Coilovers ultimate guide: learn all about the best suspension mod

Coilovers are a popular choice for car enthusiasts seeking to enhance their car’s performance and customization options.

By understanding how coilovers work and the various features they offer, you can make informed decisions when it comes to making a purchase.

In this article we go over what coilovers are, how they work, the different options you can choose from, and much more.

coilovers

What are coilovers

Coilovers are an advanced but simple suspension system made up of two major components. A coil spring and a shock absorber.

The coil spring sits over the shock absorber hence the name “Coilover”.

They are a very popular modification among car enthusiasts. This is due to their high adjustability and amazing performance enhancement. 

What does a coilover system do

Coilovers work like any other shock absorber and spring suspension system. However, the coil spring is over the shock absorber.

The spring determines the height at which your car sits. (ride height) The spring is also what brings your car back to this height after hitting a bump. Additionally, the spring is responsible for how “stiff” your suspension is.

In other words, how much your suspension compresses when you take a turn, accelerate or brake.

The shock absorber is really the main component of this type of system. It is responsible for absorbing all the shocks from the bumps, and potholes you go over. It is also responsible for damping the spring overall movement and oscillation.

How do coilovers work

Now that you know what is the function of the spring and shock absorber.

Here’s how they actually work to accomplish their important job.

The shock absorber

Coilover components names
Shock absorber main piston

Shock absorbers operate on the foundation of a concept known as hydraulic resistance. (1)

They are composed of a hydraulic fluid camber, a main piston, a floating piston, and a pressurized gas section. (see image #1)

When you hit a bump in the road, the shock absorber cylinder moves up and down, while the piston remains static. As the shock absorber cylinder goes up and down, the hydraulic fluid is forced to pass through small holes in the main piston head creating resistance. (see image #2)

This resistance is how the damping and absorption of bumps are achieved. It is also this resistance that controls the oscillation of the spring.

However, all the rapid up and down movement inside the hydraulic fluid will cause it to foam up. If that fluid foams up, the shock absorber is rendered ineffective. (2)

This is why, at the bottom of some shock absorbers, there is a high-pressure gas section. (see image#1) The pressure from the gas chamber exerts pressure on a floating piston (without holes), which in turn exerts pressure on the hydraulic fluid, preventing foam buildup.

The coil spring

A coil spring is essentially a steel rod bent into coils. When a coil spring compresses, it stores energy and hence always wants to return to its original height.

Different coilover features and options

As we said previously coilovers are arguably the most customizable and adjustable suspension component.

This is where they mainly get their popularity from, since car enthusiasts from high-performance junkies to floor-scraping stance car lovers can utilize coilovers to achieve their goals.

The following list showcases all the different features, adjustments, and options of coilovers.

Dual spring rate Spring
Coilovers Descrptions
Rebound and compression damping of coilovers

1. Spring Rate 

The spring rate indicates how stiff your spring is. For example, a spring rate of 100 lbs per inch means that putting 100 pounds on that spring will compress it by 1 inch.

If you were to put an extra 100 pounds the spring would compress an extra inch and so on until the spring bottoms out. However, this only works with a linear spring rate.

There are many different types of spring rates such as the ones showcased below.

  • Linear rate: The spring rate stays the same throughout the total coil spring length.
  • Dual rate: There are two spring rates on the same spring. Usually a softer spring rate for the bottom half and a stiffer rate for the top half. The softer rate helps to absorb shocks and bumps while the stiffer rate will offer good handling. (see image #3)
  • Progressive rate: The rate becomes progressively stiffer as you go up the spring.

Extra (second) spring

Some coilovers will have a completely separate second spring on them. The spring is substantially smaller and has no effect on driving or handling. The extra spring is there simply to hold the main coil spring in place when the suspension is unloaded.

2. Threaded coilover body 

Almost every performance coilovers is fitted with a threaded body. A threaded body means what it says, the body of the coilover (mainly the exterior shell of the shock absorber cylinder) is threaded. (see image #4)

These threads allow for two different adjustments.

  • Spring perch: Spring perch is how you keep your coil spring snug and in place. Additionally, it is how you change ride height for coilovers without a ride height adjuster. However, changing ride height with spring perch comes with its downsides such as, the spring not being snug when unloaded or the main piston in the hydraulic chamber not sitting in its intended spot. (see image #4)
  • Ride Height: A ride height adjuster is simply the bottom coilover mount capable of moving up and down along the threads. This is the ideal way of adjusting ride height since it allows you to do so freely while keeping an ideal spring perch. (see image #4)

From there if you are buying coilovers mainly to lower your car you should look for a set with a ride height adjuster mount.

