Wheel Bearing: how it works, symptoms, problems

September 14, 2015
Wheel Bearing
Wheel bearing for a front-wheel drive vehicle.

Most modern cars have four double-row ball wheel bearings; one for each wheel. This type of a wheel bearing is greased and sealed at the factory. It doesn't need any maintenance or servicing. If it fails, it is replaced as a unit.

A wheel bearings holds the wheel hub, as you can see in this photo. As you know, the wheel hub is the part that the wheel is attached to.

Wheel bearing problems

CV Joint boot looks OK
Technician checks a wheel bearing for excessive play

The two most common problems with wheel bearings are when they become noisy or have excessive play felt in the wheel.

Let's start with the first problem. A wheel bearing can become noisy as a result of normal wear or corrosion. Hitting a curb or a large pothole as well as a collision involving one of the wheels can also result in a noisy wheel bearing.

A worn-out wheel bearing can also cause excessive play felt in the wheel. To eliminate excessive play, serviceable roller bearings can be repacked with new grease and adjusted. In the same situation, a sealed maintenance-free wheel bearing will have to be be replaced.

Is it safe to drive with a bad wheel bearing? The answer is no, if the wheel bearing is bad, the vehicle is unsafe. An extremely worn-out wheel bearing can overheat, seize or disintegrate while driving.

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Symptoms of a bad wheel bearing

Bad wheel bearing produces a humming or growling noise

The usual symptom of a bad wheel bearing is a humming, growling or roaring noise that gets louder with speed. See the video.

Often a wheel bearing noise gets louder when the vehicle changes direction, for example, on a twisty stretch of the road or when exiting a highway.

In many cases it's difficult to say which bearing is noisy as the noise travels through the car body or frame. To pinpoint a noisy wheel bearing your mechanic may have to run your car on the lift while listening for the bearing noise using a mechanic's stethoscope.

Wheel Bearing Replacement

The price for wheel bearing replacement ranges from $180 to $340 per wheel. If only one wheel bearing is bad there is no need to replace other wheel bearings. However, in some cases, a vehicle may have more than one noisy wheel bearings. In this case, all noisy wheel bearings must be replaced. Is it difficult to replace a wheel bearing as a DIY project? In some cars, a wheel bearing is bolted to the hub assembly (knuckle) in others it's pressed into the hub. If the wheel bearing is bolted in, like for example, in 2009 Nissan Rogue or 2006 Ford Explorer or 2014 Mazda 3, replacing it is fairly easy. On the scale from 1 to 10 such a job will rate as a 6 or 8. If the bearing is pressed in, you may want to have it changed in the repair shop, as pressing the old bearing out and new one in is difficult without a special press or special tool.

Tapered roller bearing

Some pickup trucks, vans and SUVs as well as some older cars have roller-type bearings installed as a pair at one wheel. Roller-type bearings do need periodical servicing that includes repacking with new grease and adjusting the bearing preload. How can you tell what type of wheel bearings are in your vehicle? The adjustable roller-type wheel bearings usually have a protective steel cap (marked with arrow) that seals the grease inside the bearing.

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