In the steering and suspension system of an automobile, the ball joints enable the steering knuckle to swivel and turn smoothly. They’re constructed of a ball stud fixed into a socket housing. The socket housing is attached to the control arm. They allow the steering knuckle to swivel smoothly between the control arms or strut towers while turning and going over bumps. Binding ball joints cause memory steer.
Ball joints wear from time or lack of lubrication. If the dust boot is broken, lubrication is leaking out and the ball joint will begin to bind. Lack of lubrication is a common cause of failure. They begin to rust as lubricant seeps out and water begins to seep in. The dry ball joint causes a popping noise when the driver turns the wheel or comes to a stop.
When the castle nut is tightened on a tapered fitting like a ball joint, never back it off to install the cotter pin. This will result in a loose fit and movement between parts. Many replacement ball joints have a zerk grease fitting and must be lubricated after installation. Others are sealed and contain sufficient lubricant from the parts manufacturer.