1.6 - Issues with grip

AFAIK it’s the IMSA tyres which I think are Michelin

 

Would make sense - but did Reiza actually use Michelin tire data to model the Gt3 tires ingame?
How much difference does this make?

I didn‘t spent too much time in AMS 1.6, but I did some Gt3 races yesterday on Sebring and the driving feels good, a little oversteering on corner exit is the only thing that reminds me of the slippery driving feeling a few versions in the past (never played 1.5).
But what I found was that the tires loose their grip very unpredictable. You can push and push and suddenly you spin. Since I‘m a bad driver I think the „problem“ is behind the wheel and I should be more careful.

 

The unpredictability bothered me the most, after switching from default ffb with 0 fx to default+ with 20 fx not only the ffb got significantly tighter but I can feel the rear loosening.

 

I think the problem comes from the tires on the maps, the way the GT3 reacts is very far from reality, the rear axle always wants to pass in front in all circumstances, when I talk about maps I'm talking about the entirety of the circuits when we see what it does in the grass (snow) we say to ourselves that the slip rates are abnormally too high on the whole game. And I think that the braking effect does a lot, we have the impression of braking in sand it's strange. it should add jolts in the ffb like on LMU it's phenomenal

 

I believe the issue lies with the game engine. Even if you lock both front tires, the car can still pivot left and right by responding to your input—a behavior that doesn't occur in other simulations or in reality. In my opinion, eliminating this effect would be a significant improvement. Additionally, it's odd that braking while airborne causes the car to execute a front flip, which is yet another flaw with the game engine.

 

This is the main problem with V1.6, unpredictable and sudden snapping of the rear on tires that have already warmed up. The break away on warmed up tires isn't progressive but sudden.
IMHO, V1.5 was much better in this repect, while not perfect, it was still much better and more predictable than V1.6. It seems like the testers that steered the development of V1.6 tire model pushed it more to FFB feel than realism.

 

You havnt tried the 1.6.4.2 update, have you?

 

I personally have tested it and (for me) it‘s still the same as I described it.
I‘m driving a Moza R9 base with the GS wheel, using Danielkarts latest custom FFB file.
Default (+) FFB is undrivable on a Moza base, big deadzone & heavy oscillations.
I also use Asetek Forte Pedals, but these (imo) don‘t have an effect on the sudden loss of grip.

 

I have, there isn't an improvement, the core underlying issue still remains.

 

May I ask what car(s)?

 

GT3 Gen2 cars, specifically Corvette and BMW. I think the GT3s were the only ones that got a tire model tweak?

 

You claim about Moza base and default+ is incorrect. I have R21 and no such issues (we'll maybe oscillations if I take my hands off, but there is no reason to do that). So it could be problem for you / some others, but it's not a problem for everybody.

I don't find the rear tires going that unpredictable either (and that part I found worse in 1.5 than in 1.6 onwards). The most common case it happening is in corner entry or mid corner and those can be mitigated with driving and setup changes. Unlike 1.5 or earlier, you can actually get understeer in those phases now (in something like GT3), though it's still more rear that front limited and thus prone to oversteer rather than understeer in a lot of cars.

I haven't driven those GT3's yet much after the latest update, but I except it's been improved even further now.

If I lock the fronts, I definitely get a ton of understeer, so not sure how you came into that conclusion...

 

Coach Dave described the IRL GT3 tires having a lot of grip, but when it's gone, it's sudden and not that gradual.

In AMS2, the balance is often towards rear losing grip first though.

 

Did you use old setup or reset it?

Ton of understeer, yes, but you can (barely, but still) turn the car with completely blocked front tires, which is not the case in ams1, I tried it yesterday with a caterham and formula vintage gen1. Which cant be caused by an abs bug for instance as those dont have it. Its really minimal but happening - maybe due to the contact patch moving with the caster angle..?

 

This is what exactly what is happening: When you take your hands of the wheel it starts the oscillation. Since I like to relax my hands on long straights and just lightly rest them on the wheel, this is a no go for me.
And as I said before, I feel like the Default FFB files have a very big deadzone (that can‘t be controlled with the ingame settings) and the FFB feels very light at smaller steering angles. But this is just my humble opinion.

I feel that the GT3 cars are now better than ever in AMS2 and I would choose them before driving ACC, but I still like them more in LMU or RRE. Again, just my humble opinion.
There are other great cars in AMS2, for example I find the LMP2 & the DPI the best of all Sims and the GTE feel very great, too.

 

I've done some calculations on my own. For a 1400 kg rally car, 4 m long and with a 50/50 weight distribution, a wheel has a diameter of 0.29 m, a mass of 20 kg, and is considered as a homogeneous solid disk. After a jump with an initial speed of 130 kph, the wheels will have an angular speed of 63 rad/s and will be located 0.5 m from the car's center of gravity along the vertical axis. Taking into account the positioning of the wheels relative to the center of gravity and the car's wheelbase, much of the force cancels out, so only a portion of the moment of inertia is transmitted.

I won't explain all my calculations since they mostly involve static torque analyses, but in the end, I found that the car would rotate between 2 and 5 degrees per second, which is not negligible but not enormous either, unlike in AMS2 where speeds can exceed 70 degrees per second for almost all cars.
So the inertia of the wheels is very exaggerated and as I said you can't control a vehicule when the front end is locked but can still in AMS2. They really need to patch the last one IMO cause this effect is present even you not locking the front so that's why the front end is always alive (I guess).

you literally confirmed what I wrote, if you lock both front wheels you don't get UNDERsteer as you said getting in AMS2, in reality you get NOsteer.
There is still a steering motion applied to the car from your wheel input, which is why you see a permanent oversteering effect at both the entry and exit of a turn. if the car understeers, it generally does so in the middle of the corner.

 

Yes he did, he also mentioned ACC and LMU accurately represent GT3 cars. If you drive the ones in ACC, they also snap but you can catch them relatively easily. I say "relatively" because what's easy for me may not be easy for someone else. Either way, ACC GT3 act like high downforce GT3 cars are believable, easy to drive and intuitive to catch when the rear snaps.

AMS2 sudden loss of traction and being totally not saveable doesn't feel realistic to me. I think I've mentioned this several times but cars don't drive like that on track IRL unless you go out on cold tires and try to drive 10/10ths. Once you warm up slick tires, you can really lean on them and play with slip angle as you enter, mid and exit corners.

 

New setup, but I tweak and build my own tunes. So personally tweaked tune I guess. The main thing I've noticed with V1.6 is when the longitudinal load shifts forward during trailbraking, the difference in grip transfer to the front of the car seems magnitudes much higher than what's available at the rear of the car. Which is probably what's causing this "snappy" rear behaviour.

Either way, it just feels unrealistic, especially in a front engine RWD car, where the natural tendency of the car tends to understeer. Under heavy braking, both static and dynamic load at the front of the car overwhelms the front tires of the car easily. But lighter braking can cause enough load to shift to the front, which actually increases front grip compared to rear and can cause instability.
Obviously setup can also affect that, but this isn't my 1st rodeo in both sim racing and IRL.

SCCA Time Trial event last year at a local track in Colorado. I ended 2 tenths behind the class winner and ended up 2nd.

 

Seems like the load sensitivity of the (rear, wider?) tires is high, causing instability on corner entry but allowing you to accelarate sooner as the load moves to the rear.