Why is body roll bad?

[mpg9999]

Im not much of a road race kinda guy, but I believe it's to keep the tires planted on the track and maintain traction. Body roll around a turn takes weight off the wheels. In Drag racing however, you want a bit of body roll..well, for RWD cars that is, to plant the rear tires and give you a bit of extra traction for better 60' times and whatnot

That is wrong. Don't feel bad though, its probably one of the most common misconceptions out there. Something about weight transfer is the answer I hear most of the time.

Blingmw, sure, there is most definatly a thing as not enough. However if we are talking about for max performance, the amount of body roll you want is very small. You want the smallest amount of body roll possibly while still being able to maintain contact over iregularities on the track surface.

Like Mike said, Scotty is on the right track with the geometry answer.