A Guide to Understanding Coilovers

The factory suspension system in your car improves its control and handling, giving you a smooth ride. It achieves that by helping to manage the friction between the car's tires and the road. The suspension system also provides comfort on uneven terrain.

You can improve your car’s suspension system using aftermarket upgrades such as coilover kits, lowering spring kits, adjustable shocks, and struts . However, if you really want to improve your car’s handling, especially high-speed handling, you should consider coilovers.

What is a Coilover?

The name coilover is a short version of ‘coil spring over shock’. Typically, what you get is a coil spring that covers a shock or a strut.

So, how is it different? Most of the other suspension systems have the spring separate from the shock. In fact, most car owners buy the two components separately. However, a coilover comes with preassembled shocks and springs that are designed to perfectly fit each other and work in harmony. This will not only make your car look better by reducing the wheel gap, but also greatly improve the car's handling and performance.

How Does a Coilover Work?

The typical suspension system features a controlling arm, coil spring and a shock absorber or a strut. The difference between a strut and a normal shock is that a strut carries some of the weight of the car. Most of the time, the spring is mounted on the strut. In case of any compression on the strut, or the spring, or both, the wheel moves upwards towards the body of the car.

The mechanism of the coilover is similar. It has a longer coil spring that is coiled around the strut. For the upward movement of the wheel, both the shock and the spring must compress. The spring carries the weight upon compression while the strut transfers or damps the bouncing to the spring.

Coilovers vs. Springs

The dilemma most car owners face is between lowering springs and coilovers. Which is better? The answer to that question depends on your needs. Do you want to lower the ride height? Or, do you want a height adjustable car? Again, do you want your shocks to have rebound and compression adjustment?

The fact is that lowering springs simply lower your car. They do not provide any other adjustment to your shocks. You cannot adjust its height once you install them. The amount of drop they provide is preset. So, if you needed to lower or raise your car, you would have to install another set of lowering springs. 

Lowering springs can be used with factory stock shocks or with custom performance shocks. However, the springs you buy might not be a good match for your shocks. Like most drivers, you buy shocks from one brand and springs from another. Most likely you ran into the problem where the spring is too stiff on the shock. The result is a car that is low, but the handling is worse than before the spring installation. This will also shorten the lifespan of your shocks.

Coilovers solve most of the problems lowering springs present. For starters, the coil spring and the strut are made to perfectly fit each other. That alone improves handling significantly. Moreover, understanding coilovers allows for height adjustments and improves the rebound on the shock.

Types of Coilovers

Coilover Sleeves 

Coilover sleeves resemble lowering spring. The main difference is that they are height adjustable. You can choose from a wide range of rates and lengths. They do not have a shock or strut. They are installed on your existing shocks, and they come with top mounts. These are entry level suspension upgrades – they have a low price and do not come with a Camber Kit. 

Non-shock Adjustable Coilovers 

The key feature of the non-shock adjustable coilover is height adjustability. This is a full-bodied coilover that comes with shocks. However, the shock is non-adjustable. That is to say; you cannot adjust the rebound, compression, and stiffness of the shock.

Different manufacturers have different designs. Most provide them pre-assembled with top mounts. These coilovers are a good option if you want to lower your car and have the choice in the amount of lowering you want. With this type of coilover, you have to purchase a Camber Kit separately.

Shock Adjustable Coilovers 

These coilovers sport the same features of the non-shock adjustable coilovers. The difference between the two is the shocks. In the shock adjustable coilover, the shock is adjustable and perfectly dials into the suspensions. The shocks allow smooth rebound and compression, and you can adjust the stiffness.

Shock adjustable coilovers are the most popular type of coilovers. They provide a smooth ride in your daily driving. Racers like them as they can adjust the stiffness – a feature that is crucial for track use. The price is mid-range, and they usually do not come with a Camber Kit.

Shock Adjustable Coilover with Camber Kit 

A shock adjustable coilover with a camber kit is one of the best suspensions upgrade you can get for your car. These coilovers come with height adjustment and adjustable shocks. Normally, they feature a front camber kit, with some advanced versions sporting the rear camber kit.

Advantages of Coilovers

The two main advantages of coilovers are improved handling and adjustability. Changing a car’s handling performance usually involves removing most part of the suspension system. But, a well-designed coilover allows you to improve the handling without changing much of the other parts of your car’s suspension setup. And, you can install a coilover in almost any car.

Very few suspension upgrade kits provide height adjustability. As much as you want a low ride setting for your car, it will not be convenient in all terrain. So, being able to raise the ride height anytime you want is a huge advantage.

Coilover Installation

It is recommended that you get your coilovers installed at an auto shop. Still, a D-I-Y installation is not out of the question. Depending on the manufacturer and model, coilovers are shipped in different ways. You can either get them fully extended, collapsed, with the springs mounted, or with separate springs.

The first thing you should do when you buy them is to inspect the contents of the package. You should determine that they are the right size for your car. Also, check that you have received sets for the rear wheels and the front wheels.

Step 1: Install the Spring 

Installing the springs should be the first step if the coilover came with the springs separate. Most coliovers have an instruction manual detailing how to install the springs.

Typically, you will have to first extend the shock. Then, slide the spring over the shock until it comes in contact with the spring retainer, also called the preload nut. If the coilover is dual rate, install the slider first before mounting the lower spring from the lower end of the shock.

After installing the lower spring and the upper spring, there should be zero preload. So, you should make sure that both springs snug together. Also, at zero preload, there are no more than 3 inches of threads above the coil adjustment nut. Zero preload guarantees that there is no play between the coil nut adjusters, the springs, the slider, and the spring plate.

Step 2: Install the Coilover 

To install the fully assembled coilover, suspend the chassis using a jack and make sure the suspension is in full droop. Then, bolt the coilover using the right bolts (usually grade 8) with the lock washers and nuts. Lastly, lower the vehicle slowly.

If you did everything correctly, after the vehicle weight rests on the coilovers, it will settle at your desired ride height. If it is slightly below the ride height, you simply need to add the amount of preload. You add preload by rotating the upper coil adjustment nut down.

However, if it settled way below or way above the desired ride height, you need to change the springs because the problem could be that the spring rate.

Step 3: Test Run 

Now that you have installed the coilovers and set the correct preload, you can go for a test run. The test run will let you know if the coilovers need shock tuning or shock valving. Your main concerns on the test run should be the feel of the suspension. You want the coilover to achieve light handling, and also need the suspension to be strong enough to adequately support the weight of the vehicle.

Considerations When Purchasing Coilovers

In the case of coilovers, you get what you pay. That is to say that the more expensive coilovers will achieve the best handling performance for your vehicle. A cheap coilover may provide the same functionality as an expensive coilover. However, the cheap coilover will not provide the same durability, safety, and performance as a well-designed quality coilover.

Note that coilovers may be quite pricey. The point is, if your vehicle currently has good handling, the cost of installing coilovers may not be worth it. However, it makes sense if you are considering changing your suspension system.

Additionally, the advantages of coilovers are great for racing. They provide good distribution and balance of weight at all the four corners. That is important since during racing you want to get maximum traction.

Conclusion

Coilovers are some of the best suspension setups invented in the automobile industry. Coilover suspension improves performance and handling in both daily driving and race driving. Plus, they are prestigious. They are regarded as useful aftermarket parts in the car community. A good number of racing cars and luxury cars run on coilover suspension systems.