Wheel bearings allow the wheels on your car to rotate with minimal friction and support your car's weight. Most rear wheel bearings are engineered to last about 150,000 miles but sometimes they fail prematurely thanks to poor adjustment, contamination or loss of grease. If you want to keep your car running properly, you'll need to keep your rear wheel bearings in near-perfect condition.
The first symptom of bad rear wheel bearings is usually noise. You might hear rumbling, growling or chirping coming from the vicinity of your rear wheels. Once you hear this noise, you need to take your car in to have it serviced immediately. Expect the amount of noise your rear wheel bearings are making to be proportional to the speed you are driving, whether you are accelerating, coasting or decelerating. The noise might sound different while you are making turns or disappear at some speeds entirely. Most bad rear wheel bearings are identified when drivers complain about this noise.
Bad rear wheel bearings may also result in play. Play can allow steering wander. This means that although you are holding your steering wheel still, your car drifts to the left or right as you drive. Play can be dangerous for drivers, especially on highways. Play reduces the amount of control you have over your vehicle. If your rear wheel bearings are sealed and they play, that is a sure sign that they need to be replaced. If the rear wheel bearings are adjustable, you or your mechanic may be able to adjust the bearings after removing, cleaning and inspecting them. Play is usually a sign that your rear wheel bearings are worn, but it could also mean that the hub nut backed off or the bearings were not properly adjusted.
Turn Your ABS Light On
If your anti-lock brake system light is on and you can't for the life of you figure out why, check your rear wheel bearings. If your car is equipped with anti-lock brakes and sealed hub assemblies with an integral anti-lock brake sensor or tone ring, the ABS light will come on if a wheel speed sensor is reading erratically or has no signal. The anti-lock brake system will set a fault code corresponding to the sensor location and disable the anti-lock brake system until the fault is fixed. The only way to fix this is to replace your hub assembly. You can't repair a sealed hub assembly and must replace the entire unit.
Cause Your Car to Lose Its Wheels
In the most extreme of cases, ignoring your bad rear wheel bearing can cause your car to lose a wheel. One of the rear wheels on your vehicle may fly right off while you are cruising down a highway, placing everyone in its path in danger. Losing a wheel on a freeway while travelling at high speeds could result in a deadly accident. Thus, if you have any reason to believe that your rear wheel bearings are bad, you must immediately take your car to a mechanic to have them examined.