
A set of coilovers.
A 'coilover' is an
automobile suspension device, short for "coil (spring) over strut". It consists of a
shock absorber (British: damper) with a
coil spring encircling it. The shock absorber and spring are preassembled as a unit prior to installation, and are replaced as a unit when the shock absorber has leaked. This provides for optimal damping without torsional loads. Some coilovers are adjustable for
ride height and hardness as well using a simple threaded
spring perch similar to a
nut.
The coilover is a basic component of the
MacPherson strut suspension system, which is distinguished from other arrangements by employing a particular design of
anti-roll bar as a longitudinal constraint. This was the first widespread use of the coilover in automobile suspensions. But there are other designs; the word ''coilover'' should not be considered a synonym for the MacPherson strut arrangement.
Coilovers should not be confused with struts or independently mounted shock absorbers.