WHERE IS LIFT OFF OVERSTEER????????????

The Caterham Academy at Curvelo Short is a good test-bed for lift-off oversteer.

 

Copa Classic for-instance the Passat Classic FL?

 

I went in to try the GT3 Merc and it is pretty sensitive to lifting once I lowered preload and increased coast ramp. But I still get understeer at higher speeds even if I lift fast and turn in. Telemetry shows identical rear tire speeds. If I really chuck it in with some trail brake the diff opens (according to telemetry as well) and I get too much oversteer.

Even less preload, but lower coast ramp (more locking force) is better I think, but also rough. I struggle to find a happy medium with it, because there doesn't seem to be middle ground with this diff. Perhaps this rough transition from full lock to partially open will see improvements in the upcoming updates?

Anyway I wanted to say this, because there is definitely improvement here and you can get liftoff oversteer if you want it via setup changes. But I also feel that the diff behavior is too erratic to trust so it's not the "good kind" of liftoff oversteer once it opens. And still seems to stick closed at high speeds even with dangerously open diff values. So no matter what the default should be and how much liftoff oversteer is good, or if high speed rotation should come from other factors, this behavior doesn't make it easy to tune the diff response to each driver's taste.

 

Hi oez,
Do you do the merc tests w tc off in setup? U know setting tc in setup to 100?

 

I use default TC. Does/should it affect this? Anyway after gathering my thoughts about this since yesterday, I think GT3 is not the best class for clear liftoff oversteer as it's quite clinical and high aero. It operates with quite narrow slip angles so any kind of oversteer quickly becomes negative.

Although I think we can still wonder if it should demonstrate more understeer on throttle than off throttle at high speed or if that's just something a certain other sim teaches us to believe. Either way the Merc seems to behave quite smoothly in hairpins with the default diff settings.

Speaking of liftoff oversteer in general. I tried achieving liftoff oversteer with the spool (always locked diff) Super V8. It is possible if you time strong turn in with a quick lift as in try to maximise weight transfer. But you're basically making the rear slide just a little bit so it can no longer resist rotation. Otherwise it'll fight back and diminish the front tire weight advantage. Trail braking also works nicely and you can be quite aggressive with it, because the locked and stable rear won't let the car spin that easily and you're not absolutely chucking the car at the same time. Both are a nice test of general weight transfer and how it manifests with a not-so-elegant setup like the Super V8.

 

TC in GT3 cars typically works by modulating the throttle temporarily if the observed amount of (longitudinal) slip exceeds a set threshold. So if you are coasting, there should be no way for TC to interact and LOO should remain unchanged. But if you are just lifting slightly, there might be an additional effect from the TC that may or may not work in your favour. You can monitor this in the telemetry by comparing Throttle (TC output) and Raw Throttle (driver input) -signals.

I believe the AMG should not exhibit a lot of LOO in normal race settings. Firstly, the car is front-engined so the amount of back-to-front weight transfer is less than in mid-engined cars. The aero balance is usually set so that the car understeers at high speeds, which should also reduce LOO. Furthermore, the AMG has a long wheelbase, which makes it more stable and less likely to rotate. The beauty of the AMG is that despite all this, it still turns fine in slow corners and with help from some additional TC can get reasonable traction out of them.

 

Yes, let me correct something I've said a lot before: I mean the sensation that there is more weight on the fronts and it's marginally easier to rotate with steering. Sometimes it gets into useful oversteer (within optimum slip angles), sometimes it's just elimination of understeer. As said full blown oversteer is a disaster with these particular cars although anything within slip angles is fair game to me. And even slight oversteer is still oversteer.

It's my belief that the detailed shift in the car's balance seems to be missing thanks to the sticky diff, that's all. You can now sense it at lower speeds and this might be a function of lack of downforce or the diff being more compliant at slow speeds. But I'm no expert with real life GT3 experience. I'm as easily tainted by other sims as everyone else. I see it as a fallacy to say "sim X does it". So I'm merely wondering if the diff should stick at reasonable settings like it does, because I believe it diminishes a detail in car response.

On the other hand, balancing throttle oversteer (the little amount you can get away with with these tires) is a joy. So that's something!

