General Motors of Canada - Wheels, hubs and bearings are one of the most underserviced components on today’s vehicle.  Unless they fail, most drivers take them for granted and do not realize the true importance of having good wheel bearings.

Wheel bearings are designed to:

• Support the entire weight of the vehicle through the hub, wheel and tire
• Provide low rolling friction while traveling over the road to increase fuel economy and provide a smooth ride
• Withstand the extreme thrust (side to side and front to rear) loads generated by high-speed cornering, hard acceleration and braking
• Operate in extreme temperatures ranging from -20C on a cold start up to more than 200C during heave braking
• Operate in a hostile environment of road debris, splash, dirt, moisture and corrosion

How do I as a vehicle owner know that I need a new bearing?

• Worn wheel bearings usually cause excessive wheel bearing play that results in a growling or knocking noise to occur
• At first the knocking or growling will usually start to be heard only at a certain speed - i.e. 80km/H.  As the bearing wears out further, the noise will be constant and will become louder as wheel speed increases
• Worn wheel bearings can also cause excess pad-to-rotor clearance which can result in a low brake pedal, a brake squeal and/or clicking on disc brake vehicles.

Wheel bearing facts:

• A classic symptom of a bad wheel bearing is noise, so if a wheel is making “funny” noises when driving (squeaks, chirps, squeals, moans, etc.) or you hear a grinding noise when turning, it may indicate a bad wheel bearing.  Other symptoms include steering wander or possibly a pull to one side when braking
• If one wheel bearing has failed, pay close attention to all of the other hubs on the vehicle, too, especially if the vehicle has a lot of miles on it.  Chances are some of the other bearings may also be nearing the end of their journey
• There is no way to disassemble and repair a sealed hub assembly.  If the internal ABS sensor has failed or if the external ABS tone ring on the hub is damaged or badly corroded, the whole unit must be replaced.  The same goes for any other sealed wheel bearing and hub assembly.  If anything is wrong with it, the whole assembly must be replaced.  It cannot be rebuilt or repaired.
• A bearing failure can be dangerous because it may cause the wheel to separate from the vehicle and/or cause a loss of steering control!  It’s not something to ignore or put off because there is no way to know how many miles the bearings will go before the unit fails completely
• The other safety issue involved is the ABS system.  As long as the ABS warning light remains on, the ABS system is disabled.  This sound does not affect normal braking, but it will prevent the ABS system from helping out in an emergency or when braking on a slick surface
• On a vehicle equipped with anti-lock brakes and hub assemblies with an integral ABS sensor or tone, the ABS warning light will come on if a wheel-speed sensor is reading erratically or the signal is lost.  The ABS system will set a fault code that corresponds to the sensor location and disable the ABS system until the fault is fixed.  On these vehicles, the only way to get the ABS light to go out is to replace the hub assembly