The suspension system is what supports the car and provides for a smoother ride. A combination of springs and hydraulics it is what accommodates the ride of your car or truck. Your tires contribute to your ride as does the springs and shock absorbers. The MacPherson Strut combines the springs and the shocks into one unit. It makes for a very compact system popular on front wheel drive compact cars.
Signs of Suspension Damage
Some of the things to watch for in a worn suspension are: Excessive bouncing, Loss of contact with the road, Excessive or uneven wear of the tires, a decrease in the handling or braking of the vehicle, vibration or noise from underneath the car, leaking shock absorbers. Fluid around the shocks is never a good thing. Dents, holes or other damage to the shocks or struts.
For conventional suspension the primary wear points are the shock absorbers and the bushings. Most bushings are usually polyurethane bonded to steel liners or round cylinders of polyurethane for mounting with bolts and clips. The bushings isolate the suspension from the passenger compartment giving a more pleasurable ride. Excessive play due to worn joints and bushings affect the level of control over the vehicle while driving. As bushing where it also affects the steering geometry leading to control issues and/or uneven tire wear.
It is therefore important to consider the following:
Poor wheel alignment: Toe-in, camber and castor are all-important front-end steering specifications and relate the cars handling and front tire wear. It you live in a region where street and road maintenance in marginal your encounters with potholes and curbs will eventually affect the front steering specification and not in a positive way. Your alignment depends on springs and good tight bushings that hold everything together and that work in harmony.
Shock absorbers: shock absorber are suspension dampers. As your tires move across the road the springs try to make up for uneven roads. Harmonic, or repeated motions can build until the tire lose proper road contact by staying in the air or moving out of sync with the terrain. Shock absorber dampen the harmonic movements and not allowing the suspension system to get out of sync with road conditions. To keep the tires firmly in contact with the road shocks use fluid working through valves to dampen motion. If you are experience excessive bounce you may need to replace your shock absorbers.
Struts: Some vehicles use struts, units that combine the suspension springs and the shocks in one unit. A knocking sound when going over bumps is a common sign of worn struts.
Springs: Carry the load of the vehicle. Though not common in regular road driving, springs have been known to break. However, over time they can sag, lose their springiness. If you are on level ground and a corner is lower than the rest, you may have a problem with a spring. As springs carry the weight, if they fail, they can adversely affect driving control.
Ball Joints These are what hold all the front end and steering parts together. As they wear control can become iffy. If they fail it can be catastrophic. Along with the main ball joints there are steering joints that are subject to wear. You will want them checked as well.
Control arms; These do just what you would expect. They control the steering of the vehicle, bent, damaged arm connected by damage joints will adversely affect your control and steering as well as the alignment.