Ball joints allow the front wheels of a vehicle to move up and down, protecting them against road bumps and allowing you to turn while steering. Over time, ball joints in a machine can wear out. If a joint begins to loosen, you will hear strange sounds coming from the front as if the joint is rattling. If it tightens, the steering will cause friction and you will feel some resistance as you turn the steering wheel. Fortunately, a quick and easy check can be done before serious steering or suspension problems occur.
Steps
Part 1 of 2: Control of Swing Arm Vehicles
Step 1. Look for a wear indicator
While the vehicle is still on the ground, look under the car, at the bottom of the joint attached to the wheel. The most common indicator is a grease fitting that doubles as a wear indicator. This fitting, or boss, protrudes from the bottom of the joint housing about half an inch (1.25 centimeters). With wear, the fitting recedes into the housing. As long as the garment sticks out, the joint should be ok. If the fitting is flush with the body or has shrunk even further, the ball joint must be replaced.
If you can't find a wear indicator, or if the indicator doesn't give you a clear enough signal, lift the car up to inspect the joint further
Step 2. Lift the front end of the car
In some cases, the manufacturer recommends placing a jack under the lower control arm of the front wheel, as close to the ball joint as possible, then jacking up the vehicle until the wheel leaves the ground. If you don't do this, the joint will still be under tension when you lift the machine, making it difficult to move and find play on the joint.
Make sure there is no compression on the suspension when checking the ball joint. If you have control levers of different lengths, make sure the top suspension stop does not touch the control arm
Step 3. Spin the reels and check the game
Make sure the car is raised securely, preferably on jack stands. For side-to-side play, place a dial gauge inside the rim near the ball joint. Grab the wheel on both sides (3 and 9 o'clock) to push it and pull it out to the side.
- For vertical clearance, place the dial gauge against the steering knuckle nut or ball joint housing, depending on the manufacturer. Grab the wheel on the top and bottom (12 and 6 o'clock) to raise and lower it.
- Read the comparator and check the results with the manufacturer's specifications. If movement is beyond specification, replace the ball joint.
- Experienced mechanics can check play without special tools, listening intently for unusual noises or movements that indicate joint wear. Alternatively, you could have an assistant look closely at the joint itself to see if it appears loose as you move it.
Part 2 of 2: Controlling Vehicles with the Suspension Strut
Step 1. Look for the grease fitting
If your front suspension uses McPherson struts, look for that wear indicator, which is usually a grease fitting. Grab the fitting and try to move it. If the fitting is too loose inside its housing, the ball joint needs to be replaced.
Step 2. Lift the car onto the front crossbar
Many front-wheel drive cars with strut suspension should not be raised using the lower control arm, so it's a good idea to consult your owner's manual before attempting to examine the joint. In general, you should lift the car as usual, onto the frame post.
If you have McPherson struts, allow the strut to extend as far as possible before checking wheel play
Step 3. Use a lever or other tool to control the play from the top to the bottom of the ball
Generally, it is not easy to move the ball joint with your hands alone, but you can use a lever or even a long screwdriver under the wheel to lift it and then see if the ball joint needs to be replaced.
Step 4. Listen
The ball joint in a strut-strut vehicle should make a slight snap when you move it up and down, and you should easily tell if it's worn and not working as it should. If you notice excessive play when moving the pry bar, the ball joint needs to be modified.
