If your car's suspension is sounding a lot like your knees -- creaky and popping -- it might be time to replace your suspension bushings.
Suspension bushings are rubber or synthetic shock absorbing disks, positioned at several points between your car's suspension and the vehicle frame. Bushings provide flexibility between moving parts while maintaining a degree of stiffness and therefore control. They buffer the vehicle against road vibration and noise, preventing excessive wear on the more expensive parts of the suspension system.
Bushings can be made from soft rubber compounds or very rigid synthetics, such as polyurethane. Polyurethane is preferable because it's not affected by temperature or corrosives. It won't become brittle and noisy in cold weather or melt if the bushing is positioned, for example, close to the exhaust. Unlike rubber, polyurethane won't deteriorate from the corrosive chemicals used on roads, such as salt, or from oils that the bushing might be exposed to on the car frame.
Erratic or loose steering can result from rubber bushings becoming too soft and flexing too much. Creaks, pops, knocks and excessive road noise inside the car might be the result of the car frame moving around too much when the bushing is no longer providing adequate cushioning.
