Quote:
Originally Posted by ovekvam
With AWD (and FWD) cars, it is impossible to add power without using less front wheel grip for transverse forces. That means you get understeer and a wider line once you start using the throttle in a corner. Some grip is lost in the front due to weight transfer, and even more because you are using it for forward traction.
|
Ovekwam, You did a really nice write up until this part... There is a transversal vector, which is orthogonal to the length ax of the car, and a longitudinal vector in the length of the car. the front tires on a RWD car leave the longitudinal vector rather unexploited. The AWD version will exploit it by pushing torque on the front tires.
When you check what the tire is going to do, you have to vectorial combine the longitudinal and transversal components together. When the combined forces exceed the grip of the tire, it slides.
When you check the grip "oval" of a front tire, you'll see that max g's are exploited when you combine transversal and longitudinal components. Assume theoretical that limits transversal and longitudinal are the same (they aren't since longitudinal are better, but anyway), you could converse 1.4142 times the transversal force to the FWD.
I agree that the transversal component will be a bit smaller on AWD, but the longitudinal one is clearly bigger. The overall G force on the AWD will be bigger during all circumstances. This will convert the AWD to a winner during circuit driving conditions while providing a comfort of mind to the one's not trying to set lap records.
Oh yeah, I brought it up... an xDrive AT will certainly lap faster on the Nordschleiffe than the RWD AT. Certainly with less swet involved, agree on that. But when you state, the max attainable lateral g's are best on the RWD, I agree but the difference is really small (about 1 percent) and not compensating enough for the lack of traction.