first or second gear (slow curve) or with high (fast cornering).
The situations that may arise can therefore be summarized as set out below.
Low preload value:
slow curve, to be addressed in first or second gear, less traction and slight understeer
fast cornering, to be tackled with 5th or 6th gear, stable car (no understeer) and better turn in.
High preload value:
slow curve, to be addressed in first or second, more traction and oversteering behavior
fast cornering, to be tackled with 5th or 6th gear, understeering car.
Perfectly explained. Thank you 😁
You’re doing gods work with your setup videos, seriously lol. This is exactly what the sim-racing community has needed for so long. Not online forum debates about which does what, and often results in the wrong information being relayed, or small 5 minute explanations which leave more questions than answers.
I’ve always wanted to try tackle setups but struggled to find good, clear and concise explanations over the various topics. You do such a great job of explaining things. Thank you!
I’d love to also see you cover alignment in the future, and maybe how to analyze the optimal camber for tire wear, and grip. Would be great to see if you ever felt like covering it!
I know this isn't your issue, but if guys like David Perel and others want to charge for their tips and set up configs, they really need to go into detail like this man. Aris, you have helped me tremendously, so thank you!
You're one of the few who actually goes beyond the basics and tries to make us better drivers, since I've seen your video about acceleration I've tried to apply it and I always get better exits than most guys in my league.
After learning that oversteer is a symptom of getting on the power too soon, and watching your video, I am finding great success increasing the preload on the newer bmw gt3. It’s allowing me to move the brake bias rearward along with allowing me to balance the high speed and low speed handling. Somewhere between 200-250 is feeling good at Cota so far with low ride height and one less click of wing. Thank you for this video! ❤
I always turned preload down but didn't really understand how it worked.... glad to get that understanding.
First video ive seen of yours. Best tutorial ive seen for acc hands down. Thank you for helping
Man this is such a good video for so many reasons. First video of yours that I've checked out and so I'm stoked to watch more!
Thanks! Welcome to the channel!
I finally fully understood the whole concept and started doing my own setups according to what I like in a car/track combo. Amazing that I can now clearly feel the effect of changing the preload diff. Thank you sir!
this is exactly what i was looking for! thank you so much! Perfectly explained! supreme job!
Great stuff. Good job, Aris. Sei sempre un grande :)
Like always, the best explanation comes from the dev himself. Thanks, Aris.
You explained this very well. Thank you for doing these videos.
Honestly I hope Aris could be my physics teacher during my middle school😄, lessons become so interesting 💪
Awesome info. Ty for taking the time 👍🏼👍🏼
Did the same last night, softened the rears 1 click and drpped the LSD from 100 to 80, so much more stable both on exit and on trialbrake/coast. Suddenly the car becomes so much easier to handle.
Great videos Aris!
where do u soften the rears? what does means LSD? I watched all the video and I barely understood man
@@zekkai1005 LSD - limited slip differential. He meant he lowered preload. About the rear, my guess is he's talking about suspension, 2
which makes sense.
So Coenraad, in the set up page, locking the differential is lowering the number, right? Or is it the opposite, so to lock more I have to raise the value?
@@FrankVPBE Haha not sure the close or open but lowering makes the car more stable, while increasing the number makes the car more loose on liftoff and at the exit for me. Really helps a lot in the M6 and Huracan for me.
Bro, when you drop LSD you better raise by 20mg, not lower... xD
#1 game... #1 you tube channel... Aris is the MAN!!!!
It's very usefull!
So 50% is answer for everything. 👌🏻
No way! The answer for everything is 42, everybody knows that!😀
How I put it down in my notes..
open (loose / less weight) differential -
Low speed / low gear (high torque) = understeer (rear end more stable), but slower because torque is distributed to the tire that has less grip
High speed / high gear (lower torque) = oversteer (not from sliding), because there is less torque and more grip (better distribution)
Coasting / engine break = oversteer / better turn in
___________________________________________
closed (tight / more weight) differential -
Low speed / low gear = Oversteer because alot of torque being forced into both tires causing a slide on the tire with most grip
high speed / high gear = understeer because both tires have more grip and equally provide forward momentum
Coasting / engine break = Understeer
___________________________________________
Can't wait for the DLC. Love the game on PS4 Pro (Thrustmaster T300RS + Wheel Stand Pro V2).
GOAT
Pick this man a beer!
Great explanation, thx. Remaining question is: Why is the preload still 100 for the BMW setups on Suzuka ? :D
Aris is basically our cheat codes for the sim
aahaha! Knowledge is the best cheat code there is!
AAnnnddd!! Now, I gotta go racing...
By the info provided I assume you should tune Diff Preload per track basis rather than the car? F.e. you have a track where most of the corners are slow speed then you would go with more open diff (less preload)?
Aris, not sure if I missed something, but there seems to be a major error with this explanation.
The torque split of an open diff is always 50-50. In real life scenarios it may even be ever so slightly locked due to internal friction. What you said is the complete opposite.
Actually, I think you meant to say power and NOT torque! In that case I would agree. The 50-50 split will result in a higher power to the faster rotating wheel due to the speed delta (P = omega*T), but is no such thing as torque split.
please could you write in the description from which your video this fragment is taken (give us the link)
Sure thing, here's the original video and the exact time stamp.
th-cam.com/video/clA7BRvYoOQ/w-d-xo.html
So you can pretty much say that limited slip differential *IS* preload diff?
