Ball joints carry upward and downward load-bearing stresses that affect the way the car handles and turns. Comfort and ride can be a direct result of the condition of the ball joints; worn or dry ball joints can cause unnecessary binding in the steering control, heavy handling and jarring rides. Without correct functioning front end parts like ball joints, safety and stability can become concerns that sooner or later lead to major repairs. Worn ball joints show some outward signs that a vehicle owner can notice if he knows what to look for.
Ball joints have a ball and cup design that rotates and flexes in all degrees of arc, governed by the demands of the suspension. Lower ball joints typically carry the front end weight and receive the most stress. When ball joints wear they can twist the tyres off the centre line, allowing them to seat off-angle in the cups. This can wear the tyres dramatically, either on the inside or outside. Inside wear happens most often when the suspension actually sags. Excessive ball joint wear can cause a noticeable pull of the vehicle in either direction while on a straight and level road surface.
Manufacturer's tolerances and specifications
A certified repair facility or front end alignment shop can tell you if your ball joints have exceeded maximum allowable tolerances. By using a dial indicator with the chassis loaded (on the floor) they can determine the exact horizontal play in the ball joint seat. Generally speaking, a reading of more than 1.3 mm (0.050 inch), measured at the drive axle nut, can be considered beyond normal limits, but not in all cases, since different models and makes might have higher tolerances. This accurate measurement technique can apprise you of your need to replace the ball joints.
Ball joint shoulder depth indication
Ball joints with wear indicators have a raised collar at the base of the ball joint grease fitting that sticks about 1.3 mm (0.050 inch) out from the joint base. As the joint wears, the shoulder sinks into the joint. When flush with the joint or having receded into it, it indicates the ball joint base has worn away. This check can be performed visually by the vehicle owner.
Wear indicator pins
Some ball joints have wear indicator pins that protrude through the bottom of the ball joint to show how much wear has been sustained. Simply measuring the length of the pin provides an accurate reading of how much material has worn away. When the pin has reached the surface of the ball joint or disappears within it, it is past its useful function and should be replaced.
Grease fitting play
Chrysler front-wheel drive cars have a grease fitting that becomes progressively loose as the ball joint wears. It can be checked by wiggling it with the fingers. Excessive movement means that the interior joint assembly has worn and must be replaced.
Worn ball joint noises
Worn ball joints can make a variety of mechanical noises. A squeaky noise, akin to a rusty hinge sound, can be heard with the up and down movement of the front end suspension. Ball joints that have run dry can bind, giving off a metallic grinding sound while turning. Fractured ball joints can emit a clanking sound when the vehicle goes over driveway lips or parking stops. All noises of this nature coming from the front end should be investigated.