What's up with the Stock Car (diff)?

This is a question for all the experts in our community (and I'd love to get some input from the devs as well!):

What is up with the Stock Car V8, particularly the default diff setting?

In order to understand what I'm asking let me go into detail:
During the later phases of Early Access I noticed that the Stock Car V8 was exhibiting a lot of behavior that seemed very strange to me, especially considering its AMS1 counterpart was, for me, one of the most impressive cars in all of sim racing. I did write it off as some things simply not being properly calibrated yet and wanted to wait for 1.0 until I gave it another spin.

So far I've only driven the Sprint Car and Stock Car V8 post-1.0 - the former to dial in my FFB (something like 100/60/55 is mostly working okay for now) and the later because I consider it to be a large part of the "meat" of this sim; that assumption is probably not that far off considering earlier titles like GSCE and GSC2013.

Unfortunately the Stock Car exhibits a lot of behavior unlike its AMS1 counterpart when using the default setup: It has a tendency to understeer in mid to high speed corners, whereas it will often suddenly suffer from either lift off or throttle-induced oversteer on corner exit, usually in low to mid speed corners. All of these things seem to happen in a rather unpredictable way.

Of course there are other issues, but things like the brakes locking up too easily can at least be dealt with by reducing the brake pressure (85-86% seems good enough for me) and/or bias. But overall the car feels like it has less stability (downforce?) than it should, and allows carrying less speed through turns than would be expected.

I remember a few weeks back during early access I tried fiddling with the differential with some limited success, because the type of the issues I was seeing could be explained by sub-optimal diff settings. So I had a hunch and switched the diff from Clutch LSD to Spool/Geared LSD.

To be honest it was hard to believe how huge the difference was. The car suddenly feels much more planted, doesn't slide all over the place and my pace (on Brands Hatch GP) got more than 1.3 seconds quicker on the next lap. After changing Bias Ratio for Power and Coast to 1.3:1 and 1.1:1 respectively, I could easily gain another five tenths (but it would've been as much as .7 seconds if my line through the last turn had been cleaner). So pretty much a difference of 2 whole seconds between the default setup and one with different diff settings.

Now my memory could be fuzzy and it had been quite a while since I last drove the Stock Car (2017) in AMS1, so I just gave it a quick try on the same track. And I noticed a couple of interesting things:

1. The car was MUCH more planted in all areas except when going over very specific kerbs.
2. While the car was more planted and felt like it had tons of downforce compared to its AMS2 incarnation, it also felt much more simple. My goodness, as good as AMS was, the cars feel so much more alive in AMS2. I was shocked.
3. Even though my lap was decent (for a quick try, anyway), it was around ~3 seconds slower than my best AMS2 lap on the same track - even if the AMS1 version was far easier to drive for the most part.
4. AMS1 didn't differentiate between different types of differential (see what I did there? ); there are only Power, Coast and Preload options, and nothing else. Is this maybe why the difference between the AMS1 and AMS2 version of the same car is so huge?

So to all experts out there - why does the Stock Car V8 (not the 2020 one, by the way; haven't tried it yet) drive the way it does in AMS2? Why the big difference between this one and the one in AMS1? What's the reasoning between the default diff setting when it makes the car behave so unpredictably? And what else can I do to make this car feel more planted (i.e. increase mechanical grip and maybe get the most out of the available downforce as well)?


P.S.: This may sound crazy, but the Stock Car V8 is - for me, at least - the only vehicle in AMS2 that I've tried that doesn't feel at least as good as its AMS1 counterpart. The majority of vehicles feel better to me than they ever did, and all of them 'make sense' to me. This is the only exception from what I've seen, hence my confusion.

 

Thankyou for your post.

I largely thought there was something wrong with my set up in AMS2 as a lot of the cars have a similar lack of feel and predictability. I tried a lot of FFB setting combinations and haven't found anything to cure the feeling across multiple cars except adding more aero on the Formula cars. And even then there's a large grey area without feel at lower speeds.

