The top ball joint acts as a pivot between the wheels and the suspension and connects the upper control arm and the knuckle together with an upper control arm seal boot in the middle. Although there are front ball joints in vehicles, some high-performance vehicles also have rear ball joints.
The top ball joint consists of a ball stud and bearing which sits inside a housing socket. Underneath the bottom side of the bearing is a rubber pressure ring. Lastly there is a grease fitting which acts as a guide for wear.
To inspect for damage of the top ball joint you need to ensure that the vehicle is supported by the wheels. Ensure that the grease fitting is free of dirt and debris and then move a screwdriver or your fingernail across the cover. If the grease fitting is either flush or recessed into the cover the top ball joint needs replacing.
Signs of failure include clicking, popping or snapping sounds when the wheel is turned. Failures of a ball joint are very serious and can cause the wheel’s angle to be incorrect.