Physic discussion thread

I apologize. I neglected to mention an important part. The cup car still had the "spikey" diff using default, but it was easily fixed by locking it a bit using a standard preload/power/coast ratio, like 80/60/30. I didn't mean to suggest there was no tire fire...lol...(new term to me).

Regarding the tire grip question. Mainly a hypothesis. I imagine a max grip tire (on a max grip track, like TT) could handle more lock (lateral/longitudinal force), but when it unlocks its more severe and snappy. A less grippy tire, might not be able to handle as much lock in the first place which could lead to more gradual opening.

Looking at the image, a fresh set of rubber might have a higher max lateral/longitudinal force, like the red line, but a more abrupt loss of grip at higher slip angles, but a worn tire might have a more gradual force curve, like the green line.

Im not suggesting that the tire model is the culprit either, just that it could be a contributing factor as IMO the tires are quite grippy. (I come to that conclusion because improperly cambered and pressured tires can set WRs on the LBs in the hands of a skilled driver, when common sense suggests that shouldn't be possible)

 

Hey, again some nice and fast finding of one of the most affected cars! (actually one, that drives impressively, but still suffers from it big time and the geared diff is actually not unfunctional, i know, this sounds like a contradiction)

First, i want to inform this thread, that this issue is known and also in process of being reviewed by Reiza Studios and also receives internal testing. I'm also involved in testing and can agree with a lot of stuff, you have found!

Some clutch LSD cars are actually way better now, especially GTs, Prototypes and other higher powered cars, but the lower powered ones still suffer and it's an ongoing process, involving many components of the driveline (some visible in the recent changelogs) and it's not the differential model itself but a combination of several things, due to the high complexicity. (Some cars, like Group A and M1 Procar even differentiate too much on power side right now, for example) I'm sometimes indeed also frustrated, it takes so much time for all these small steps, but it's how it is and things keep improving, for sure, which could also be a good cornerstone for possibilities in the future!

Yes, the G40s are showcasing, that also the geared diff is indeed affected by the driveline quirks and back then, we were able to use the F-Retro with the geared diff, that was night&day, which additionally indicates, that the differential model itself is actually working. The G40 showing different results is another indication, that it isn't the differential, but the whole driveline, needing a lot of "Fingerspitzengefühl" to be taken in the right place.

Be aware, that i can confidently say, i'm spending hours to annoy @Renato Simioni with more and more wheelspeed graphs, feedback for the workwise of different cars and can see progress on different fronts already, also discussing and learning, what might be wrong and right. I'm also looking into the threads from time to time still, to keep track of what others say, because more impressions are helpful, of course.
Therefore, keep pushing, every information is helping!!

Especially the most affected cars, where quite some are already identified, share some quirks, that need more time to look into it.

Basically: The more cars are light, underpowered and grippy, the more likely it is, that they will still suffer diff issues.

I hope, i was able to shed a bit of light at this topic, to assure you, that this is taken care of with a very high priority and awareness!!

Have faith!

 

Don't expect the snake oil super healing over night, like basically summarized, though.

Renato and co. are handling it, their work is outstanding! I'm just moaning about things being odd

 

I have to pop in and say that I just finished QCing my Porsche Cup 4.0 builds. The diff ratios make sense now and the car is ___dam wonderful to drive.

 

same

 

May you please share one of the combinations in car/track, that seem very affected to you?

 

Its my understanding that geared lsd’s don’t “unlock” like a plated lsd, so you shouldn’t technically see a wheel slip difference. They are essentially open, applying torque evenly as you apply power. The more power, the more they lock on both wheels, regardless of the difference in rotation. In the event a wheel slips, torque is simply biased to the gripping wheel.

 

The graph by @oez shows wheelspeed difference in second monitor.

EDIT: (I think, RST uses the wheelslip %age thing, right? Wheelslip graphs are good for analyzing how to optimize effectiveness of the diff, providing it works, of course, but the Wheelspeed graph is more reliable, to see clearly, if any diff is doing the differentiation.)

Of course you also see wheel'speed' differences with a torsen/quaife diff, or you could go with a spool anyway. There is also a coast side and you definetly should see different wheelspeeds off-throttle into corners.

Btw. Just looking at this animation shows me again, how genius engineering can be

The geared diff can show some reaction with very low torque bias settings and extremely aggressive driving, but of course it's not enough or "natural" yet, as we know:
G40 GT5, Velo Citta, sloppy driven lap, hitting kerbs etc.:

 

Ahh, I see. Yes, I was definitely interpreting the graph as a slip graph.