These instructions apply to bearings in a non-drive wheel. In other words, if your car is front wheel drive, we're talking about the rear bearings. If it's rear wheel drive, you'll be replacing the front wheel bearings.
How do I know if I need new wheel bearings? Most of the time we don't even know that they need service. We just drive and never think about them. Most car manufacturers recommend a wheel bearing clean, inspection and repack every 30,000 miles. This is usually done along with the front brake service. They need to be replaced when there is scoring and pitting or they become noisy.
What you'll need:
Large adjustable wrench and Channelocks.
Bearing race driver tool or various size punches.
Socket and ratchet set or assorted wrenches.
Lots of rags.
New wheel bearings.
Wheel bearing grease.
New cotter pin.
New grease seals.
A jack and a pair of jack stands.
Rubber gloves (Optional)
Make sure that your car is parked on a level grade, rather than on any sort of hill or inclined driveway. Jack up the car and place your jack stands under the frame to support the vehicle. Block the rear wheels to prevent rolling. Set the parking brake and if you have an automatic transmission, put in Park.
A wheel bearing is a simple device made up of two main components, the bearing itself and the race. The bearing itself consists of a metal housing that is pressed over a row of ball bearings that circle the metal housing. These ball bearings in turn ride on the race, which is a very smooth metal surface. When a wheel is rolling, the action of the ball bearings rolling against the surface of the hub that allows the wheel to spin smoothly.
Wheel Bearing Problems
Problems with wheel bearings arise from wear, which can be caused by a variety of factors. Bearings are protected from dirt and debris by oil seals. If these seals fail and dirt finds its way into the bearing, damage can occur to the bearing and the race. Another factor can be long-term wear, affecting the bearings' ability to function properly. If a bearing falls apart completely, it can render the car undriveable and dangerous. The brakes will not function correctly and the wheel will not stay in its proper orientation.
Symptoms of a bad bearing are noisy rubbing as the car is driven and that usually gets louder as speeds increase. If the bearings are very worn, another symptom can be vague steering, vibrating suspension and darty behavior from the suspension as the wheel moves unevenly around the bearing.
Bearings can be checked by jacking up the car and pushing on the wheel. If there is excessive movement of the wheel on the spindle, it's probably the bearing. Wheel-bearing maintenance is relatively simple but time-consuming, since the wheel, brakes and hub need to be removed. Once the bearing is visible, check the bearings for wear and the races for any scratches or wear. Clean everything thoroughly and repack the bearings with a generous amount of bearing grease. This should be done every 20,000 to 30,000 miles.
Replacing bearings can be time-consuming, but most accomplished home mechanics can do the job. It involves removing the wheel, brake and hub. Once the hub is off, the bearing races are removed and new ones pressed in. This is usually the most difficult part. Once the bearings are packed and installed, everything is reinstalled in the reverse of removal. Refer to a workshop manual for detailed instructions about your car's model. This should be done every 40,000 to 50,000 miles.
A destroyed wheel bearing can result in a vehicle that is difficult to control. If you suspect that your bearings are bad, do not drive the vehicle until it is fixed or you know it is safe.