What Are Coilovers? The Complete Guide
You have seen them at car meets. You have watched the builds online. You have heard people at the track talk about which brand they run and what spring rate they picked. Now you want to know what coilovers are and what they actually do. And whether they make sense for your car.
What Are Coilovers? Understanding Coilover Suspension
A coilover combines a coil spring and a damper (shock absorber) into one unit. The spring wraps around the damper body. The assembly bolts between the chassis and the hub carrier or control arm. It carries the weight of the car and controls how each wheel moves over the road.
What sets a coilover apart from factory suspension is adjustability. With a coilover kit, you can raise or lower your ride height. Most kits also let you tune damping, and many let you swap springs. That is why a good coilover kit sits at the center of most performance suspension builds. Once you know what each part does, the appeal makes sense.
Components of Coilovers
Every coilover kit is built around the same core parts. Know what each piece does and you will understand what you are paying for.
Damper (Shock Absorber)
The damper is the heart of the coilover. It controls how fast the spring compresses and how fast it rebounds after a bump. Inside, a piston moves through oil and forces it through valves. That resistance turns spring motion into heat. Without it, the car would keep bouncing after every bump.
Coil Spring
The spring carries the weight of the car and soaks up road impacts. Its spring rate tells you how much force it takes to compress the spring by one unit of distance. You will see it listed in pounds per inch or kilograms per millimeter.
Threaded Body and Collars
This is what makes a coilover a coilover. The damper body is threaded, and so is the spring perch the spring sits on. On a full-length kit, a threaded lower mount sets ride height on its own. The spring perch then sets preload. On simpler perch-only designs, moving the perch changes ride height and preload together. A locking collar holds each adjustment once it is set.
Upper Mounts and Top Hats
These connect the coilover to your chassis. Rubber top mounts soak up noise and vibration and keep the cabin quiet. Pillowball mounts and camber plates locate the damper more precisely. Many add camber adjustment, but they pass more noise into the cabin. For a daily driver, rubber mounts are usually the right call. For a dedicated track car, pillowball mounts give you sharper control.
Bump Stop
The bump stop keeps the suspension from bottoming out under heavy compression. On a well set up coilover, you rarely touch it. When you do, you want it there.
Inner and Outer Cylinders (Twin-Tube Designs)
On twin-tube kits, the inner cylinder holds the piston and valving. The outer cylinder works as a reservoir for oil and a low-pressure gas charge. For a given body length, that layout usually leaves more room for stroke. Low gas pressure also puts less load on the seal and less force on the shaft.
How Coilovers Work
Common Coilover Adjustments
Car people love coilovers for the adjustability. Here is what you can actually change.
Ride Height. On a full-length kit, you thread the lower mount up or down the body to raise or lower the car. Drop it to lower the center of gravity and sharpen response. Raise it for clearance on rough roads or in winter. Every height change alters camber and toe, so plan an alignment.
Spring Preload. Preload is how far the spring is compressed with the wheel hanging and the car on stands. Once the car sits on its wheels, its weight compresses the spring far past that point. So preload does not change spring rate. It mainly keeps the spring seated when the wheel drops. On perch-only kits, it moves ride height too.
Damping. Single-adjustable coilovers give you one knob that moves compression and rebound together. Our guide to adjustable coilovers covers when that matters. Double-adjustable kits separate the two. You can tune how the car takes a bump apart from how it settles afterward. Click direction and click range differ by brand. Start from the kit's manual setting, then adjust a few clicks at a time.
Monotube vs. Twin-Tube
Monotube designs use one large tube, with oil and gas separated by a floating piston. The working oil touches the outer wall, so heat leaves quickly. That makes monotube the usual pick for track use.
Twin-tube designs run an inner and an outer tube. A well-built twin-tube still handles serious driving. For the full breakdown, see monotube vs twin tube designs. KW uses twin-tube dampers in its KW V1, KW V2 and KW V3 street kits.
Benefits of Using Coilovers
Adjustable Ride Height. You set it where you want it. Unlike lowering springs, you can change it any time.
Sharper Handling. A well set up coilover kit lowers the center of gravity, controls body roll and sharpens turn-in. You get more confidence near the limit. The difference between stock suspension and a dialed coilover setup is not subtle.
Corner Balancing. Each corner of the car adjusts on its own, so you can corner balance. The goal is about 50 percent cross (diagonal) weight. Set that way, the car handles the same turning left and right. Perches cannot change the front-to-rear split, though. Only moving mass does that.
Compact Packaging. The spring and damper share one assembly, so the package stays tight. Do not assume a coilover cuts unsprung weight, though. Unsprung weight is the mass the springs do not carry. That means the wheel, tire, hub, brakes, knuckle and part of the arms, damper and spring. It only drops if a part that moves with the wheel gets lighter.
Types of Coilovers Available
Full (True) Coilovers. These replace your factory struts or shocks with a matched spring and damper assembly. This is what we sell at Coilovers.com, in our range of full coilover kits. You get the full range of adjustment and a damper valved for the job.
Sleeve and Slip-On Coilovers. These slide over your existing factory shock. They cost less, but you keep the damping of your OEM shock. That shock was never valved for a lower car or stiffer springs. For real performance gains, go full coilover.
