What Are Coilovers?
When first glancing through the Performance Coilover Kits section of our website, you may be put off by some of the prices you see. After all, what are you buying other than a combo set of springs and shocks under some fancy name? Certainly, you ask yourself, can’t you purchase springs and shocks separately and monetarily come out ahead?
Before you make that decision, read on to learn that sometimes, the whole is greater than the sum of the individual parts. Such is the case with coilovers. We’ll show you that they are more than “just springs and shocks”, and once the added value is recognized, the price actually becomes reasonable.
A coilover combines a coil spring and shock absorber into one integrated assembly. The coil spring is seated around a specially designed shock housing that mounts in place where OEM coil springs or MacPherson struts would be. Like any spring, coilovers serve to support the weight of a car or truck’s body. However, it’s important to note that even though a coilover’s housing plays an integral role in supporting vehicle weight the same way a strut does, coilovers are not technically struts. The reason for this is because coilovers are not structural suspension members, which struts are.
Coilovers are found on many vehicles, from RC cars to normal passenger cars, race cars and 4×4 vehicles. They are sometimes used as a factory suspension option on new cars. Coilovers are used in double wishbone suspension systems, and are often a component of MacPherson struts.
Two of the main types of coilovers are full coilovers and slip-on coilovers. Full coilovers are matched up with a shock absorber from the factory, while with slip-on coilovers, the dampers and springs are bought separately and then assembled.
There is a large number of companies who make aftermarket coilovers for vehicles, many of which allow the customer to adjust various settings such as ride height and damping. Camber and caster angles can also be adjusted if the car’s suspension allows, and if the coilovers are supplied with adjustable top mounts. This high degree of adjustment is what gives coilovers an advantage over typical MacPherson struts.
A coilover consists of a damper, with a coil spring encircling it. The damper and spring are assembled as a unit prior to installation, and are replaced as a unit when either of the sub-components fails.
Some coilovers are adjustable. Most, if not all, adjustable coilovers have variable ride height and preload, adjusted using a simple threaded spring perch similar to a nut. Alternatively, the damper’s threaded body is matched to a threaded bottom mount which allows ride height adjustment without affecting bump travel. Most coilovers also have adjustable dampers, which are usually adjusted with an adjustment knob on top of the damper. Stiffness can be changed by switching the spring for one with a different spring rate or by adjusting the stiffness of the damper.
Coilovers are made up of several components, including the damper, coil spring, bushing, bump stops, upper and lower mounts, various nuts and washers, threaded sleeves, and collars.
Thanks to built-in adjustability, coilovers offer the ability to be shortened or lengthened – lowering or raising the ride height of your vehicle through manual adjustment, without complex electronics or hydraulics. As they compress, ride quality becomes firmer and more buttoned-down without the harshness of shortened coil springs.
Methods used to change height vary according to design. Some use a threaded collar at the base of the spring, while others use a knob at the bottom to vary the length of the shock body. Thus, any corner of your vehicle can be dropped from factory ride height to a setting that’s up to 3 or 4 inches lower – reducing or eliminating the gap between the top of tires and fenders to create a desirable “flush stance”. This makes them an economical alternative to air suspension kits.
Most coilover kits include the wrench or similar tool needed to make adjustments, and almost all these kits allow the adjustments with the units mounted on the car.
Lower stance also lowers your vehicle’s center of gravity which, in turn, reduces body roll while improving cornering, braking and acceleration. And unlike traditional lowering coil springs that reduce ride height by a fixed, predetermined amount, coilovers can be fine-tuned to a different height at each wheel, especially useful when racing. That’s something air suspension kits can’t do.
Because coilovers are designed to provide height changes at a physical point that doesn’t reduce suspension travel so much, it’s easier to race or drive at a lowered ride height without you, your suspension components, and sensitive vehicle electronics taking a pounding. The value of coilovers is found in this greater level of adjustability.
If you prefer, there are coilovers that offer power adjustment for ride height. Like air springs, they’re designed to provide soft ride comfort at full extension and firm handling with minimal body roll when lowered. Compare these to the cost of air suspension systems, and you’ll find power coilovers still have a price advantage as well. Many coilovers are made largely out of aluminum, which removes unsprung weight from your vehicle. That’s worth a price, no matter what kind of driving you do.
