Your Car's Ball Joints
The Pivotal Part of the System
You're in your car. Your hand is on the steering wheel and you're easing around a curve or bouncing on a bumpy road. You don't think much about the connection between your wrist movement and the movement of the front wheels of the car. But the connection is there, a system of rods, links, arms, joints, and spindles called the front suspension.
A pivotal part of this system is the ball joint, which operates something like the ball–and–socket joint in your hip. It has a round–head part that swivels in a cuplike cavity.
There are normally four of these ball joints in your car's front suspension, an upper one and a lower one for each front wheel. These durable devices can swivel smoothly for years without giving any trouble, in spite of dirt, mud, bumps, and jolts. Eventually they do get worn and the balls don't fit in the sockets as snugly as they once did.
The time may come when you take your car to the garage because it's making a funny noise, or it shimmies, or the steering is erratic, or the tires are getting scuffed because the front end alignment is off. What's wrong? Maybe the ball joints are worn, maybe not. How does the mechanic know, and how do you know?
Typical Front Suspension
There is a way to measure the looseness of a ball joint. California law requires that any time an auto repair dealer offers to replace one of your car's ball joints with a new one, the movement of the old ball joint must be measured with an instrument designed for that purpose. The measurement must be written on the invoice, along with a statement of what the manufacturer says is the maximum allowable wear or looseness of the old ball joint. Knowing these numbers, you can decide for yourself whether you want to have the ball joint replaced or not.
If your car has wear–indicating ball joints, a little measure boss or tab shows you when it is time to replace the ball joint.
If the car has mechanically adjustable ball joints, the dealer will adjust them according to the manufacturer's instructions.
Before any work is done on your car, the automotive repair dealer, by California law, will have to give you a written estimated price. You will be asked to authorize the work by signing a work order that states the repairs to be done, the estimated price, and the car's odometer reading. No additional work can be done, and no higher price can be charged, unless the dealer gets further authorization from you.
If you are not satisfied with how the repair job was handled, talk it over with the dealer. If you cannot resolve your differences, call the Bureau of Automotive Repair. The toll free number is 800–952–5210 (Local Sacramento number: 916–445–1254). Or visit one of the 12 district offices.
If your car is on the lift and the wheels can be wiggled, that does not necessarily mean that the ball joints are excessively worn. Rely on measurement.
- Be wary when a mechanic says, "I can't align your front end because your ball joints are worn." Try another alignment shop.
- Be alert to scare sales tactics. Don't be intimidated by the sight of somebody else's broken ball joint. Rely on the measurement.
- Remember, measurement must be made by a measuring instrument, such as a dial indicator, caliper rule, or a built–in wear indicator.
- Compare the mechanic's measurements with the tolerances given by the manufacturer.
- Replace ball joints when measurements indicate the ball joints have worn beyond the manufacturer's specified limits for safe operation.