In the following pictures we'll highlight each of the major parts of the coilover starting at the top and working our way down. Please know that now all coilovers are Double Wishbone-style, there are also McPherson, and separate spring & shock coilovers, which we'll cover in another post. It's important to note that each of the following parts and/or images will vary based on coilover manufacturer and their design, but they all share the same major parts, regardless of how they're designed to look.
Damping Adjustment knobs, also known as "Adjustment Knobs" or "Damping Knobs" are used to fine tune a damper that has adjustable damping capabilities. This is just one example of an adjustment knob located at the top of a coilover but there are many different styles. One thing to note is that not all coilovers have adjustable damping, some have fixed damping set by the manufacturer and cannot be adjusted by the end-user. Another important note is about the location of the damping knob, they are most commonly found on the top of the coilovers, but they can also be found further down on the shock shaft under the upper strut tower. Damping knobs located further down on the shock shaft are most commonly referred to as "dial" or "wheel" adjusters due to their shape.
The piston shaft top nut, also known as the "top nut," is located directly below the damping knob and holds the upper mount assembly to the shock piston shaft.
The upper mount is located directly below the top nut and is responsible for mating the coilover to the upper strut tower of the car. The upper mount picture above is a Pillowball Upper Mount and you can read more about those in our Coilover Upper Mount post.
The upper mount picture above is an Adjustable Camber Upper Mount and you can read more about those in our Coilover Upper Mount post.
The spring is located between the upper mount and lower spring seat. The spring sits over the damper piston shaft as well as the dust boot and bump stop and is responsible for controlling the weight of the vehicle. Coilover springs come in 3 distinct profiles, Linear (same inner diameter [I.D.] top & bottom), Variable Diameter Linear (different IDs top & bottom), and Barrel-Shaped Linear (same ID top & bottom with a larger ID in the middle of the spring - hence the name "barrel").Lower Spring Seat:
The lower spring seat sits directly below the spring as the name implies. On coilovers with independent height adjustment from spring tension/shock stroke, the lower spring seat is responsible for holding preload on the spring.Damper:
The damper, or “shock,” consists of the damper body which houses the oil, nitrogen, piston, piston shim stack, and piston shaft (there are more parts but for the bases of this article we’re going to keep it simple). On the piston shaft you’ll find the dust boot and bump stop pictured off to the side of the piston shaft in the image above.Lower Mount Lock Ring:
Lower mount lock rings are pretty standard in their appearance across coilover brands with some variations in design like BC Racing's "concave lock ring & lower mount." Some coilover manufacturers supply a compression washer that sits between the lower mount and lower mount lock ring to help prevent them from coming loose. They're generally very thin and have a wavy shape to them.Lower Mount:
Lower mounts come in many different shapes and size but there are 4 main types, eyelet lower mounts (as pictured above), fork lower mounts, slip-in lower mounts, and clevis lower mounts such as those found on McPherson Strut coilovers.