An adjustable suspension system combining the coil spring and damper into one unit, with adjustable height and damping rate.
Coilovers are an adjustable suspension system combining the coil spring and shock absorber (damper) into a single integrated unit. The system allows owners to adjust ride height (by changing spring perch position), spring rate (by replacing the coil spring), and damping rate (through external adjusters on the damper body). Coilovers replace the factory spring and damper with a more capable, adjustable alternative.
Quality coilovers offer several advantages over factory springs and dampers: adjustable height for stance or track use, stiffer spring rates for performance applications, adjustable damping for changing road and driving conditions, and longer service life. The trade-off is cost (a quality set of coilovers costs $1,500-$3,000 plus installation) and ride harshness (stiffer springs reduce comfort over rough roads).
Major coilover manufacturers include KW Suspension (German, top-tier), Ohlins (Swedish, racing-focused), Bilstein (German, often factory supplier and aftermarket), Tein (Japanese, popular for street use), HKS (Japanese, performance-focused), and Bilstein (German, mid-range). Quality varies significantly by tier; budget coilovers ($300-$800) typically have shorter life and inferior dampers.