Coilovers designed primarily for street use will come with pre-set rates for shock absorber compression and rebound, while those for more aggressive street use or racing will allow additional adjustments for each. A firmer compression setting means the piston inside the shock has greater resistance to moving downward and the ride will have less give. A firmer rebound setting translates to a shock absorber that will bounce back up less eagerly during its extension.
For example, on the drag strip, you want the front end of a rear-wheel-drive car to quickly rise on takeoff then slowly drop to ensure more weight stays over the drive wheels for grip. For best results, rebound (extension) would be set to soft, and compression would be set to firm.
With these types of coilovers, it’s easy to dial in the amount of firmness you need for hard cornering, then select more give when you’re loaded down with a carful of friends and gear on a road trip. The wrong rebound and compression settings can lead to an unnecessarily harsh ride, a reduced tire contact patch on the road, compromised grip, and the costly expense of accelerated tire wear. When wheels hop excessively from shocks that aren’t pressurized correctly for the ride or handling you want, you’re not getting the full benefits that adjustable coilovers offer.
Racing-oriented coilovers are designed with higher strength and heat reduction in mind. Inside the shock absorber, a “mono-tube” layout (see our related article on mono-tube vs. twin-tube shock designs) keeps hydraulic oil and nitrogen in separate chambers separated by a floating piston. As a result, there’s no aerating of fluid within the shock body and no wasted time adapting to irregular surfaces.
Some shock absorber elements are even mounted in an inverted position to position the hydraulic fluid chamber further away from brake rotor heat. To hold more fluid and maintain cooler operating temperatures, racing shock bodies are usually larger in diameter – or, they may be equipped with additional external fluid reservoirs. For heavy-duty strength that’s invaluable on racetracks, lower mounts on racing-oriented coilover may be crafted from steel rather than aluminum.
Coilovers For Street Driving
For those interested in improving handling and performance during street driving, Belltech’s Coilover Lowering Kit offers a choice of three different setups which feature manual height adjustability (choices will vary depending on make and model). For drivers who want performance and ride comfort but don’t want to manually adjust shock damping rates after changing the ride height, Variant 1 coilover take the worry and guesswork out of it. Pre-set by the factory, Variant 1 will automatically achieve an optimum balance between sport handling, comfort, and safety at any ride height.
Belltech Variant 2 coilover are designed for the more experienced drivers who prefer to set their own damper rebound rates when changing ride height. This set of four coilovers offer infinite adjustment of shock rebound damper rates to regulate vehicle pitch and roll behavior for ride comfort, rather than a fixed number of choices.
For the expert driver and tuner, Variant 3 coilover feature two-stage valves that allow an infinite level of rebound damping adjustment (comfort) and adjustable settings for compression adjustment (driving dynamics) in the low-speed range. Variant 3 settings for high-speed range (driving safety) are fixed. For the pickup truck owner who wishes to lower their vehicle in the front without giving up ride comfort or handling, Belltech also has a selection of coilover for 4x4s that allow 3″ of drop.
KW Suspensions also offers street-use Inox-Line Lowering Coilover in three basic variations. For simple, no-muss operation choose the V1 Inox coilovers with pre-set damper settings. V2 Inox coilovers add rebound adjustment, and V3 Inox coilovers also allow compression rates to be adjusted to regulate driving dynamics. For higher-speed highway driving and everyday comfort, there’s the KSport Kontrol Pro Coilover Kit (includes rebound and compression adjustment), KW Suspensions Street Comfort Coilover Lowering Kit (height and rebound adjustment), and Eibach’s Pro Street Lowering Coilover Kit (height adjustment only).
Automatic Ride Height Adjustment
KW Suspensions offers several street-use-only coilover kits that provide automatic ride height adjustment at the touch of a button. For vehicles already equipped with electronically activated dampening control, the DDC Coilover Lowering Kit (Dynamic Damping Control) features a soft-riding “comfort” mode, firmer “normal” mode, and “sport” mode with minimal body roll. If your vehicle came from the factory with an electronically adjustable suspension already, the “Plug & Play” kit provides just the coilover springs – as replacement parts or as an upgrade.
Wire connectors attached to each coilovers plug directly in and work with your vehicle’s existing wiring, factory control module, and interior switchgear. If your vehicle came with traditional coil springs and shocks and has no components of an electronically adjustable suspension system, an “ECU” kit will be included that provides everything needed to retrofit your vehicle.
