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What are Coilovers? What do they do?

What are coilovers? In a nutshell, coilovers are adjustable suspension. Coilovers let you adjust the height of your car and the hardness of your suspension

Coilovers vs lowering springs

What are coilovers – The different types

Coilover suspension are available in different types.

1.Height adjustable, fixed damping

We do not recommend these types of coilovers as it defeats half the reasons to fit coilovers in the first place ie it does not give the ability to adjust softness/hardness

2.Height adjustable, adjustable damping

This type of coilover is available in two different forms.

a.Height adjustable using spring pre-load (H&R, Eibach. Generally European manufacturers)

b.Height adjustable with independent bottom bracket (Japan, Taiwanese manufacturers eg TEIN, K-Sport, BC)


Coilovers are a complete suspension kit, you remove the original springs and dampers from the car and you install the coilover kit. In many ways it is easier to install a coilover suspension kit than the stock suspension.

Some kits need you to use your car’s original top mounts, other kits are supplied with the top mounts.

Which top mounts do we recommend?

There are pluses and minuses to using both. For maximum adjustability, top mounts from the coilover manufacturer are the way to go. However, depending on the type of suspension your car has eg Double wishbone, an adjustable top mount may serve no purpose as it is impossible to adjust the geometry of your suspension with the top mount.

Questions to ask the shop about the coilover kit before you buy (top mounts)

  • what type of top mounts they supply for your car on the front and the rear.
  • if they supply top mounts, ask them if they adjustable on the front, if not why not
  • are they adjustable on the rear, if not why not
  • and if the top mounts are adjustable
  • what do they change on the front? eg camber and/or caster.
  • what do they change on the rear? eg camber and/or caster.

The cars original top mounts will probably give a very slightly better/comfortable ride over any coilover manufacturer top mount. You have to weigh up if comfort is more important than adjustability for you.

Height adjustment

As mentions above, there are two types of height adjustment used on coilover suspension

The first is adjusting the spring seat. Compress the spring (add preload to the spring) and the suspension is higher, uncompress the spring (no preload on the spring) and the suspension is lower.

Two main problems with this method of height adjustment

1-When you lower the car you also reduce the travel of the suspension, how much it can move, which will make the car more likely to bottom out and hit the bump stops. This can make the car uncomfortable and noisy.

2-You change the characteristics of the suspension when you add spring preload. You reduce the amount of droop in the suspension and you make the ride slightly harder. Great for performance not so good if you live in an area with bumpy roads

The second type of adjustment is with an independent bottom mount.

When you change the height of the suspension the travel in the suspension does not change

You are not changing the spring characteristics of the car when you can change the ride height

In short coilover suspension with an independent bottom bracket eliminates the two main problems with adjusting ride height with spring preload but it does have three main downsides

Price – Because the suspension has more parts, they tend to be more expensive

Weight – Because the suspension unit has more parts, it tends to be heavier

Adjustability – Because a bottom bracket gives you so much freedom with height adjustment, it can be difficult finding the optimum ride height

Which do we recommend?

Height adjustment with an independent bottom bracket if you want maximum adjustment.

Via spring seat if you think you will be setting-and-forgetting your ride height, ie not constantly adjusting the height for different tracks/conditions.

What are coilovers – Damping adjustment (Hardness/softness)

Most coilover dampers are adjustable by turning a knob mounted on top of the damper, if it is not possible to use this technique, for example interior trim in the car does not allow it, the damper adjustment could be at the bottom of the damper

Electronic damping adjustment from inside the car is also available from some coilover suspension manufacturers eg TEIN and CUSCO.

There kits are much harder to install than non electronic kits because of the extra wiring.

Is electronic adjustment worth it?

In my opinion no, I hardly ever alter the dampers when I have found a setting I like, and if I do want to change the damping, the process only take a couple of minutes to do manually. For me the extra expense, the extra install work and addking extra parts which may break at some point is not worth the benefits.

What are coilovers – Summary

Coilovers let you change the height and hardness of your suspension

We recommend suspension with adjustable bottom brackets for height adjustment, suspension with adjustable damping. On top mounts, I am in the middle, although OE top mounts are much cheaper to replace and offer a slightly nicer, more expensive feeling ride and top mounts from the coilover manufacturer.

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This page was last modified Aug 26, 2021 @ 8:47 pm

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