H What are Wheel Bearings?
Would you believe that bearings have been around since the ancient Egyptians built the pyramids? The logic behind a wheel bearing is quite basic: Things will roll better than they slide. When something slides, the friction between them will slow them down. However, if the two surfaces rather roll over one another, friction is significantly reduced. The ancient Egyptians achieved this by placing round logs under heavy stones to roll them to a building site. The reasoning for bearings in your car – or any machine for that matter – is the same.
Wheel bearings are low-maintenance parts, but they don’t last forever. What do wheel bearings actually do?
Your wheel bearing is a critical part of the car’s wheel assembly, connecting the wheel and the axle. It is a set of steel balls (called ball bearings) or tapers (tapered bearings or rollers) that are held together by a metal ring. They are made using high quality and high spec steel. The inner and outer races – rings with a groove where the balls or rollers rest – and the rolling elements, rollers, or balls, are heat-treated. The resulting hardened surface adds to the wear resistance of the bearing.
Wheel bearings enable the wheel to rotate smoothly with the minimum amount of friction. They are safety-critical components that are designed to sustain radial and axial loads caused by gravitation, acceleration, braking, and cornering forces. For this reason, they need to be working properly at all times.
Signs of Bad Wheel Bearings
Your wheel bearings’ lifespan will depend on the manufacturer’s quality, your day-to-day operating conditions, and driving loads, but they are expected to last at least 75,000-100,000 miles. The most common reasons a wheel bearing will fail are:
- Faulty installation: using the wrong tools can damage the bearing and re-using old bolts, nuts, pins, and seals can cause the bearing to function unsafely.
- Impact damage such as a collision or hitting a pothole
- Poor manufacture quality or low-quality materials
- Driving conditions such as mud or water
- Contaminants such as road salt or dust
- Modifications to the car’s rims, suspension, and shock absorbers.
How will you know that your wheel bearings need maintenance? Here are six signs to be on the lookout for:
- Strange sounds: You may hear sounds like humming, whirring, rumbling, grinding, or clicking coming from the wheel area.
- Uneven tire wear: Worn ball bearings will start to loosen within their housings, causing them to lose some effectiveness and cause uneven tire wear.
- Vague steering: Your steering feel may feel loose. Faulty bearings can create some play within your wheel assembly, causing your steering to feel more vague than usual.
- Wheel lock: Modern wheel bearings are sealed primarily to prevent dirt, debris, or other contaminants from getting to the bearings and reduce lubrication, thereby increasing friction. Less lubrication and more friction cause overheating, and the bearings could lock up or grind. When the bearings lock up, the wheel could lock up too – causing serious danger.
- Vibration: If your wheel bearing seal is worn or broken, it could lead to a rougher drive and vibrations.
- Traction control or ABS malfunctioning: Modern cars wheel hub assemblies are equipped with sensors that inform the traction control, ABS, stability control, as well as other driver-assistance systems. If a part of the wheel assembly like the bearing is not functioning properly, it could cause these systems to malfunction.
Ball Bearings vs Roller Bearings
The most common types of wheel bearings are ball and roller bearings. Rollers are basically a series of small cylinders placed in a tapered circular housing. Roller bearings are not normally sealed, which makes them good for service but susceptible to contamination. Ball bearings use little balls with small contact points for rolling ease. Ball bearings are generally sealed, which helps keep contamination out, but often can’t be serviced.
Bad wheel bearings need to be replaced. When replacing bearings, it is best to do them all at once to ensure even and balanced driving. The wheel bearings normally come as part of a larger wheel hub assembly package, making it rather an involved job.
Remember that a car with bad wheel bearings might be drivable, but it is not recommended to drive with a bad wheel bearing. If you notice one or more of the symptoms above and suspect a bad bearing, immediately get your car home or to the repair shop. In a worst-case scenario, the wheel could lock up while you are driving, making driving with a bad wheel bearing potentially very dangerous. If a wheel bearing fails, it can even cause the wheel to fall off. A failed wheel bearing can cause serious damage to your car, so it is crucial that you keep an eye on these and keep them maintained.
If you are wondering how long the repair will take, it varies from vehicle to vehicle as well as the skill level of the mechanic and which wheel bearing needs replacing.
If it is a rear-wheel bearing, it will probably take between 15 and 45 minutes. If the hubs and wheel bearing are permanently bolted to the car it may take 20 to 60 minutes. Front-wheel bearing replacement will take between 30 and 60 minutes, depending on the mechanic.
When it comes to 4-wheel drive vehicles or rear axle bearings on rear-wheel drive, it can take hours. Not surprising, considering that it is a bigger job.
It is worth mentioning that wheel bearing replacement can be quite costly due to the parts and the substantial labour costs. For this reason, some people choose to do the job themselves. DIY is not recommended unless you have mechanical experience, as you can cause more harm than good.
To sum up: if you suspect a wheel bearing failure, stop driving on it immediately. Take it to your mechanic straight away. Feel free to ask your mechanic any questions about your wheel bearings because it is always better to prevent a problem rather than react to it.
A full-spectrum auto service workshop in Cambridge, ON , Special Interest Automobiles is proud to have been serving Cambridge automobile owners since 1985. Give us a call today and leave your vehicle’s wheel bearing maintenance to our professional auto service team.