Auto Repair Q&A



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Bad Wheel Bearings

Wheel Bearing

Diagnosing wheel bearing problems is relatively simple. In most cases, lifting the car and spinning the free tire(s) to watch for wobbling or shuddering. On many vehicles, especially smaller cars, grabbing the wheel on opposite sides and wiggling left-right and up-down, can tell an experienced mechanic if there is too much give in the wheel. Removing the tire and wheel can allow for a better test along these lines, since it removes the possibility that the wheel or tire are to blame.

Symptoms of bad wheel bearings include grinding sounds, wobbling while on the road, drifting to right or left when in a straight line, and uneven tire wear. Bad bearings should be replaced quickly as they can lead to much bigger problems as they progress and finally fail entirely.

Once a bad bearing has been diagnosed, replacement is the order of business. Most mechanics tend to replace bearings in pairs, so if the bearing on the front left wheel has gone bad, replacement of the front right is also often recommended. This is to keep the bearings "even" and to eliminate the likelihood that the opposing bearing will begin going bad due to age and/or extra pressure from the opposing bad bearing.

The procedure for each vehicle is slightly different, but in general, replacing wheel bearings is the same on all cars and trucks. If you have a competent repair manual or service manual for your vehicle, you'll find wheel bearing replacement details there.

We are assuming here that you are familiar with basic shop safety and are following safety guidelines.

With the vehicle on a flat surface or positioned on a shop lift, remove the wheel from the affected hub where the bad bearing is located. Lift the vehicle.

On axles where disc brakes are installed, remove the brake caliper and disc. For drums, remove the outer drum. Place these safely to the side (tie the caliper up and away). Most hubs will have a dust cover that is now exposed. This looks like a little cap and can be removed with a flat headed screwdriver or hub removal tool.

A castle nut and cotter pin (or set of pins, depending on the vehicle) are now exposed. Remove the cotter pin carefully and make sure you have a replacement pin that is the same size. Using a breaker bar or similar, remove the castle nut and its associated washer.

Remove any items that are now blocking the hub assembly. These may include the rotor guards, the brake rotor itself, or the back of the drum brakes on some vehicles.

On many vehicles, the hub bearing is not replaced itself, but instead the entire hub assembly is replaced. If this is the case, remove the assembly and replace it, then put everything together again. If not, you'll need to disassemble the hub assembly to get to the bearings.

On most vehicles in which this is possible, you'll need to remove the anti-lock brake wheel and use a special puller to remove the center bolt. The bearings should then be easy to remove. Most vehicles will also likely have "bearing races," which must be removed and replaced as well.

Using shop rags, carefully clean out all of the hub grease and grime inside the hub and around the steering knuckle. Liberally replace that with new axle grease before placing the new races and bearings inside. Having too much is not an issue, but having too little lubricant is. Carefully "pack" the bearings in and keep adding axle grease until you cannot possibly get more inside. Then begin reversing the procedure to put everything back together.