3. Adjustable Damping

The damping of your shock absorber can also be adjusted.

There are two types of damping such as compression and rebound. (see image #5)

  • Compression damping: This damping occurs when the spring compresses
  • Rebound Damping: This damping occurs when the spring decompresses (returns to its original height)

These two types of damping are very often very easily adjusted. There will often be 1 or more small spinnable buttons at the top of the coilover.

These buttons make little “click” sounds as you spin them and this is why the damping adjustment is often referred to as clicks. (For example: 20 clicks of adjustment)

When you spin the knobs every click tightens the main piston tolerance making it harder for hydraulic fluid to go through and therefore creating more resistance.

Coilover adjustment settings are divided into four groups.

  • 1-way adjustable: You can only adjust the compression and rebound resistance together.
  • 2-way adjustable: You can adjust compression and rebound resistance separately.
  • 3-way adjustable: You can adjust rebound high and low speed and compression separately.
  • 4-way adjustable: You can adjust high and low rebound and compression resistance all separately. 

Usually a 1-way adjustable coilover is more than enough for the average car enthusiast. If you are willing to spend more money you could go with a 2-way adjustable and play around with the settings but it is often not necessary.

However, the 3 and 4-way adjustable is most likely overkill unless you need precision adjustment for performance.

4. Upper mounts

The upper mount or top hat can either have a rubber bushing or a steel bushing usually called a pillow ball mount.

  • Rubber: Great at absorbing road noise and vibration
  • Steel: Great responsiveness

You can also add to your top hat a camber plate which serves the purpose to adjust the camber of your wheels.

5. External reservoir

The reservoir is generally a relocation of the high-pressure gas chamber. Having this chamber on an outside reservoir can help prevent foam even more.

External reservoirs are used mainly for off road purposes where uneven terrain and bumps are common. For a normal street or track car the use of an external reservoir is not bad in any way but is also not really necessary. 

coilovers pros and cons

Pros

  • adjustability 
  • customization and options
  • Improved handling
  • car height and stance customizations
  • Availability and versatility 

cons

  • Price
  • Too many option (can cause confusion when buying)
  • Stiffness (cause vibration and rough ride)

Coilovers FAQ

Coilovers vs lowering spring 

Coilovers and lowering springs are not exactly the same thing. Lowering springs are frequently regarded as the budget alternative to coilovers.

This is because the spring is responsible for changing the stiffness and height of the car. As a result, by purchasing only the coil spring, which is far less expensive, you can still obtain the handling and stance benefits.

However, there is no adjustability after purchase, and the handling gains may be modest depending on the other suspension parts fitted in your vehicle.

How much should be spent on coilovers

Generally speaking the more features a set of coilovers has the more expensive it will be. For the average person who just wants to lower their car, have a stiffer suspension, a good handling performance, and durability a high ticket set of coilovers is not necessary.

A mid-range price (About $1000 to $1400) will give you a coilover with all the options truly you need. Higher price ranges are recommended for more intense racing needs.

Lastly, cheapening out on coilovers is a very bad idea. Buying poor quality or even knockoff suspension can lead to serious injuries if a malfunction occurs.

can you rebuild coilovers

The short answer is yes, at least usually. There might be certain exceptions where your coilovers aren’t rebuildable.

However, once your dampers are blown, and springs start to sag, the majority of the time people will just buy a new set. Therefore, depending on the price of rebuilding and the price of a new set for your car you can decide which way you will go.

conclusion

In conclusion, coilovers are a popular suspension modification among car enthusiasts due to their high adjustability and performance enhancement capabilities.

Coilovers, which consist of a coil spring and a shock absorber, function similarly to any other spring and shock absorber system. The coil determines the height, and stiffness of the suspension. The shock absorber dampens spring oscillation and absorbs road bumps.

Coilovers however offer various features and options, including spring rate adjustment, threaded coilover bodies for ride height adjustments, adjustable damping settings, upper mounts with rubber or steel bushings, and the option for an external reservoir.

Nevertheless, there are some disadvantages to consider, such as a high price depending on the options chosen, the possibility of confusion due to too many possibilities on the market, and the firmer ride, which results in higher vibration and roughness.

Ultimately, the decision to invest in coilovers should be based on personal requirements, preferences, and intended usage. It’s important to choose a reputable brand and consider factors like budget, desired performance, and the specific requirements of your vehicle.

Disclaimer: The following content is provided solely for recreational and informational purposes only. It is essential to note that any modifications or alterations made to a car’s suspension system can pose significant risks and hazards. Engaging in such activities without the necessary expertise, knowledge, and understanding of automotive engineering may result in severe accidents, injuries, or even loss of life.