What a coilover actually is
A coilover is a matched spring + shock absorber in one unit, with ride-height adjustment built in. The good ones also let you adjust damping (how stiff the shock is). The bad ones are just a lowering spring bolted to a weak shock with a shiny paint job. Price alone doesn't tell you which is which — the details below do.
Spring rates: the number that decides everything
Spring rate (measured in kg/mm) is how stiff the spring is. Higher = flatter cornering but harsher ride. Street cars typically run 6–10k front / 4–8k rear depending on weight; track cars go higher. Red flag: a kit that won't tell you its spring rates. If the seller can't answer "what are the spring rates?", they didn't engineer anything — walk away.
Damping adjustment: what to actually look for
Single-adjustable (rebound + compression together) is plenty for 95% of drivers. Double-adjustable is for people who tune at the track. What matters more than the click count is whether the adjustment actually does something — on cheap kits, 32 clicks of adjustment might change almost nothing. Ask for a dyno plot if you're spending real money; a serious manufacturer has one.
Monotube vs twin-tube
Monotube shocks handle heat better and respond faster — better for performance driving. Twin-tube rides softer over small bumps and costs less — fine for a street car that just wants a drop. Neither is "better" in absolute terms; match it to how you drive.
Top mounts: don't skip this
The top mount connects the coilover to the car. Pillowball (spherical) mounts give sharper response and usually camber adjustment, but transmit more noise. Rubber OEM-style mounts stay quiet and comfortable. If your kit reuses your 100k-mile stock mounts, budget for new ones — worn mounts ruin new coilovers.
Cheap coilover red flags
- No published spring rates or damping specs. The #1 tell.
- Extreme drop claims ("lowers 4 inches!") with no mention of shock travel — bottoming out destroys shocks.
- No rebuild service. Quality coilovers can be rebuilt; disposable ones can't.
- Copy-paste listings with the same photos across ten "brands."
- Price too good to be true for a full set — corners were cut somewhere, usually in the shock internals you can't see.
After you buy: the setup matters more than the brand
Get an alignment immediately — lowering changes camber and toe, and bad toe eats tires in weeks, not months. Corner-balance if you're serious. And break them in gently for the first few hundred miles. Browse quality-checked suspension parts in our catalog, and confirm fitment against your year, model, and trim with the seller before ordering.