When do the ball joints need to be replaced?
Your car has many components that are vital for safe driving, and a ball joint is one of them. A ball joint is a part of the front suspension. It connects the control arm to the part that holds the front wheel called a steering knuckle, see the illustration. Bad ball jointBall joint in a typical front-wheel drive carThe connection is flexible, so the front wheel can steer and move up and down. Modern cars have at least two ball joints in the front end; many trucks have four.
In many cars, a ball joint is built into the control arm and is replaced as one unit. We covered control arms in this separate article: When do control arms need to be replaced? Here we will focus on the type of ball joint that comes as an individual part, like in these photos. What does it do and when should it be replaced?
A ball joint consists of a housing (socket) and a stud with a ball; it serves as a flexible joint. In some trucks, ball joints have grease fittings and need to be greased periodically. The majority of modern cars have non-serviceable ball joints that are greased at the factory and sealed with a rubber or polyurethane dust boot. Ball jointBolt-in ball joint.Ball jointPress-in ball joint.
When do ball joints need to be replaced?
There is no mileage requirements. Ball joints need to be periodically inspected and replaced if worn. We have seen them last for over 160K miles, but potholes, speed bumps and road salt in winter months take their toll. If not caught in time, a badly worn ball joint can even separate while driving. If it separates, a vehicle will lose control. You might have seen an older car with one of the front wheels collapsed under the vehicle. See the photo of a separated ball joint below.
Ball joints cannot be properly inspected during a "visual inspection." To check a ball joint, the front wheel has to be lifted off the ground, for example, when the car is raised on a hoist in a repair shop. In some trucks, checking ball joints is not a quick task: load-carrying ball joints, for example, must be unloaded to check them. Mechanics have specific instructions from car manufacturers on how to inspect ball joints and when a ball joint is deemed to be bad.
For example, a ball joint is usually replaced if it has excessive play or if it's loose. It's also replaced if the dust boot is broken or torn. Bad ball jointThis worn-out ball joint has separated. When a dust boot is damaged, grease can come out and water and dirt can get inside the ball joint. In either case, a ball joint won't last long. In some trucks, grease fittings serve as ball joint wear indicators. If a car has a bad ball joint, it's considered unsafe to drive.
It might also be a good idea to replace a ball joint as a precaution if it shows early signs of wear; for example, if it looks dry (lacks grease) or shows excessive rust damage. Corrosion damage is a major cause for ball joint failures. A ball joint that lacks grease may produce a creaking or squeaking noise when driving slowly over large bumps or when turning the steering wheel. Of course, several steering and suspension components can produce a creaking noise; the source of the noise must be diagnosed properly.

