Giunti sferici

Ball joints are pivoting ball-and-socket connections between the steering knuckle and the suspension control arms. They let the wheel move up and down with the suspension and turn left and right for steering at the same time. They are safety-critical load-bearing parts.

Each ball joint has a ball stud that swivels inside a socket, allowing movement in several directions at once. This lets the suspension react to the road while the wheels steer, keeping the wheel located correctly through both motions. Some joints carry the vehicle weight as load-bearing joints, while others mainly locate the knuckle.

The bearing surfaces wear and the grease can escape through a torn boot, letting dirt in. The first sign is often a faint, intermittent clunk from a corner of the vehicle, more pronounced over bumps or around corners, growing louder as wear increases, along with uneven tire wear and loose steering. Because a badly worn ball joint can separate and cause loss of control, worn joints are replaced promptly, often in pairs on an axle.

The correct ball joint depends on the vehicle model, the axle and suspension design, and whether it is a load-bearing or follower joint. Confirm the part against the vehicle specification before fitting.