I loved the SuperV8 and Stock V8s of AMS1 and just can't get anything like the feeling I had with both in AMS2 V1.0. There's no predictability and I have little no feel.

So to me it seems something with the physics change from gmotor to MADNESS engine has caused this change in feel.

 

I keep on asking this to Reiza : give us 2 different kinds of default setups, a safer and a more aggressive one, like other sims already do.

 

Agreed; that is generally a good idea. Not sure how much work it would be, though (lots of testing required, I would assume). On top of being practical it would also be helpful for a lot of players to see which specific settings are more on the safer side for a particular car and those that are not.

In case of the Stock Car V8 it's not even a case of safe vs. aggressive though, but rather of hard to drive & slow vs. balanced and fast. I still can't wrap my head around some of the Stock Car's behavior, like the tendency to go into a spin once you finally get it to turn quickly (especially when bumps on the track are involved).

 

Stock Car or V8?
Brazil or Australia?

"Stock car v8" is a bit vague, I don't understand which of the two you are talking about

 

AFAIK the Australian one is called V8 Supercar.
I also mentioned it was not the 2020 version, so I thought it was obvious I was talking about the Stock Car Brasil (2017, I believe).

The funny thing is, I didn't like the old AMS1 V8 Supercar very much, but I find it pretty enjoyable in AMS2. Did a few laps around Bathurst earlier today - a match made in heaven!

 

I've found that a lot of the problems come from the diff settings as well, usually coast or pre load being too high or low, also one of the main fixes for me is turning off Low force in FFB 0-5 max, it seems to affect the cars in slow corners, almost like a fake spring effect, making the cars want to over rotate.
Seemed to fix nearly all issues for me, apart from the most recent DLC, which need work.

 

In general the clutch pack differential on default setting seems to rely too much on preload (removing it makes the diff almost open in traction).

Lower (a lot) the preload, and start to play with power ramp angle (decreasing it) and coast ramp angle (increasing it) until you find your sweet spot.

 

I was curious after XTRMNTRXERTNS2's post (maybe an easier username next time?)
I can tell you, dear friend...if you find the 2017 Stock Car oversteering outside of corners, don't even bother trying the 2020 one..there this behaviour is even more extreme, feels like driving a bouncy castle

I tried with your changes (spool/geared LSD ON, clutch lsd OFF) and the car became much more stable in corner entry and mid corner, pointing exactly where I wanted. However, the oversteer on corner exit was still there. The car just wants tu curl on itself like a sleepy cat.
But you say the car became quicker...I didn't see that. It got better on corner entry and mid-turn, but actually it was slower throughout the corner I found.

If you have a track like Londrina, with repeated hairpins AND also gradient changes through said hairpins..that makes for horrible driving... waiting ages tip-toeing through the corner with throttle doing "yes-no-yes-no-yes-no" only for the mid-corner camber to throw you away.

Then I tried the 2017 Stock Cars again, and found the problem less extreme...normally there is less oversteer out of the corners, only when the conrer has an altimetry change. But when it happens, it happens big time. You slide in Brazil, and the car flies in Bolivia

Then again, if LSD was the solution Syd Barrett would have become F1 World Champion....

 

Nope - I've been using this one for more than 20 years and I'm sticking to it!
(It's also easy if you get it - it's just Exterminator2000 without any vowels or zeros)

I did, actually, and found it to be less extreme than the 2017 version. Only tried it on Brands Hatch GP, though. That being said, it doesn't drive great either with its default setup. But it's fascinating to see how different two people perceive the same cars; I'd say driving style is a large factor here, and I'm the first one to admit I'm not as smooth during the transition from braking to turning into the corner as I probably should be. For some reason I tend to throw the car around more than in, say, Assetto Corsa Competizione (where smooth easing of the brake pedal when entering a turn is paramount!).

That's true, unfortunately. I mean, I get that the Stock Car has a lot of torque and power in the rear and no dirty little helpers like traction control, but even with moderate amounts of constant throttle it just wants to spin. At times it feels like has a rear engine with the amount of perceived weight in the back.

