The Ultimate Guide to Coilovers. We’ve recently found ourselves writing an increasing number of suspension upgrade guides. Coilovers are a major topic because they are a popular upgrade option. However, there is almost too much information to cover in a single article. It’s a lengthy subject that can be confusing and overwhelming at times. What exactly are coilovers? What distinguishes them from struts and shocks? What is the difference between springs, lowering springs, and spring rates? What about twin-tube vs. monotube suspension, damping adjustments, and other considerations?
Again, there is a lot to cover, and it may appear overwhelming at first. But don’t worry. In this guide, we’ll answer all of these questions and more as we go over coilovers, struts, shocks, and springs.
What Exactly Are Coilovers?
In this article, we try to start with the basics and work our way up to more in-depth topics. Finally, we’ll go over some of the best and most popular coilover kits on the market. So, to begin with, what exactly are coilovers?
The term coilover is derived from the phrase coil over spring. It’s simply a type of suspension that allows for changes to ride height, camber, damping, and other parameters. To better understand coilovers, let’s first look at the differences between traditional shocks and struts.
Shocks versus Struts versus Coilovers
It’s not always easy to put everything into words. As a result, the video above is a good starting point for understanding shocks, struts, and coils. We like the above video because it is brief and easy to understand. Let us expand a little more on the main points.
The shock absorber is at the heart of all of these suspension components (shock for short). A shock is a hydraulic pump that dampens impact and rebound movements by using fluid and/or gas. This is what keeps the tires planted to the road and allows for a smooth ride.
Then there are struts. A strut is a shock absorber with a coil spring collar attached. The coil springs are then wrapped around the shock absorber and mounted on the shock. Struts are sometimes referred to as coilovers, which isn’t entirely incorrect.
A coilover is similar to a strut, but there is one significant difference. The shock body is threaded or grooved in multiple places. This allows the coil spring collar on the shock to move up and down, effectively changing the vehicle’s ride height. In other words, a coilover is similar to a strut but allows you to adjust the ride height.
Adjustable camber and damping are two other features that are common in coilovers. More on those subjects later. For the time being, let’s tie this all together by talking about coil springs.
What Exactly Are Coil Springs?
Coil springs were mentioned several times in the previous section because they are an important component of struts and coilovers. A coil spring is still used in a vehicle with a shock absorber, but it is mounted separately. When referring to struts or coilovers, the coil spring is mounted on the shock absorber.
In any case, coil springs are possibly the most important component of a suspension setup. The springs, not the shocks, support the entire weight of the vehicle. Coil springs support the vehicle’s ride height, keep it aligned, and absorb shocks and impacts. While cornering, accelerating, and braking, springs also control body roll.
Because they support the vehicle’s weight, springs absorb more impact than shocks. Shocks essentially assist in returning the springs to their natural position. If the vehicle didn’t have shocks, the coil springs would continue to bounce, so the shock dampens those movements. Springs will be discussed in greater detail later.
What Are Coilovers Used For?
Coilovers function just like any other suspension system. They assist in dampening impacts, supporting the vehicle’s weight, keeping the tires in contact with the road, controlling body roll, and other functions. It does the same thing as any other car’s suspension, whether it’s a shock, strut, or coilover.
So, what makes coilovers so unique? Again, the adjustable ride height is the deciding factor. Damping and other adjustments are common with coilovers, but these features can also be found in traditional shocks or struts.
The Advantages of Coilover Kits
Now that we’ve covered the fundamentals, let’s look at the advantages of coilover upgrades. Coilovers provide a lot of versatility and options. It doesn’t have to be all about lowering or extreme handling. The following are some of the advantages of coilover kits:
- Ride height can be adjusted
- Damping can be adjusted.
- Improve your handling, braking, and acceleration.
- Improved ride comfort and quality
- Replace worn-out suspension components.
All of these advantages are unlikely to be obtained from a single set of coilovers. Aggressive setups designed for track use and handling are frequently stiffer. This will reduce ride quality and comfort, but it doesn’t have to be significant. This is especially true when a good setup and adjustable coilovers are used.
They’re also an excellent upgrade for lowering, which improves center of gravity. Some people prefer coilovers for stance and slamming their car to the ground. Others are content with a simple setup that is adequate for day-to-day street driving. The point is that there are numerous options.
Whatever your interest in coilovers, it is critical to understand your objectives and budget. For the best results, different coilover kits are often required for different goals and uses. As a result, the rest of this article will go into greater detail about what to look for in coilovers upgrades.
