Originally posted by Cole Trickle
As somebody else says, the bars harden the suspension, bu it feels differnt than using harder springs. One reason, is that bars ONLY affect side to side weight transfer, while springs affect BOTH side-to-side AND front/rear transfer.
Also, only use bars on smooth surfaces. On bumpy tracks, they can really mess things up.
Good point. With a properly set up sway bar (no binding), there should be almost no suspension stiffening for equal (right/left) loading (for example when the vehicle hits a little hump in the road.) When cornering, however, torque will transfer from the outside arm to the inside arm, effectively stiffening the inside suspension and relieving the outside one. The effect is to keep the chassis more level, reducing the weight transfer. Since the chassis will tilt less it will also reduce wheel camber changes and improve the tire contact patch.
The downside to a swaybar is that you've coupled the right and left suspension such that one side can not react without transferring load into the other. This a very small tradeoff on a smooth racetrack but is less acceptable for rough roads where you really want the tires to move independently and quickly. You would never want this, for example, on a rock crawling type vehicle.
There have been vehicles designed with sophisticated active suspensions that will allow any tire to move independently while at the same time reduce cornering roll. These work by changing the damping or spring rate of either suspension side based on measured cornering forces.