Sudden high speed instability

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Michael88

Michael88

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Has anyone else experienced strange sudden high speed instability with group-c and LMGTP cars?

Unless I increase down force at the rear by an ungodly amount making the car understeer a lot the cars become nearly uncontrollable at 190 mph, and that very abruptly. I just took the Jaguar XJR-9 for a spin at Le Mans and while it performed beautifully in the slower corners it was absolutely impossible to keep it on the track at Arnage, at the Porsche curves or keeping it in a straight line at the straights. Even with toe .20 and 600/700 downforce and ''tame'' differential settings it was impossible to control at high speed corners, on the straights and when breaking at the chicanes.

The strange thing is it happens abruptly, once the cars break 190 or so it feels like they become incredibly light at the rear.

I'm having this problem with the jaguar XJR-9 and the Bentley Speed-8, I'm using a wheel, no aids, chassis aren't worn.
 
Could it be the camber settings - that they work in reverse in gt6. I've set them to 0/0 & have had no issues.👍
 
I don't have a lot of running time of late, but I had a game session yesterday wherein my car was a bit more flighty on Sarthe. I qualify that by reminding all the Anni Viper does not have nor allow aero adj.
However, it's quite noticeable on that car when you go from taxi & runway rules to In Flight Rules.
💡:gtpflag:
 
Do you use a wheel? If so, what's you force feedback set to?

I know that in Gran Turismo 4 I couldn't turn down the FFB too much so driving cars fast (like 220mph+) was nearly impossible because it caused my wheel to go back and forth, spinning the car out. I had to turn ASM on.
 
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I'm aware of the stupid camber bug, all my cars have zero camber.

I set FFB to 9 because FFB feels weak compared to what we had in GT5.
 
I think that could be your problem then. Try setting FFB to like 4 or 5 and see if you still have the problem.
 
My cars used to do this because i never run max aero in the back but i do in the front. You could try increasing rear toe but the main problem was of course, the rear aerodynamics.
 
It's more noticeable with the Citroen GT Concept's, above a certain speed they start moving about on their own and if you go to correct it you'll more likely spin.
My solution only really works for Route X but if you put race tyres out back and sport or even comforts up front, the speed at which the car starts getting unstable will be higher.

For LeMans I can suggest tweaking the differential,suspension and downforce.
 
You're running zero camber and tame diff settings. You need a few more hundredths of toe in the rear as well. Tighten up the diff, add a little toe and stop running zero camber. It is not the best setting. I don't understand why people feel it to be. A tiny bit of camber will make the car more stable at the center of the apex. You'll burn tires out faster and overheat them easier, too. I run most of my cars around a half degree. Zero camber up front is going to make it twitchy as sin with most toe settings. And the rear will want to follow the front, of course. Things like nose dive, however slight in the LMPs, will lift weight off the rear. Trying stiffening up the compression settings on the front shocks as well. Spring rates should be pretty damn close to each other. They're all roughly 50-50 weight. A little negative toe is fine up front, but stay in the hundredths. Don't dip into the tenths.

They're not supposed to be easy to control. You need to learn to trail brake with these, too. It is imperative.
 
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Ive been testing and tuning the Toyota 7 recently and also had the problem of the car literally not being able to drive in a straight line at high speeds. What I found was the problem, and the solution was too low ride height given the massive downforce these cars generate at speed. The car was literally bottoming out the suspension above a certain speed. I raised the ride height untill the car began tracking in a straight line at speed and problem solved.
 
I've noticed in the gt6 tuning forum that the ride heights in the majority of tunes I've used are in the mid range - unlike in gt5 where lowering them seemed more beneficial. Very interesting.
 
Michael88
Has anyone else experienced strange sudden high speed instability with group-c and LMGTP cars?

Unless I increase down force at the rear by an ungodly amount making the car understeer a lot the cars become nearly uncontrollable at 190 mph, and that very abruptly. I just took the Jaguar XJR-9 for a spin at Le Mans and while it performed beautifully in the slower corners it was absolutely impossible to keep it on the track at Arnage, at the Porsche curves or keeping it in a straight line at the straights. Even with toe .20 and 600/700 downforce and ''tame'' differential settings it was impossible to control at high speed corners, on the straights and when breaking at the chicanes.

The strange thing is it happens abruptly, once the cars break 190 or so it feels like they become incredibly light at the rear.

I'm having this problem with the jaguar XJR-9 and the Bentley Speed-8, I'm using a wheel, no aids, chassis aren't worn.
Click to expand...

Sounds like you're bottoming out at speed, and, in your case, that the front is bottoming out first. Raise your ride height as high as possible. Then, bring each number down little by little until you start to feel some instability. At that point, increase your RH by 1 on the front and rear. Also, if your front ride height is a lot lower than the rear, then you will get oversteer at high speed (and understeer at low speed).
 

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