Quote:
Originally Posted by ryude
Body roll is an indication of chassis rigidity, which does indicate handling performance.
Body roll means the chassis is flexing, which means the weight is transferring to one side, which means you have reduced traction on 2 of your wheels in a turn.
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Erm....no, sorry that's not right whatsoever.
Body roll is a function of the suspensions' roll center and the cumulative effect of all the force vectors acting upon the suspension as a result of a certain amount of lateral acceleration. A suspension can be designed to give anywhere between significant body roll, zero body roll, and negative body roll [the latter usually needing active components]. Actual chassis strength does play a role, but it is very marginal. For example, an R53 MINI Cooper body is claimed to be 50,000N/° [just a factoid I remember]. The same car has a front spring rate of 225 Lb/In. It's tough to make direct correlations, but compressing the suspension one inch equates to stressing the chassis just 7% the torque needed to flex the chassis 1 degree.
In this example,
no amount of available suspension travel will ever stress the body so it'll flex 1 degree.
Of course, in the real world, there's also anti-roll bars to add to the wheel rate, and people jumping their car off mountain tops or whatever and bottoming out the suspension. In reality, the chassis will get more abuse, but in modern cars with very stiff unibodies and monocoques, chassis flex is a virtual non-issue.