Well, part of that may be due to driving style. With the default setup I didn't have much confidence in the car, so at least part of the lap time difference may be due to that. I agree that it has a tendency to be slightly slower and a bit more under-steery throughout some turns, though. Still, I was kinda shocked how big the immediate difference was.

I would like to try Avoletta1977's advice, though. Maybe fine-tuning the clutch LSD can get similar or even better results. Though I am still not entirely sure how changing the number of clutches will change its behavior...?

Haven't tried that yet, but I will. From the sounds of it the car will need a lot more fine-tuning, then...

Yeah, it's almost impossible to catch once it starts sliding. Like I said, feels like a rear-engined car at times (think the first generations of 911, for instance).

 

if LSD was the solution Syd Barrett would have become F1 World Champion

never laughed so hard on this forum

 

Number of clutches is increasing the locking torque proportionally to the number itself.

 

Today I could finally try out your suggestions and I want to thank you so much!

The default settings for the LSD are really way off. In the end I settled for these LSD settings:



Clutch LSD
Preload 20 Nm
Clutches 4
Power Ramp 40 deg
Coast Ramp 60 deg

This made the car much more predictable and enjoyable to drive. There is a bit of understeer going on in slow to mid speed corners, but changing the rear toe in setting to 0.1 degrees quickly solved it. Rear aero may also be adjusted, I tried increasing it by one click (from 7 to 8 I think) and it is wonderful for tracks like Jerez.

With these settings the car retains its character, but at least it doesn't try to kill you at every occasion. The rear still gets squirrely every now and then, particularly under power, but that is to be expected. Overall I feel like this should be the actual default setting for this car.


With regards to the Geared Diff settings I posted earlier: There was actually an error on my part. Spool must not be enabled, otherwise every other diff setting won't do anything! Just thought I'd clarify that.

 

I just leave a comment on another post, so I copy that post here because it's the right place to discuss it. Thanks.

"I was trying the new 2020 Stock Car V8 (the Corolla one) and I was not comfortable with the handling, very "twitchy" and somehow impredictable handling, snap oversteer, lots of WTF moments. I adapted eventually, but I didn't feel ok with the car.

After several laps, went to pits and changed diff settings from clutch to gear driven, and the car changed completely. It's a lot more stable now, predictable through corners, I can push it hard now.

So I was wondering, is the clutch the real diff for this car? If the real life car has a clutch diff fitted per regulation, why I can fit a gear diff on it?

On another note, I think the handling for default setup for this car needs to be like the handling I experienced by changing the diff: Much more friendly and stable for newcomers than the default setup with the clutch differential."

I'll try the suggested values for clutched LSD reported here later on, thanks.

I did a 40 mins race at Londrina and found the car a lot better with the geared differential, so I think it's a lot of driving style and may be adaptability involved on this change. And a lot of driving skills of course, I'm not so fast so it can explain why I need a more planted car

 

I’m glad you find something that suits your driving.

‘Spool’ fully locks the axle, so any other setting makes (correctly) no difference at all.

I also agree with you that default setup for differentials are quite inappropriate for most of the cars.

Even full open diff ones may benefit from some internal friction (‘fixed’, speed and torque dependent) that seems not to be modeled at the moment. This could be easily implemented by using a combination of clutch LSD with low preload and ramps close to 90deg and just a bit of viscous coupling.

 

I just drove the 2017 and 2020 Stock Car (both Chevy) in Brands Hatch GP and was with the 2017 version 2 seconds faster. The 2017 Chevy also felt much more stable even in the default setup.
I'm not very familiar with this cars and I just assume that the Regulations were changed between 2017 and 2020.

 

Yes, for 2020 they are now using the road car body over the tubular chassis which makes the car heavier and less aerodynamic. Also there was a bump in power. It should be slower in general.

 

Thank you for the clarification. Chassis change explains the different behavior between the two cars.

 

This setup is awesome at Bathurst. I just tried it