Suspension: Strut Assembly
Struts and shocks prevent unwanted spring motion by forcing hydraulic fluid through tiny holes in a piston located inside its chamber. It provides resistance to both its compression cycle and its extension cycle and prevents sudden movement isolating the chassis and passenger compartment from the irregular road surface. Without this dampening effect, the vehicle would feel like it's floating down the road.
A strut is a shock absorber and a coil spring combined. This system was designed by Earle S. MacPherson in 1947 and is now the most commonly used independent suspension found on vehicles today. A strut, like a shock absorber, prevents the coil from oscillating after it hits a bump in the road.
Typically when replacing struts, the coil spring is reused, and the shock absorber/spring seat portion is removed and replaced. A special tool is required to compress the spring. Most shops and dealerships have one mounted to the wall. If not, an inexpensive pair of strut spring compressors can be used to compress the spring. Be careful, safety first. Compressed coil springs contain a considerable amount of energy.
When removing a strut from a vehicle, be careful to check for any camber adjustments. If the strut has an eccentric camber bolt, mark its position before removal. Adjust both camber and toe when replacing this type of strut.