Lowering Springs vs. Coilovers
Many people choose to lower their car by upgrading coilovers. Lowering springs, on the other hand, are a popular option for simply lowering ride height. Using only springs is the most cost-effective option. However, there are some significant disadvantages to using lowering springs. These are some examples:
- No ride height adjustment
- More rapid shock wear
Lowering springs allow you to select the springs that will give you the desired height. If you want to raise or lower the car even more, you’ll need a completely new set of springs. As with coilovers, adjustments cannot be made in minutes. Springs by themselves can also increase shock wear, implying that you may need new shocks anyway.
Finally, we believe coilovers are the superior option. This is especially true because lowering springs usually does not result in significant improvements in handling (without also addressing shocks). If you don’t care about handling and just want to lower or stance your car, you can find some very reasonably priced coilovers.
How Much Do Spring Rates Cost?
When it comes to coilovers or lowering springs, spring rate is one of the most important considerations. Spring rates are stated in two ways:
- kg/mm (or K for short) (or K for short)
A spring, for example, might have a rate of 400 lbs/in. This means that it takes 400 pounds of force to compress the spring 1 inch, 800 pounds to compress it 2 inches, and so on. The metric system uses kg/mm, and 1kg/mm equals roughly 56 lbs/in. As a result, a 400-pound spring equals 7.15 kg/mm or 7.15K. They are frequently referred to simply as K.
When spring rates are expressed in this way, they are consistent with a linear spring. Progressive springs, on the other hand, are a popular coil spring design.
Spring Rates: Progressive vs. Linear
The spring rates of a progressive coil spring vary. The spring on the right side of this image is linear. As we discussed in the previous section, the spring rate is always the same due to the linear design.
The spring on the left of the image, on the other hand, is a progressive rate spring. Depending on how far it is compressed, it will have different spring rates. The general idea is to have a softer spring rate for everyday street use that stiffens up when compressed.
There’s nothing wrong with a progressive spring if you want a simple setup or stance. They have the potential to provide a good overall balance. Progressive rate coils, on the other hand, can be difficult to match with the appropriate shocks. They’re also not ideal for handling, so those seeking better handling should look into linear rate coil springs.
The Value of Spring Rates
There is no one-size-fits-all solution for the best spring rates for each vehicle or setup. At least not without extensive testing, which the general public is unlikely to have the time or resources for. It’s usually best to let the manufacturer of the springs or coilovers choose the appropriate spring rates. Some also provide multiple spring rate options and can assist you in determining the best rates for your specific goals and needs.
In any case, there are a few general guidelines to follow here. A stiffer spring results from a higher spring rate. Stiffer springs reduce body roll and weight transfer, which is generally beneficial to handling. That is not to say that stiffer is always better. Stiff springs work well on smooth surfaces, such as a racetrack. Going too stiff on public roads with bumps and imperfections can actually make handling worse.
Otherwise, if you want to significantly lower your car, you’ll need stiffer springs. This will help keep the shocks from bottoming out on the bump stops, as well as the car in general from bottoming out.
What To Look For When Purchasing Suspension Upgrades
Okay, now that the springs are out of the way, let’s get back to the shocks. Coilovers provide a lot of potential adjustability in this situation. The shock design is an important topic to discuss before making adjustments.
Shocks: Twin-Tube vs. Monotube
Remember that the shock is essentially a hydraulic pump that dampens compression and rebound with gas and/or fluid. There are two cylinders in a twin-tube shock. The main cylinder, also known as the inner or working cylinder, houses the piston. The second cylinder serves as a reservoir for hydraulic fluid or gas.
Monotube shocks have a single cylinder. There is a fluid portion and a gas portion, and the piston moves within the fluid portion. We could spend some time dissecting how both of these shocks work, but that could be a separate article.
Instead, consider how they differ in terms of comfort and performance. Monotube shocks provide the most responsiveness, damping, and ride quality. Because they are more expensive than twin-tube shocks, monotube shocks are not for everyone. Twin-tube shocks are still a good option, but if you value handling the most, you should look into monotube options.
Damping Adjustments for Coilovers
There are three main types of adjustability that can be found on shocks. Pre-set by the manufacturer, single or double adjustable. There are no actual adjustments available with the pre-set. Instead, you must rely on the coilovers manufacturer to adjust the compression and rebound damping. Most will aim for a balance of performance and street comfort.
However, if you want the best handling and street setup, adjustable wheels are the way to go. This enables you to stiffen the shocks for use on the track or aggressive driving. You can return to softer settings for everyday street use in a matter of minutes. It combines the best of both worlds.
