Sorry, I've downloaded so many mods lately I've lost track. But I went to Le Mans to test the fix for AI passing in the new Release Candidate and I saw several LMP1 cars dragging when ever they got up to a certain speed. Dragging in corners I understand as the weight shifts...but full on twin rockets of glory sparking out behind the cars like the Rebellion R1. The Ginetta. Strangely, the Toyota seemed fine. Even some LMP2 cars that had Global Endurance Mod on the sidepod. All the S397 content did not display this. I had chosen an AI race and used LMP1, LMP2 & GTE as the car choices so it was a mixture of S397 & 3rd party. Here is a sample, happens...perhaps as soon as 3rd gear is reached, even on short straights. This will continue down the entire length of the straight.
Keep in mind that, the higher the Speed, the higher the produced Downforce. Maybe you just have to use stiffer Springs for Example, to avoid that the Car touches the Ground and you just notice it now, because Sparks work again. Create a new basic Setup and assign it to the AI, to check if that solves it.
That was the solution I used for the S397 Oreca 07 when it would drag at high speeds. But this was something we saw when the new spark routine was introduced and most modders quickly corrected the problem. I did mis-identify one car, the Ginetta is fine it's the Russian LMP1,(BR1?) that is dragging. So Toyota & Ginetta ok, others...not so much. Later today I'll see if I can get a complete list of which cars this is affecting.
Unfortunately, to fix the problem it’s not enough in most of cases to make higher the car, or stiffer the springs. This because, first of all, changing setup is often counterproductive for the aerodynamics of the car, and in most cases it’s not completely resolutive. Then, this “bug” is more evident on AI cars. Therefore, sometimes human driver with a custom setup may alleviate the problem, which however remains on the cars of AI drivers. Infact, AI drivers are using a simpler HDV configuration and TBC tires, not always with the same diameter of tgm tires. The real solution is to recalculate the height of car respect to the real tire diameter ( TGM and TBC ) and the lowest part of the car (the bottom). Even the height of HDV undertrays must be considered. Actually, the only tool to do this is ( for me ) Borda sheet. Sparklings introduced by S 397 are a sort of of "signal" to understand if the car physics is well done or not. Ideally, it should be useful a game option to activate, or not ( with a range ) this feature. But, in my opinion, it should be only a fake solution, hiding the problem that remains. On the other hand, this new feature has increased realism (when present on cars that actually generate sparks….and nowadays even F1 cars are causing them very few). The funny thing is that even several S 397 official cars are suffering from this problem… a sign that even the S 397 Team didn't expect it and in so evident way.