So locked diff is when you add more Nm in your setup? and open diff is when you remove Nm on your preload diff on your setup?
i have a kind of weird question to people reading this. in assetto corsa 1 when im driving cars that dont have abs like porsche 919 , 911 rsr etc i can easily control the brakes and dont lock them up but when i drive a car that has abs and i close the abs , it becomes too hard to control the brakes for some reason i just lock them up very easily. is it just because of my incompetence or is there something else causing this issue. Maybe brake gamma is different for abs and non abs cars so that when i close abs in abs cars it just locks up pretty easily?
Nice video mate. Thank you so much for your effort. But I have one small correction. In an open diff the amount of torque on both wheels inside and outside is always the same. Torque is not increasing on the inside wheel. It is of course limited by the max torque that can be transfered to the road by the wheel with lower grip. In mue-split situation the low grip wheel is spinning fast, but the output torque on that wheel is zero. So is the torque on the other wheel. That is why the car is not moving forward.
Vice versa the torque in a 100% closed diff is not the same on each wheels. Instead, it is higher on the wheel that has higher traction. For example, one wheel is up in the air and has output torque zero, and the other wheel converts the whole possible torque to the ground.
Does it also mean that yu have more control by running in higher gears ? like dont downshift to 1st gear ?
I have some, maybe stupid question. I always read at the setup guides high speed an low speed. What is the devinition of high speed and low speed? When does low speed ends and high speed starts.
Serubal low speed = 1st and 2nd gear corner; high speed would be when the aero actually affects things (above 150-160 km/h)
I've set the preload to 140 on acc. It makes the car seem more stable to me.
I think I'm doing something wrong
so when cars drive normally without turns, the two wheels are locked or open by default?
Open means ? In Assetoto Corsa its a % setting.
Also can you change these settings on the fly ( in the race from the cockpit) ? Assetto Corsa or Automobilista ? Those are what I run.
Okay yeah great.. but which end of the slider is locked vs unlocked??
More a limitied Slip explanation as a preaload isn’t it? What are the advantages of preload on a limited slip compared to an limited slip without preload, which means it is open in some cases (no rotation difference)
Γεια σου Αρη, εχεις παρατηρησει αν το πολυ preload κοβει χλμ σε γρηγορες καμπες με τερμα γκαζι?
Hope you weren't expecting a nod every time you say ok.
Actually I was... but the tech is not up there yet :D
can anyone help me tune the reiter engineering r-ex gt3? i've learned a lot watching aris's videos and still can't get rid of that horrible lift-off oversteer at high speed corners like turn 18 at spa or the start of the downhill at bathurst... please i like that car's engine sound so much but it's handling is horrible lol
try lowering the rake and rear damper bump, perhaps the rear arb as well
With an open preload is the number smaller or bigger???
Smaller=more open.
Aris.Drives many thanks here... I hope you don’t mind my adding a link to your channel in my last video. Very interesting to watch your tutorials & setup approach. I’m new to ACC on Xbox One X using the Fanatec 2.5v base & McLaren wheel. Although there’s clearly a few issues with the FFB detail, I am finding enjoyment is capable with the settings as they are as long as I use the right wheel rotation with each car.
Currently using 85% gain & 100% dynamic damping with everything else at 0%
FFB through the Fanatec wheel at 150.
Thanks for the videos they’re very informative for all us new guys to the game.
Ciao Aris sarebbe interessantissimo se capissi l'inglese ma non ci capisco niente ...
Non riesci fare un video in italiano ??
Grazie molte continua così
WTF happened? Where is the fully locked at?
..I'm starting to understand Kunos.
You got the locking diff wrong, but could explain why the differential-behavior in ACC was so very wrong in the first years and still differs to other titles. Not with the locked, but with the open differential the torque-split is always 50/50 and this is certainly not giving you oversteer on power in high-speed-corners, because the outside wheel has more friction and more travel to accomplish and so demands more power and torque. LSDs provide better cornering capabilities because once the lateral grip changes to the outside wheel so does the torque. An open diff still provides half the torque to the inside wheel that demands only a fraction of it. So an open differential is actively forcing the car to understeer on throttle in any corner similar to FWD-cars while neither V8 Supercar nor Karts are known to understeer. Even low-powered cars with 150 hp will be faster with a locked differential compare to an open one. If open diff is mandatory, race-control will check if it's not welded together.
A locked differential only provides a 50/50 torque split if you drive completely straight with matching lateral grip. If one wheel is stuck and the other in the air, the torque split is 100/0 obviously and that's why they are so powerful in offroad conditions. With an open diff it's still 50/50, but if the friction is 0 on one wheel (in a perfect world without internal friction and mass intertia of components), there is 0 torque applied and so 0 on the wheel that's stuck while the power just heats up the engine, components and spinning the free wheel.
The preload (screw) is just the value of how much both diff-sides are locking together with the wrench. It provides stability in high-speed corners, but that doesn't mean understeer. Open diff cars can easily snap oversteer off throttle during corners, but that doesn't mean they oversteer in fast corners. They can only oversteer while braking, lifting or coasting and happens in slow and fast corners.
I listened to the phrase from 10:54 13 times lol just to get it and then I started the video over to get the mechanics of it again.... I think I got it. And this was me coming in with some knowledge of how to set up.