The common options are single and double adjustable. Single adjustable may only control either compression or rebound damping. It may also control both forms of damping, but you can only adjust them together. Double adjustable allows for independent control over both.
Ride Height Adjustments
Last up is ride height adjustment, and this is a pretty straight-forward topic. Keep an eye on different coilovers and what ride height ranges they allow for. Some kits may meet your lowering goals while others will not.
We find most standard coilovers kits allow for about 1-2.5″ of height adjustability. It can vary a lot from kit to kit and car to car, though. Some coilovers are also designed more for stance and may allow drops of 3-4+”. When it comes to high-end performance coilovers for handling and track-use the lowering ranges are usually less drastic. They may only offer lowering of about 0.5-2″.
Best Coilovers Upgrade Kits
Not to stray off topic, but we must admit we went a bit further than intended on the above topics. Even then, there’s a lot of specific info and technical detail we skipped over. In the future, we’ll likely break down these topics in greater depth if there’s any interest.
For now, let’s move onto some of the best coilovers around. Keep in mind – this is far from an exhaustive list and lot’s of great coilovers exist. We’re sticking to a few of our favorites for different budgets and goals that are available for a large number of makes and models
1) Coilover Kits from Raceland
Entry-Middle Level Street & Stance
Lowering: 1 to 4 inches
Most of the time, No (a few kits are adjustable)
Raceland is a contentious organization. Because they’re so inexpensive, some people assume they’re not high-quality coilovers. However, many customers are extremely pleased with their Raceland coilover experiences. To be clear, these are basic street and stance coilovers. They will not be the most maneuverable or comfortable options available. Raceland products, on the other hand, do exactly what they’re supposed to do.
They’re high-quality entry-level coilovers at an almost unbeatable price. Raceland provides excellent customer service and has very low return rates due to the high quality and service. At this price, that’s about all you can ask for, and Raceland delivers on all counts.
The majority of their offerings include their Classis and Ultimo coilover kits, which offer 1-3′′ and 2-4′′ lowering, respectively. They’re not adjustable and don’t come with top-hats, camber plates, or anything else. That’s fairly typical for a coilover upgrade in the $400-550 range. Monotube, adjustable, and other options are available for some makes and models for around $600-750.
Finally, Raceland is ideal for a minor street upgrade, lowering or stance, or simply replacing old suspension. If you prioritize handling over everything else, there are better options available (albeit more expensive options). That has nothing to do with Raceland; it’s just not their market. They make high-quality entry-level coilovers and do it very well.
2) Coilovers by BC Racing
Mid-High Level Street, Stance, and Track
Lowering: 1-3′′ or more
Yes, it is adjustable.
Price: ~$1,030 – 3,000+
BC Racing is another popular coilover option. The majority, if not all, of their kits are adjustable and provide incredible customization options. They have Extreme Low coilovers, you can choose between their springs and swift springs, you can customize your spring rates, and so on. The BR-series coilovers are their most affordable option, with prices starting around $1,030. Even these are adjustable, with front camber plates and optional rear camber plates when applicable.
You can then progress to their top-of-the-line kits, which can cost $3,000 or more. They also have a plethora of options in between. The point is that BC Racing has a large selection of coilover kits with extensive customization. Their BR-series is very popular because it provides excellent performance and features for the price.
There are few kits on the market that provide as many options and customization as BC Racing. That alone qualifies them for a spot on our list of the best coilovers. Add to that the fact that they are high-quality coilovers with extensive testing and proven results. If it all sounds too good to be true, it probably is.
3) Upgrades to KW Coilovers
Mid-High Level Street and Track
Lowering range: 0.5-2.5′′
Adjustable: Some kits are.
Price: ~$1,000 – 5,000+
Where to begin with KW? If you’re familiar with coilovers, you’ve probably heard of KW. They’ve been in business since 1992 and offer excellent kits for a wide range of makes and models. At the Nürburgring, KW coilovers have won a variety of 24 hour races. These guys know what they’re doing and make some fantastic high-performance coilovers.
However, they also provide a variety of street-friendly options, as well as street & track and track-use kits. Begin with their Street Comfort kits, which typically start around $1,000 to $1,200. The KW V1 is the next model, and it is not adjustable.
There’s also the KW V3, clubsport, competition, and more. They have it all, from mild to wild, and each of them produces top-tier results in their class. Yes, you pay a premium for their brand name and image, as well as high quality, proven results. However, KW delivers everything and then some when it comes to truly excellent coilovers.