The two most common suspension system types are:
Dual Wishbone — includes a ball joint mounted to each the upper and the lower suspension control arms.
MacPherson Strut — includes a single ball joint located on the lower control arm.
In the aftermarket, suspension systems continue to experience wear and fatigue throughout the life of the vehicle. Factors that can contribute to wear and fatigue are road conditions, weather, and vehicle load and weight changes.
There are 3 basic types of ball joints that are used in suspension systems:
- Press in - a press in ball joint design works on the principle of friction, or interference. The ball joint is larger than the hole inside the control arm or knuckle. When the ball joint is pressed into the control arm, a high amount of friction is generated that holds the ball joint tightly in place.
- Bolt In - a bolt in ball joint uses a mounting flange that bolts on to the control arm using 3 or more bolts and nuts. Many of the OEM ball joints on this application will come riveted only on the original vehicle. As they wear and need to be replaced, the rivets are removed, and the ball joint is replaced with an aftermarket bolt in design.
- Unitized - a unitized ball joint application replaces the individual ball joint. This design completely integrates the ball joint pivot into the design and construction of the control arm assembly, forming one solid container arm. This design has become very popular with the use of aluminum design control arms. Replacement of unitized ball joints requires the entire control arm assembly to be replaced.
To compensate for wear on control arm receptacles, Mevotech X Factor ball joints are manufactured with the following features:
- High friction knurling around the outside of the ball joint housing to provide the control arm maximum grip to keep the ball joint firmly in place.
- Blue polyurethane boots to prevent moisture and foreign particles from entering the internal contract area
- Black oxide coating to prevent rust and corrosion from affecting the ball joint
- Metal to metal internal designs to allow ball joints to be swiveled and greased at regular intervals, increasing overall life span and durability.
Ball joints act as the pivot point for suspension articulation. Ball joints are designed to allow the suspension to move independently without interfering with the action of the wheel. This independent motion isolates the movement of the car or truck wheel from the chassis of the vehicle, creating a smooth and quiet ride.
Depending on the location of the ball joint, it will be either a load-bearing or a non load-bearing joint. Load-bearing ball joints are subject to continual load stress, and because of this, they must be inspected frequently to ensure optimal performance. Excessively worn ball joints require replacement.