Ball joints are a commonly replaced suspension component because they wear out. The life of a ball joint depends on its location (upper or lower), whether it is loaded or a “follower” joint (loaded joints usually wear out sooner), mileage and environmental exposure. Most ball joints on newer vehicles are sealed and do not require periodic greasing. They are a “low-friction” design with a polished ball stud and a polymer or powder metal bearing. Lubrication is impregnated into the bearing, eliminating the need for a great fitting.
Greaseable ball joints, by comparison, usually have a “gusher” style steel bushing that requires regular doses of grease to maintain lubrication inside the joint. Greasing the joint also helps push contaminants out of the joint. Most motorists have no idea what shape their ball joints are in because the joints are out of sight and out of mind.
They are seldom inspected unless an unusual tire wear problem is noticed or the vehicle is receiving a pre-alignment suspension inspection. The amount of wear that is allowed in a ball joint depends upon the application, and can vary up to .050 inches or more. Some ball joints have built-in wear indicators, but most are checked by prying against the suspension while watching for excessive movement in the joint.
A loose or worn ball joint can be dangerous and should be replaced as soon as possible. Why? Because if a ball joint pulls apart or breaks, it will cause the suspension to collapse. That, in turn, could cause a loss of steering control similar to a tie rod end failing. The right front ball joints on many vehicles typically wear out sooner than the ones on the left side of the vehicle. The reason for this is that right turns are typically sharper than left turns, so there is more rotational wear in the right ball joints than the left.
Ball joints also can wear out prematurely if they are exposed to a lot of road splash — especially road salt in colder northern climates. The jolts and bumps that occur with normal driving also take a toll on the ball joints over time. Potholes and rough rural gravel roads can pound the ball joints unmercifully. The most common symptom of worn ball joints is suspension noise or clunking when driving over bumps or dips in the road. Worn joints can also cause unwanted negative camber changes in wheel alignment that increase inner shoulder wear on the tires. If a customer needs a new ball joint, recommend replacing all of the joints at the same time. If one joint has failed, chances are the other joints may be nearing the end of their service life, too. Yes, it costs more to replace all of the joints but doing so restores the suspension to like-new condition and eliminates the risk of another joint failing at some point down the road.