Hi all. Before I ask my question, I thought I'd mention I do not road race (I autocross), I'm just asking because I like to know things.
I've read that the standard when setting a car up for racing is that one should tune roll stiffness with spring rates [or springs/shocks] and use swaybars for steer characteristics. My question is, why? What's wrong (or less good) with setting up roll stiffness with swaybars, allowing the racer to use softer springs? Common sense wise, it seems it would be better to have as soft a spring rate as one could get away with since most tracks do have bumps, imperfections, etc. Or am I missing something?
Thanks

 

Two reasons come to mind right off. With a heavy swaybar any single wheel movement is transferred to the wheel on the other side whether roll from cornering or just a bump. In a turn, body roll pushes up the outside wheels and the heavy bar will tend to lift the inside wheel too. With a light, or no bar, the outside takes the load and the inside stays on the ground.

The second reason is shock tuning. If the shocks are tuned to the spring rate and heavy bars are used, when cornering the shock rate will not be controlling the extra spring rate from the bar. A heavy bar is a very high spring rate in roll so the car ends up underdamped in corners. If the shocks are tuned for the heavy bars, then the car is overdamped when going straight.

Probably a bunch of other stuff I can't think of now.