cRedrum

whats the difference between shocks and struts ?

Daniel B. Martin

Shocks and struts are similar but not identical. "Strut" is short for MacPherson strut, named for its inventor, Earl S. MacPherson (a Ford engineer). A strut combines a shock absorber and a component of the suspension. This design is lighter and less expensive than some more sophisticated suspension designs which use upper and lower control arms or a multi-link apparatus.

Shock absorber is a misnomer because it does not really absorb physical shocks. The springs do that. The shock absorber prevents the spring from oscillating after the spring absorbs the shock of a bump in the road.

One way to appreciate the difference between a shock and a strut is this. You could remove the shock absorbers from a car and still drive it. You wouldn't want to, but you could. However, if you removed the struts from a car you couldn't drive it. The struts are part of what connects the wheels to the body of the car.

vmok

sometimes, people use the term shocks and struts interchangeably, and don't really know which they are referring to or refer to anything that dampens suspension movement as shocks. both are used to control the energy of the spring as Dan has noted, but are used in different applications.

typically, cars that use a struts (or strut type suspension) share the pickup point for the strut and spring assembly in the uppermount, with the strut residing within the spring and the lower mount of the spring residing on a collar of the strut body. however, non-strut type suspensions typically have their spring and shock assemblies separate (i.e., trucks typically have leaf springs with separate shocks, or many trucks have have coil springs separate from the shocks). macphearson struts share a common mounting point for the strut, spring, upper pickup point of the suspension.

the advantage of strut type suspensions over control arm suspensions is that in packaging efficency (save space), and requiring less peices, thus making it less expensive. control arm suspensions have more pieces, but more tuneability. by allowing the engineers freedom to choose where the upper and lower control arms is located, they can greater refine and control the movement of the wheel throughout it's travel.

as a note, the new honda civic's switched from double wishbone front suspension(upper/lower control arm) to a strut type (honda claims that it allows them to have a lower hoodline, but i think it's really cost savings!)

-V

btw, when you buy and install koni's, you're not changing the physical strut assembly, but the insert or cartridge, which containts the pieces that do the dampening.