KW’s Hydraulic Coilover Lift System is a set of 4 normally-functioning coilovers that feature an additional hydraulic cylinder unit mounted between the spring perch and spring. These expand to provide 1.8 inches of front and rear lift when lowered vehicles need extra clearance for speed bumps, shop lifts, and more. For vehicles already equipped with OEM electronically controlled leveling shocks or factory air springs, the conversion kit includes just the hardware needed to add KW coilovers.
Drag Racing & Short Duration Track Racing
Drag Version Coilover kits make it easy to transfer or keep vehicle weight over drive wheels where it will ensure the back end stays planted for a quicker launch. We’ve got the KONI Universal Drag Racing Coilovers and the KSport Drag Race Version Coilover Kit. For those who are involved in a more serious level of drag racing, Eibach’s Drag Launch Kit is a not a coilover kit, but a set of very stiff springs and adjustable air bladders that can be fitted to Eibach Multi-Pro-R1 Drag Launch coilover kits to virtually eliminate all body roll, squat, and dive.
Eibach’s Multi-Pro kits are designed for the modern car performance enthusiast who drives their racer on the street to work every day, then takes it to the track or drag strip on weekends. In Product Options, choose R1 series coilovers for street driving with a small amount of club racing, or R2 series coilovers for a more aggressive level of racetrack driving as well as street use.
There’s also the Bilstein B16 Series Coilover Kits – available for a wide range of makes and models. If you prefer an emphasis on shorter duration track use, consider the KSport GT Pro or the Bilstein Clubsport Series Lowering Coilover Kit. KSport also offers the Race Version Coilover Kit tuned to offer consistent performance during shorter races where fast, sudden speed and directional changes are the norm.
If you’ve got a Chevy Corvette C5 (or newer), aFe’s PFADT Series Featheright Single Adjustable Street and Track Coilover System is a coilover kit specifically designed to install in place of the Vette’s OEM transverse leaf springs and shocks. Once installed, you’ll see a more comfortable street ride without the harshness those leaf springs are known for, and you’ll see better performance on the track. These Featheright coil springs are also available for other makes and models in street/track and drag strip applications as well.
Extended Track Racing
If you’re planning on doing a more serious level of racing, KSport offers the Circuit Pro Coilover Kit with external fluid reservoirs to keep hydraulic fluid cool for steady, fade-free shock performance during long periods of endurance racing.
KSport offers the Rallye Spec Coilover Kit for optimum control over uneven dirt trails. In the Product Options fields, you can choose Asphalt Rally coilovers that allow ride height drops up to 3 inches for pavement, or Gravel Rally coilovers for ride height increases up to 2 inches for clearance on uneven trails.
While coilovers are thought of by many only as lowering devices, we also offer several kits designed to provide ride height lift for trucks. Skyjacker’s Platinum Coil-Over Lift Kit provides lift on all 4 wheels of your vehicle with coilovers for the front and replacement coil or leaf springs for the rear. Because this kit is set up for permanent height increase, front coilovers are not height adjustable, and twin-tube shock absorbers are designed with emphasis on maintaining stock ride comfort.
For those interested in more serious off-roading where pounding can cause normal shock absorbers to overheat and fade, the ReadyLIFT Fox Front Coilover Kit provides two coilovers for the front of your vehicle only. Unlike the Skyjacker kit, these are height adjustable from the vehicle’s stock ride height up to 3″ of lift. Built-in monotube shock absorbers enhance stability, and external hydraulic fluid reservoirs provide better endurance thanks to a larger amount of fluid that disperses heat more effectively.
As you can see in the picture below, it’s possible to enter the year, make, and model of your vehicle in the beginning of your search so that our website automatically does the work of narrowing down which coilover kits are offered for your specific car or truck. When looking through our selection, you’ll notice each kit features one main lead picture. These pictures are not fully indicative of all the variations you’ll find for each kit, because components vary from vehicle to vehicle. For example, a kit with a main picture of two coilovers may also be available as a set of four, and offer additional choices not shown.
Once you’ve gotten your coilovers installed, you’ll appreciate the high degree of customization you can literally dial into your suspension. Performance will be enhanced, and you’ll have features you never thought you could have for the amount of money spent. At this point, we trust we’ve convinced you that coilovers are great value for the money, and are really not “pricey” at all.