Quote:
Originally Posted by N Camarolina
Thank you for your thoughts Trakclub. I always appreciate your analysis.
I'm pretty certain it's not understeer (massive or otherwise). At my last track day two weeks ago at VIR I finally entered T1 with a few mph too many under trail braking, asked too much from the front tires, and had the car understeer. I simply opened the wheel a little (still under braking) so the ratio of lateral grip request was lower. Blew the racing line but easily, but had room to keep the car on the asphalt and kept the rear end planted.
Normally under trail braking with the extra weight on the front and the car and the speed in check, the front tires have extra grip and the car pivots amazingly well (on a dime in the best examples), and smoothly (not violently). But I also notice that I seem to sometimes get a little bit of extra pivot (yaw) when I release the last bit of brake pedal, near the apex. Normally it's fine and the back end stays under control behind me without ECS intervening. Every once in a while, though, this extra pivot winds up being too much for the rear traction and back end will start to step out.
The PDR data on PI Toolbox seems to suggest the extra yaw on brake release is more pronounced when the brake pedal is released (too) quickly. In the example where I had the back end step out while trail braking into turn 4, I released the last 18% of pedal considerably faster than what I had done up to that point and the yaw rate during that time climbed from 34% to 38% without any additional steering input, and this immediately preceded the rear losing traction. I would have thought that at that moment the weight transfer rearward would tend to stop any rotation immediately and perhaps initiate understeer, but clearly that's not what is happening.
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What you are describing seems completely opposite to what one would expect with a too fast a brake release UNLESS the rears are already at the limit and by moving weight to the rear (by releasing the brake quickly) you induce loss of traction there. Amd hence the slide. Assuming your ESC is working properly applying brakes to a correct wheel to reduce yaw, I would say you are waaay overdriving the car sir
And ESC let's you exceed limits until you exceed the ESC. Solution? Move up to PTM Race and assume direct control of yaw, based on what the car is ACTUALLY doing vs what ESC is preventing the car from doing due to your overdriving (meaning: you don't feel what the car is doing balance wise, as ESC is masking the exceeded limits, until its own corrective limits are exceeded).
I can tell you without a shadow of a doubt, that the car feels VERY different balance wise between Sport1 and Race. It is capable of very fast laps under BOTH settings, but it requires an adjustment from a driver. In my strictly personal opinion, the car is clearly safer in Sport1, but not necessarily easier to drive fast, as its feedback is muted by ESC (as one would fully expect). Hope this makes sense. Cheers and have fun!