Quote:
Originally Posted by richard in NC
I've also learned to ease into the brakes a bit which helps, say the first 50 feet from 100 mph, and then hard on them. They also made some rear camber/toe adjustments that could help.
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I think this is the way to drive around the problem. I cannot say why this happens, but the idea that it's due to intervention from the car's safety measures is interesting.
Anecdotal evidence aside, I decided to look at some data from my Solo DL to see what it might tell me. There are 2 turns I've experienced this issue pretty strongly, one is T12 at COTA, the other is T15 at Eagle's Canyon Raceway. I decided to use data from ECR where I encountered the issue and then adapted to drive around it later in the day.
Braking at the left-hand T15 isn't what I would call complicated. I position the car track right and brake hard at or just after the #2 marker, and trail into the turn, so there really shouldn't be any steering movement
in theory. But what happens when you try and "kill the brakes" as my instructor said, is the car shifts inward what feels like a car's width and I would correct, trying to reposition the car back wide. I think you can see that in the data capture below (unfortunately I don't have video).
What's interesting about this screen capture is that it shows the
ASC activating and appearing to slow the rear-left wheel, but only deeper in the braking zone. Note that ABS is on through the majority of this heavy braking and that the Brake P F (front brake pressure) is not indicative of brake pedal pressure.
I'm still thinking about this, but I am beginning to think it's a combination of not enough spring/damping to control the rapid transfer of weight unloading the rear, and alignment/geometry. In that case, I think the ASC may just be exacerbating the issue, but not the root cause. I may be right or wrong (doesn't matter to me), I just enjoy investigating and learning from data.
My car setup- 275/35 18 square
- AP Racing 9668 front kit
- DS 3.12 pads
- Öhlins Road & Track @ 3 clicks from full stiff