Non-Adjustable vs. Height-Adjustable vs. Fully Adjustable. Some kits have height adjustment with fixed damping. The Bilstein B14 PSS and TEIN Street Basis Z work that way. Others add adjustable damping, like the BC Racing BR Series with 30-click simultaneous compression and rebound. For most buyers, adjustable damping is worth having. You want to tune how the car feels, not just how it sits.
Spring Rates and Suspension Explained
When picking a coilover kit, spring rate is one of the specs you need to understand.
A higher spring rate gives a stiffer feel, less body roll and more feedback. That suits track days and hard driving.
A lower spring rate gives more compliance over rough roads and more comfort for daily use.
The trick is matching the rate to how you actually drive. A rate that works on a dedicated track car will punish you on a daily commute. A soft commuter rate can feel loose and vague on a circuit. Leverage matters too. Wheel rate equals spring rate times the motion ratio squared, so a low ratio makes a spring feel softer.
Adjustable dampers let you corner hard without getting beaten up on a rough highway. Match the damping to the spring. A stiff spring with soft damping feels floaty, and the reverse feels harsh.
Choosing the Right Coilovers for Your Car
Three questions decide most kit choices.
Use Case
How do you use the car? Daily driver, weekend canyon runs, track days, or all three? Your answer changes the right spring rate, damping range and top mount choice.
Brand and Price Point
Every brand we carry brings its own strengths. BC Racing's series ladder delivers feature parity with higher-priced brands at a value-performance price point. Swift Springs upgrades are available across most BC Racing fitments. KW brings German engineering, TÜV certification on most kits and OE programs with BMW M, Mercedes-AMG and Porsche. Fortune Auto hand-builds every kit in Virginia with custom valving. Öhlins brings racing pedigree, TTX twin-tube technology and DFV valving on Road & Track kits.
Platform
Fitment matters. Every brand engineers its kits differently for different platforms, and we know how each brand fits each chassis.
Installation and Maintenance Tips
Get a professional alignment after installation. This is not optional. Any change in ride height changes camber and toe. An alignment protects your tires and makes sure the car handles the way it should.
Torque everything to spec, from the top hat nuts to the lower mount bolts. Follow the kit's instructions for the locking collars.
Inspect regularly. Check the damper shaft for oil. A light film can be normal. Dripping is not, and it usually points to a worn seal. Confirm the locking collars have not loosened. Clean the threads every season. In salt-belt states, apply an aluminum-safe anti-seize before winter. Skip copper-based anti-seize near aluminum collars, because it promotes galvanic corrosion.
Dampers are wear items, so plan for rebuilds. Our coilover maintenance guide has the full routine. Each brand sets its own schedule. Fortune Auto publishes one for its kits. Street-only cars go 60,000 miles between rebuilds. Mixed street and track use calls for every 15,000 to 30,000 miles. Track-only cars rebuild every 1,000 miles. Check your kit's manual, or call 1-800-460-9106 and we will look it up.
Frequently Asked Questions
What are coilovers and how do they work?
Coilovers combine a damper and a coil spring into one adjustable unit. When your wheel hits a bump, the spring compresses to absorb it. The damper controls how fast the spring compresses and rebounds. Together, they let you control ride height, damping and spring choice.
Are coilovers the same as shocks?
Not quite. A shock, or damper, only controls motion. A coilover is a damper with a coil spring mounted around it, plus a threaded body for height adjustment. Every coilover contains a shock, but a plain shock carries no spring.
Which coilovers fit my car?
Each coilover kit is built for a specific chassis. Fitment depends on your year, make, model and drivetrain. Browse kits by your car below, or call us and we will confirm the right part number.
How do I choose the right coilovers for my car?
Start with how you use the car, your price point and whether comfort or response matters more. Then call us at 1-800-460-9106. A short conversation keeps a lot of people from buying the wrong kit.
How often should I maintain my coilovers?
Inspect them at every oil change and clean the threads every season. Rebuild intervals vary by brand. Fortune Auto lists 60,000 miles for street-only use and 15,000 to 30,000 miles for mixed use. Follow your own kit's manual.
Can coilovers improve handling on the track?
Yes. That is what they were built for. You get spring rate choice, adjustable damping, corner balancing and camber plates on many kits.
Do coilovers reduce unsprung weight?
Not automatically. Unsprung weight is the mass the springs do not carry, such as the wheel, tire, hub and brakes. A coilover only lowers it if the parts that move with the wheel get lighter. Lighter wheels, tires and brakes are the usual way to cut it.
Keep reading: Our guides to the coilover glossary and coilovers vs air suspension.
Ready to Find the Right Kit for Your Car?
You know what coilovers are and what they do. Now the question is which kit fits your car, your price point and how you drive.
We know these brands inside out: BC Racing, KW, Fortune Auto, Öhlins, Feal and TEIN. We know the platforms too. Call 1-800-460-9106 and tell us what you drive and what you want from it. We will point you at the right kit. No runaround, no upsell.
1-800-460-9106Browse Kits by Your Car
For a candid look at how coilovers are bought and sold online, see our guide on buying coilovers online.
Lou Tortola also shares a first-hand perspective in what coilovers are and who buys them.