Swaybars (more accurately described as anti-roll bars) work by combining the coil spring rates of the two sides of the suspension that the bar connects (i.e. front left/right or rear left/right). For example, when a car turns, centrifugal force causes the suspension to move on its pivot points and the body to lean outwards. Without a bar installed, this leaves only the outside coil springs to fight body roll. When a bar is added, it rotates in its bushings and partially compresses the inside coil springs. This increases total roll resistance which keeps the tires flatter on the ground for more traction!
Unlike with race cars, OEM swaybar bushings are made soft and sacrifice control for comfort. The mushy material deflects easily and thusly reduces the amount of inner spring compression. Body roll is less controlled than it otherwise would be. More importantly, the rubber gets moderately stiffer as it compresses. This variability is absolutely maddening to the experienced driver who demands linearity in roll resistance.
All these Powerflex urethane replacements will improve performance, prolong tire life, and bring back the big go-kart feel!
Note: USRT generally recommends stock (or no) front bar for rally cars, moderately larger pieces for the street, huge front bars for autocross, and nothing up front in road racing applications. We'll be happy to explain why, if you ask.
These bushings are sold in the required number for one car for the specified location. (3)
