Coilover Upper Mount Types
Coilover Upper Mount Types & What They Look Like
This is a brief article explaining the different types of coilover upper mounts and what they look like. The purpose of this article is to inform new coilover customers of the different types of upper mounts that coilover kits come with and what they look like. Coilover Upper Mounts, also called Top Mounts, are responsible for affixing the coilover piston shaft to the upper shock/strut tower of the vehicle (they connect the suspension to the body of the vehicle). Some vehicles have captive upper mounts built into the chassis and in such cases the coilover will reuse the Original Equipment Manufacturer – “factory” (OEM) upper mount.
We will dive into more detail about each upper mount, what they do, how they function, and how they relate to various types of OEM suspension designs in another article.
Adjustable Camber Plate Upper Mounts
Adjustable Camber Plates, or “Camber Plates,” are the first upper mount type we’ll cover. Adjustable Camber Plates are most commonly located on the front the coilovers for vehicles with a McPherson Strut design and are considered standard equipment on most aftermarket coilover kits nowadays. Only vehicles with an OEM McPherson Strut Suspension design can benefit from camber plates which is one of the reasons they’re not found on all coilover kits. Adjustable camber plates can also be used on the rear coilovers for vehicles with rear McPherson Strut Suspension such as the 1997-2001 Subaru WRX GC8 and 2002-2007 Subaru WRX GDB.
Adjustable Camber Plates are distinguishable by their overall adjustable design as they have slots that run perpendicular to the centerline of the car to allow the camber bearing housing to move closer or further away from the centerline, thus inducing negative or positive camber at the wheel, respectively. Another notable feature of coilovers with camber plates is an upper spring seat which sits below the camber plate that allows for the shock shaft to pivot inside the camber plate. This means the spring does not sit on the bottom side of the upper mount as commonly seen on rubber upper mounts.
Rubber Upper Mounts
Rubber Upper Mounts, unlike Camber Plates, are non-adjustable and are arguably the most common upper mount type found on aftermarket coilovers. Rubber upper mounts aren’t actually rubber, they’re generally made of aluminum and sometimes steel, and contain a rubber bushing in the middle where the coilover piston shaft passes through. Many times, people think rubber mounts will look similar to their OEM mounts when that generally isn’t the case. There are some cases out there where a coilover manufacturer will use an OEM-type upper mount on their kit, but they’re few and far between nowadays.
Rubber upper mounts are distinguishable by their solid aluminum mating surface with rubber inner bushings protruding slightly on the top and bottom side of the mount. Many coilover kits that utilize a rubber upper mount will not have a spring seat that sits below the mount. Instead, the upper part of the spring will sit against the bottom side of the rubber upper mount.
Pillowball Upper Mounts
Pillowball Upper Mounts are not that dissimilar in their appearance to rubber upper mounts at first glance, especially when installed on coilovers. What makes them different is pillowball ball upper mounts have a spherical bearing in the center where the rubber bushing would be on the rubber upper mount. Pillowball upper mounts, as their name implies, contain a spherical bearing (a ball-shaped bearing) that allows for angular movement, and is located at the center of the mount where the piston shaft passes through. The spherical bearing used in pillowball upper mounts is very similar to the type used in adjustable camber plate upper mounts in order to allow for angular rotation.
Pillowball upper mounts are distinguishable by their absence of rubber bushings in the center of the mount and lack of adjustability. They will have a clearly visible spherical bearing at their center and will generally have a lower spring seat where the top of the spring sits. Not all coilover company’s employ the use of an upper spring seat with the use of pillowball upper mounts, but in order to get the maximum benefit out of them, an upper spring seat must be used.
Reuse OEM Upper Mounts
The final coilover upper mount type we’ll talk about isn’t a mount at all, it’s actually the absence of a mount all together, also known as Reusing OEM Mounts. Unfortunately, not all vehicles can accept the use of an aftermarket coilover upper mount, and in those cases, coilover manufacturers engineer their coilover piston shafts to reuse the OEM upper mounts for the vehicle rather than not make a kit at all. There are also some manufacturers that do not provide upper mounts on all or some of their coilover models, such as KW Coilovers and the Tein Street Basis Z Coilover Series.
The lack of an upper mount on the coilover is the only way to describe what it looks like. If there’s no mount, on the front or rear coilovers, then they will reuse the OEM upper mounts from the vehicle. Some OEM upper mounts require a conversion plate to accommodate the coilover springs and in those cases the OEM mount will mate with the aftermarket coilover adapter parts.
Adjustable Camber-Caster Upper Mounts
As a bonus I’ll briefly touch on one other coilover upper mount type and those are Adjustable Camber-Caster Upper Mounts (also known as camber-caster plates). As the name implies adjustable camber-caster plates provide the ability to adjust camber and caster at the wheel by moving the top of the shock in both the longitudinal and lateral directions. As previously mentioned with adjustable camber plates, when you move the top of the shock laterally, you move it closer or further from the centerline of the car, which induces either positive or negative camber. With the addition of caster adjustment to the upper mounts, it allows the top of the shock to move longitudinally, which induces either positive or negative caster. We’ll go into what camber, caster, and steering axis inclination (SAI) all mean and how they relate to each other and the handling of a vehicle in another article but I wanted to quickly touch on caster plate upper mounts since they are available for certain coilover applications.
They’re distinguishable by their overall unique appearance and can have slots running perpendicular and/or parallel to the centerline of the car as well as multiple “bolt patterns” for adjusting the plates in different directions, or a combination of both.