 

Curious if you have tried increasing slow rebound in the rear of the cars? IMHO, all things be constant, stiffening/increasing slow rear rebound helps increase LTOS.

 

The Supercar has it in spades. I was also in the Carerra Cup 4.0 @ Suzuka and was getting plenty coming into the right hander before the underpass...

 

This is so strange. I've been Nords lapping a tonne lately and use lift off oversteer all the time? Are you expecting the backend to fly out or something? I just use it to avoid understeer scrubbing on exit...

 

I am glad that it is finally being addressed. the whole time i had the feeling that driving aids were still switched on at the rear. like a spring on the rear axle that pulls the car straight again and again. with other cars (formula 3, stock car), the rear is closer to the expectations. In my opinion, this criticism has not yet been publicly discussed, or I have not yet seen it. most youtubers do not analyze driving behavior in any way. feelings are always spoken of. ams 2 also feels good, but many cars are not really real. no setup can replace this element. if I drive full wings at the front and very low at the rear and the handling hardly changes with regard to oversteer, then something fundamental is not okay. I am pleased that this topic is being discussed here. many thanks for the many contributions. I hope that Reiza gets a grip on the physics model and can present us with real physics.

 

It is discussed and has some work by devs (wip) and has been for some time. Further reading from just some of the threads for yourself and other newish members. Ref to just 2 of the car class's below
Vintage formulas drivability
Formula-Retro drivability
+
Physic discussion thread
Short answer to your op would be yes and yes (there is a lot to read in threads but worth it. imo)

 

Can you provide an example of a winged car where running with zero rear wing produces no negative snap oversteer characteristics?

 

try the Formula Classic gen. 1 with 18 to 2 wings. If you try such a constelation in rf2 or ams 1, you won't get 2 curves far. an extreme example is the retro. But even with other cars, an unequal ratio is suspiciously good to drive. Front-heavy wing adjustment is also not a problem for Formula 3 cars. The tail slides then, but so slowly and gently that you can roll a cigarette at the same time. in the past i have driven the reiza cars in ams 1 and rf2 and compared them. in ams and rf2 the reactions are pretty much the same. in ams 2 not. but we know that they are not ready yet. we just want to understand where the problem is.

 

I'm not sure but I think I might be seeing a slight effect when running the default setup with 0 rear wing:

 

when turning into the depression, the rear seems to be relatively stable. but when you accelerate, the rear axle is extremely vulnerable and breaks. it doesn't go together. ams 1 has been widely recognized for its physics. ams 2 not yet. and it's like any other sim now. nobody talks about these problems. nils heusingveld was always very transparent at this point and admitted his own mistakes. but i don't expect that from reiza either. that would be asking too much. The second point that amazes me is that only a few see these obvious defects. at least i got this impression.

 

That's because your springs are compressed by the centripetal force going through Eau Rouge, which increases the grip, whereas when you go over the crest at Raidillon it's the opposite and you spin off if you don't have enough rear downforce. That is a very typical way people crash at Raidillon.

 

Hehe try this with the Sauber groupC.
And you dont have to lower the Rwing

 

Sauber C9 has very pronounced lift off oversteer going through Bruxelles.

 

Now that we have v1.1.3.5, I've done some testing at Interlagos, where the Pinheirinho corner (the slow compression left-hander) is a great place to test for lift-off oversteer. I've also tested at Brands Hatch, where the Druids hairpin is great for testing this.

The following RWD cars with LSD have very clear lift-off oversteer, even on the default setup:

• Sigma P1
• Porsche 911 GT1

The following RWD cars with LSD also have it to some degree, at least if the diff is opened:

• All GT1/3/4 cars, except maybe the Camaro
• BMW M1 Procar (set clutches to 2)
• Ultima GTR Race (smooth throttle application required)

Unfortunately, aside from the Sigma P1, no prototypes with limited slip diff seemed to have any lift-off oversteer, even with some extreme setups that I tried. And I'm surprised that the Porsche Cup didn't seem to have lift-off oversteer when all the other Porsches have it, and the AMS1 Boxer Cup is famous for having it.

I would love to hear from others here if you have similar or different impressions as me regarding lift-off oversteer on v1.1.3.5