In a message dated 7/20/2006 5:59:57 P.M. Pacific Standard Time,
nihal@berkeley.edu writes:
I don't think that it would work this way. If the rear roll center is
lower, this does not change the total weight transfer at that axle. It
only changes the roll angle. The roll angle is purley a function of the
distance between the RC and cg height (the lever arm you speak of) and the
lateral acceleration. With the lower rear roll center the car will become
"lazy" and be more stable at that end.
The overloading of a tire doesn't make senes to me. The weight that went
onto that tire had to come off of another wheel (usually inside). These
inside wheels are what govern the oversteer and understeer characteristics
of a car. I would suspect if the front outside was in the situation you
describe (kind of like overdriving a FWD car) the front inside wheel has
very little weight, and thus cannot produce the lateral accelration it
needs to, and therefore you have understeer.
Okay, say it however you want to. My experience is with strut front/solid
axle rear cars. I know the following to be true.
1) MacPherson strut suspensions have a very low roll center, usually
between 2" above ground and somewhere below ground.
2) Solid axles without a Panhard or Watts have a roll center that is right
through the center of the axle. So, on a car with 24" tall tires, this is
12".
3) That's a steep roll axis and the car will push. Lowering the rear roll
center to say 6" above ground causes the rear to rotate more and the car to
push less.
this has been proven time and time again in numerous autocross cars. Cloak
it in whatever math or verbage you want to, but the end result is #3.
Charlie
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