Hello Paul, a friend mentioned wheel bearings. What are they and how do they wear out? Can they affect safety if ignored? Esther Nankya
Hello Esther, wheel bearings or hub bearings are components fitted in the knuckle or wheel carrier. They are designed to allow your wheels to rotate easily with little friction while carrying the weight of the vehicle. Wheel bearings are positioned in the wheel hub assembly. They are designed to carry the stress of constant loads, road shocks, and high rotational speeds. Wheel bearings help to support the vehicle weight, facilitating free spinning of wheels while reducing friction.
Wheel bearings also keep the wheels aligned to ensure vehicle stability and good handling. Although wheel bearings are designed to last many years, over time they need to be replaced due to a few factors. During operation, wheel bearings succumb to normal wear and tear due to high mileage.
Contaminants that penetrate the wheel bearing casing such as water, mud, or dust will eventually cause failure. Wheel bearings can also be damaged by sudden stress or impact when you drive fast over potholes, hit road curbs, or after a collision during accidents.
Poor installation or failure to tighten wheels correctly during repairs can lead to a wobble which damages wheel bearings. An overloaded vehicle also stresses the wheel bearings as they carry weight beyond their design limit, which leads to premature failure.
There are a few signs which can help you tell that your car’s wheel bearings are worn out. As you increase speed, you may experience a humming, grinding, or growling noise which steadily increases as you drive faster.
Shaking or vibration sensation can be felt in the steering wheel or vehicle body at certain speeds when the front or rear axle wheel bearings are worn out. Damaged wheel bearings can also cause uneven tyre wear. This can be corroborated during garage inspection if the mechanic detects uneven tyre surface wear when the wheel is rolled on the floor.
Wheel bearing wear can also be detected by a mechanic when they rock the wheel and detect excessive sideways play. In some rare cases, worn out wheel bearings can cause the ABS warning light to appear on the dashboard. This is because many modern cars have the ABS wheel speed sensors integrated with the wheel bearings, while most of them read notches that are built on the wheel bearing casing. A damaged or incorrectly spinning wheel bearing will distort ABS sensor readings and cause the ABS fault light to display.
Worn out wheel bearings can affect car handling and road safety by reducing steering precision and vehicle stability. Bad wheel bearings lead to abnormal tyre wear and increased braking distance or reduced performance.
Worn out wheel bearings can also damage the hub assembly due to overheating. Occasionally, severely worn out wheel bearings will cause excessive wheel wobble and, in extreme cases, lead to catastrophic separation of wheels from the vehicle, a very dangerous situation.
It is highly recommended that you have your car inspected at a garage when you detect bearing noise or excessive wheel play. Consider replacing a worn wheel bearing as early as possible to avoid further costly damage or a compromise of your car handling and road safety.