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.

Power Steering Pumps

A pump which supplies hydraulic pressure to reduce steering effort. The pump is usually a belt drive vane style pump. A fluid reservoir may or may not be present, the pump itself using either specialized power steering fluid or automatic transmission fluid.

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.

Steering Racks

The device by which the movement of the steering wheel is transferred to the front wheels of an automobile. They are the metal component in a rack and pinion steering unit upon which gears silde back and forth, determining how far a corresponding wheel turns.

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

Track Rod Ends

One of the transverse bars connecting the steering system to the steering arms; the link between the pitman arm and the steering-knuckle arm.

Universal Joints

A flexible double-pivoted joint that allows driving power to be carried through two shafts that are at an angle to each other. It consists of two Y-shaped yokes and a cross-shaped member called the spider. The four arms of the spider are assembled into bearings in the ends of the two yokes. With the normal cross-and-two-yoke universal joint there is some change in speed when the driveshaft and the driven shaft are at an angle to each other. The change in speed occurs because the driven yoke and driven shaft speed up and then slow down twice with every revolution of the drive line. The greater the angle between the drive and driven shafts, the greater the speed variation. To eliminate this speed variation, which results in increased wear of the affected parts, constant velocity joints are used on many cars. In front drive vehicles, it is called the Constant Velocity joint.

Wheel Bearings

The inner and outer bearings found at each wheel cushion the contact between the wheel and the spindle it sits on. They’re packed with grease to prevent wear from the friction produced by the turning wheels.

Wheel Cylinders

A wheel cylinder is a component in a drum brake system. It is a device usually located above the shoes at the top of the wheel. Actuated by hydraulic pressure, it pushes the brake shoe outward against the drum.