Ball Joints

A flexible joint using a ball and socket type of construction, used in steering linkage setups, steering knuckle pivot supports, etc. Their flexibility helps to compensate for the changes in the wheel and steering when turning or hitting a bump on the road. There are usually upper and lower ball joints attached to the upper and lower A-arms. Some have a grease nipple to allow periodic lubrication.


A protective liner or sleeve that cushions noise, friction, or movement. Suspension bushings are often made from two concentric pipes with a sleeve of rubber in the dividing space.

Coil Springs

A section of spring steel rod wound in a spiral pattern or shape. Widely used in both front and rear suspension systems. Like large metal bed springs, these coils cushion and absorb the shocks and bumps as the vehicle is driven. They are usually found near the front wheels, but some cars have them in the rear as well. Often the shock absorbers run up the center of the coil springs.

Gas Springs

A gas spring is a type of spring that, unlike a typical metal spring, uses a compressed gas, contained in a cylinder and variably compressed by a piston, to exert a force. Gas springs are used frequently in automobile construction, where they are commonly used to support the weight of vehicle doors while they are open. They are also used in furniture, medical, and aerospace applications.

Idler Arms

In a parallel relay-type Steering linkage, it is one of the connecting levers. The steering Gearbox is attached to a Pitman arm which converts rotary motion to lateral motion. The pitman arm connects to a transverse centerlink which connects to the idler arm attached to the Frame side rail on the opposite side of the vehicle. The ends of the centerlink connect to two adjustable Tie rods that transmit the lateral movement of the centerlink to the steering arms at each steering knuckle.

Leaf Springs

A length of flat spring steel plates bent in an arch usually with curled ends (eyes) to allow mounting to the frame. The eyes are usually filled with rubber bushings to reduce noise when the leafs flex. A bolt through the front eye secures the spring to the frame, and a pin through the rear eye attaches the spring to a shackle. Another pin attaches the shackle to the frame. The pivoting shackle accommodates the changes in the effective length of the spring as it flexes. The axle housing is secured to the leaf spring with two U-bolts on either side. Some applications need only one leaf spring; but most have several leaves, each smaller than the other, nested together to help the main spring. Rebound clips are used at the ends to hold several leafs together to keep them from separating sideways. In a single-leaf application, sometimes two holes are drilled in the center of the main spring to mount a u-bolt which surrounds the axle. Also called semi-elliptic springs.

Pitman Arms

A short lever arm splined to the steering gear cross shaft, the pitman arm transmits the steering force from the cross shaft to the steering linkage system. In this way rotary motion of the steering wheel is turned to lateral movement of the arm. Also called a drop arm.

Shock Absorbers

Properly called a damper, this is an oil filled device used to control spring oscillation in the suspension system. At least one shock absorber is found at each wheel.

Sports Springs

Component Distributors stock the Kilen range of Sports Springs. Our Kilen Springs are called “sport” rather than “lowering” springs because these kits are designed to enhance the driving conditions for the customer via stiffer springs with moderate lowering effect. Lowering springs usually are not stiffer and only lower the car.

Strut Mounts

A strut mount is a component that attaches to the strut, and is located above each wheel in an area called the suspension tower. The strut itself is an assembly of shock absorber and spring and is becoming more commonplace on vehicles with 4 wheel independent suspension. Rear strut mounts are usually a solid component, incapable of independent movement as they are the upper mounting point for the suspension. Front strut mounts can pivot, allowing the wheels to turn left and right.

Suspension Arms

A suspension arm provides support between the wheel knuckle and the vehicle frame. The end attaching to the vehicle allows the arm to pivot while maintaining support – the opposing end is tooled to connect to a wheel knuckle. Component Distributors stock a full range of HRA suspension arms, with the full Howard Roberts’ range comprising of over 4,000 references.

Suspension Links

Any arm which links the chassis to the axle