Sway bars are also known as stabiliser bars or anti-sway bars, and they help suppress spring oscillations and reduce body roll, or sway. Sway bars balance the movements of independent suspension components through turns and over rough road surfaces. A sway bar also deflects lateral movement when installed on a solid rear axle. Proper sway bar performance will aid ride comfort and enhance handling characteristics.
Tire Tread Wear
A sway bar is a durable steel spring that transfers suspension action. The spring rate, or stiffness, of a sway bar remains constant unless damaged or fatigued by extreme age or overloading. A damaged or defective sway bar can exhibit tire wear patterns usually associated with high speed cornering. This tread wear appears as scuffing of the outside shoulder of the tire and crests in the tread. Such wear exhibited in the absence of high speed cornering can indicate sway bar malfunction.
Some sway bars are linked to the suspension and frame by linkage rods. The linkage rods have bushings at both ends to cushion the load transfer. Alternate styles are inserted into bushings in the control arm. Bushing failure of either style will result in erratic handling accompanied by a "clunk" noise in turns. Linkage-style bushing failure will also make a "jingle" noise over slight road bumps.
Lack of Control
The attaching points for the sway bar to the frame are commonly fitted with bushings that provide some cushioning while maintaining a firm grip. Gradual softening and wear of these bushings is normal over time and may escape notice on daily commutes. Demanding road conditions or driving habits, however, will reveal worn or soft bushings by a lack of precise control. Total failures result in displacement or complete loss of the bushing and are readily apparent by loud rapping noises in turns and erratic handling.
Excessive body roll or sloppy steering response in turns should be corrected. The actual sway bar is resilient spring steel and is rarely the culprit. Replacement kits for sway bar bushings or linkage assemblies are inexpensive and usually all that is necessary to restore original performance. Demanding motorists might choose neoprene bushings that are stiffer and resist wear better than stock rubber bushings. Intense enthusiasts may opt for stronger, thicker sway bars selected from aftermarket suppliers.