3 Things Students at Auto Mechanic College Should Know About Wheel Bearing Maintenance

Car mechanic worker repairing suspension of lifted automobile at auto repair garage shop station

Wheel bearings are a critical component of a vehicle’s drivetrain, serving to reduce friction, and to connect the static and moving parts of a car. As part of the hub assembly, wheel bearings are an important element of a vehicle’s steering, braking, and suspension systems, working in tandem with the brake disc or drum, the ABS wheel speed sensor, and the mounting flange. They make the rotation of the wheels possible, allowing them to roll instead of slide, and also enabling them to turn smoothly. 

When wheel bearings are not properly maintained, there are a few things that can go wrong. Here’s what mechanics should know about the maintenance of this important car component.

1. Mechanic Program Students Should Know that Roller Wheel Bearings Must be Greased 

The most important thing that auto mechanic college students should know about wheel bearing maintenance is that all wheel bearings need to be properly greased. Axle grease allows the rollers and the races to work together by preventing metal-on-metal contact, and absorbing the heat created as a result of friction. When wheel bearings are properly greased, they produce the critical rolling effect, keeping the wheels from sliding. Additionally, grease prevents moisture from contaminating and rusting the bearings. The grease used is a long-fibre, high temperature variety, made specifically for wheel bearings.

Roller wheel bearings require occasional re-packing

From time to time, the grease used in wheel bearings may need to be re-packed. This is only necessary in roller bearings, which are typically not fully sealed and are more susceptible to contamination. Mechanics should recommend that vehicles with roller bearings are taken in for inspection about once a year. Contaminants from the road such as salt, mud, water, or sand penetrate the seal of the wheel bearings. When repacking the bearings, it’s important to clean the inside of the hub as well as the bearings, races, brake hardware, and seals before reinstallation. During the re-packing process, the bearings should be checked for signs of wear such as pitting or rough spots, as well as overheating. While roller bearings can be re-packed and serviced, ball bearings typically require full replacement if the bearing seal is damaged or leaking. Below are some ways to tell that ball bearings need replacement.

2. How to Tell if Wheel Bearings Need Maintenance

While roller bearings can be taken in for preventative maintenance and re-packing, this luxury is not available for ball bearings. These bearings don’t typically require regular service as their sealant is designed to keep all contaminants out. However, if there is a strange noise coming from a vehicle’s tires or wheels, this could be a sign that the sealant has been damaged or is leaking. This noise can be described as grinding, squealing, growling or grating, and can be especially loud when a vehicle accelerates. If there is a noise coming from the ball bearings, this is a sign that they need replacing, as the damage has already occurred. Noise can indicate that the bearings are worn out. Worn out bearings are caused by a lack of lubrication, which occurs when water or other contaminants permeate the seal and prevent the grease from doing its job.

Contaminants such as mud can cause a vehicle’s wheel bearings to wear out

Another indication of worn out wheel bearings is uneven tire wear. If one tire is wearing out more quickly than the others, the wheel bearings are probably worn. Drivers should also suspect a wheel bearing issue if their steering feels less responsive, or looser. When wheel bearings are worn down, they can loosen within a vehicle’s wheel bearing assembly. It’s important for students in a mechanic program to know that when a vehicle is experiencing any of these symptoms, it’s probably time for a wheel bearing replacement. 

3. The Consequences of Wheel Bearing Damage Can Be Severe

Worn out wheel bearings can cause damage not only to a vehicle’s wheels, but also to its constant velocity joint or automatic transmission. The constant velocity joint is connected to the transmission and attaches the wheels to the drive shaft. If the wheel bearings are worn out, the issue can cause problems for these car components. When damage is suspected, it’s important that drivers take their wheel bearings in for service immediately in order to stay safe on the road.

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