A quirk of the physics I've found - mid-corner turn-in oversteer?

First of all, loving the game. Feels amazing to drive. Other than the bumpy camera issue for which there is another thread, I'm only really having one issue - weird behaviour of cars when adding steering angle. Let me explain:

I'm basically experiencing a weird sort of snap/turn-in oversteer mid corner. This happens with every rear wheel drive car in the game, and to my totally amatuer senses feels very alien.
Mid corner, I'll be in steady-state constant cornering, somewhere near the threashold of front tyre grip, and for whatever reason, rightly or wrongly, I'll try to add a touch of steering angle. Now, normally one would expect this to cause understeer, as you're turning beyond what the car can handle, but what seems to happen in AMS2 is that the front outside tyre grips up suddenly, turns the car and then lets go. The result being sudden transition from understeer to oversteer and back to understeer. The whole time I can hear the front outside tyre scrubbing, and the forcefeedback would have me believe I am at or near the limit of front tyre grip, and yet suddenly there is more.

This issue was definitely more pronounced at the launch of the Early Access than it is after 0.8.2, but it is definitely still there. I can reproduce the issue easily with the V8 Supercar at Adelaide, especially in the slow speed 90 degree corners, as well as in the Formula V10 at Suzuka, specifically through the esses and Dunlop curve, also Spoon 2.

I have spoken to a few other people I race with and they have experienced a similar issue and I was wondering if anyone else on here had also felt this strange behaviour. This is NOT lift-off or on-throttle oversteer, it happens mid corner, both in coast and on power, it is sudden but it does not require a sudden movement of the wheel. The it basically feels like the front tyres gain grip with steering angle, which is clearly wrong.

 

What you describe is exactly what I've experienced when playing Pcars2. Only there, It seems far more prevalent among most, if not all cars. I was surprised to find that I was never really able to solve it with car-setup changes. In the case of AMS2, Reiza seems to be able to address it although, perhaps some cars still exhibit such behavior and need some attention (?)

 

There is a point where understeer can scrub off enough speed such that the tires can grip again. This can cause snap oversteer depending on how much steering angle is already applied. The Madness engine properly simulates this "speed scrubbing" which most others do not.

I cannot tell just from the description if this is what's happening here. A video would help.

 

I figured that could be a factor, along with heat build but, it always seemed too extreme in Pcars2. Then again, I've not driven under such conditions much in RL either, mostly limited to Autocross where long high-speed corners are not common.

 

I think the Stock Car is very sensitive to throttle inputs mid corner, more than it should in my opinion.
You can minimize by softening the rear, tire pressure, roll bar, dampers, but then i just get an unresponsive car in high speed stuff.

 

I find this bit puzzling. The only reason I would add more steering angle is because I want more steering. If I want less, I relax the steering angle.

My assumption is you are not at the threshold of front tyre grip, though given the snap oversteer you probably are at the limit of rear tyre grip. Maybe its the rear grip you are hearing and feeling rather than the front grip.

 

Whilst increasing front-end grip as the speed reduces seems sensible, it shouldn’t instantly go from understeer to snap oversteer. It’s should be a more gradual process unless the rear wheels suddenly lose grip.

 

Can't say I remember it from pcars2, but then again I was too focused on the kerbs in that game

 

It's definitely not due to scrubbing off speed. As I mentioned it's a snap, and it happens immediately. Since the latest patch it does seem to turn back into understeer after a short time, but it's the initial snap that's confusing.

 

It isn't due to throttle inputs, as it happens both while carrying a constant throttle as well as in coast. Regardless it's definitely an issue with the front tyres not the rear, as the car doesn't immediately slide until after the car has already begun to turn more.

 

While I am in no way saying I am a good driver, and perhaps I am driving it wrong, the result still seems extremely unintuitive. The front tyres seem to be at the threshold of grip by all evidence available. The Audio indicates scrubbing, the forcefeedback is right on the curve before it drops off due to understeer, the car is pushing every so slightly. It also happens when my inputs would normally cause understeer, for example high speed on-throttle, even over a crest like Dunlop at Suzuka. Having never driven a car on track in real life, i can only base my expectations on what other sims do, and none of the sims I've driven (AC, ACC, rFactor 2, iRacing, R3E etc) seem to have this quirk as well. Someone on here mentioned pcars2 might do it as well, although I can't remember every experiencing it.

 

Can't say that i have sudden mid corner oversteer on coast, for me it's on throttle, it's very sensitive, still driveable, i've learned to live with it, but very sensitive.

 

It sounds like your are describing 'fishtailing' although Dan Gurney started the trend of using a motorcycle term to describe a similar thing as in 'having a tank slapper'. I think there's a lot of underlying physics involved but it's when you come off the throttle so the rear is no longer putting power down and the rear suspension becomes unloaded, the rear slip angles increase and the tyres lose grip but the front still grips causing the rear of the car (or bike) to try and overtake the front. It is snap oversteer one way, then as it is corrected it becomes snap oversteer the other way like a pendulum.

 

I would say I've noticed this behaviour. It's definitely more noticeable at lower speed corners. Virgina raceway is a good example.

 

It's not always that gradual in real life unless you were understeering a lot. If you are understeering a lot, then there is the time it takes to scrub off enough speed for the tires to grip again (and then it depends on how much the tire has heated up during that event). If it's only a little understeer, the moment the car regains traction is literally within a split second. Many drivers actually use this as a driving technique. They will enter a corner a little hot, let the car scrub off some speed and then get back on it to drive through the corner.

Hard to diagnose without video and/or telemetry data. It could be an issue with the tires in their current state or it could be expected behavior.

 

Definitely not, because again, this happens both on power and in coast. The issue arises when I add steering angle, not when I move the pedals. Obviously the oversteer is more pronounced when the weight is on the front, but even on full throttle with a big hefty car like the V8 Supercar squatting through a corner, added steering angle past the point of understeer can still cause oversteer.

 

For it to happen it does not require me to have been understeering for any amount of time, though. If i simply turn in initially with too much steering angle, however gradually, the car with turn past the point of rear grip. The feeling is akin to the front outside corner diving suddenly. I will try to get a video up when I have time in the next day or so.

 

I'm glad others have noticed this I noticed it along time ago in Project cars 2 when I realised to go faster you had to give a little more steering lock than seemed natural .This larger slip angle seemed to be the difference between pc2 engine and the rfactor engine.The larger slip angle is not the problem in real life and I'm a real life racer or I was , the slip angle is quite big but the way project cars 2 gained grip with more slip angle felt a little off and I can feel a little of it in ams2 even though I love ams2 physics, once you feel it you cant unfeeling it.

 

There are some tires that in real life, that love/have large slip angles. Hoosier A & R line tires are such. The sloppiest lap you think you've driven with those will likely be the fastest. Other tires like the Kumho V710 or Toyo's don't like large slip angles and prefer tidier driving.

 

I’d agree if you had a lot of understeer and consequently a lot of steering angle into the corner and you were slowing down quickly. If it’s only slight understeer, your steering input probably wouldn’t be enough to give the instant, snap oversteer we’re seeing here.