Despite being a significant component of your vehicle’s drivetrain, wheel bearings often get overlooked. Only a few people, most of whom are technical individuals, could attest to this claim.
Situated in the center of your wheels, inside the hub assembly are your wheel bearings. Wheel bearings play the important role of supporting the entire weight of your vehicle while driving and ensuring the moving and static areas of your vehicle are friction-free.
To effectively perform a friction-free movement, the right multi-purpose automotive grease must be used. A well-lubricated wheel bearing improves the performance of your wheels and, as a result, your vehicle.
Without the right lubrication, wheel bearing failure can occur. Driving with a faulty wheel bearing is dangerous. Without a well-lubricated wheel bearing, your wheel can fall off, which can put you and other drivers on the road at risk.
Bearing assembly basics
Before we delve deeper into lubricant selection, it’s important to understand how wheel bearings work and how to identify tell-tale signs of a faulty wheel bearing.
Wheel bearings you’ll typically find in the hub assembly are ball bearings and tapered roller bearings.
Ball bearings are the most common and feature perfectly round spherical balls. The ball bearings’ spherical shape enables these to handle radial loads (weight of the car) and thrust load (sideways force). While these are the most versatile bearing type, ball bearings have very small contact area.
This makes them more suitable for light-to-medium applications such as skateboards, household machinery, or electric motors.
Tapered roller bearings use conical rollers that are cylindrical. The unique design of the bearing assembly allows this “tapered cone” to handle heavy amounts of high radial and axial loads as well as hard shocks. Tapered roller bearings are typically found inside the wheel hub.
Other components that can be found in the wheel bearing assembly are:
- Race — A metal ring that surrounds the bearings
- Bearing cage — A special type of metal cage that holds the bearings together inside the bearing assembly
- Bearing seal — An O-shaped round seal used to keep lubrication where it’s needed and to protect bearings from foreign contaminants
- Bearing snap ring — A rigid circular metal band that keeps the roller bearing assembly secure
- Wheel hub — Houses wheel bearings and serve as the mounting assembly for the wheel of a vehicle
Symptoms of a bad wheel bearing
Like all mechanical components, wheel bearings are subject to wear and tear.
And over the length of your vehicle’s life, your wheel bearings will eventually be replaced. The best way to know when it’s time to replace wheel bearings is to understand the warnings of a faulty wheel bearing.
The easiest way to tell when a wheel bearing has gone bad is by the sound it emits. Audible noise is the most easily identifiable symptom of a worn wheel bearing.
Clicking, snapping, or popping are some of the most common noises you’ll hear coming from wheel or tire. These noises are typically heard during sharp turns or cornering. Grinding while shifting or turning is another audible indicator that your wheel bearing needs replacing.
Another way to tell that your wheel bearing is faulty is through your vehicle’s steering. A lack of responsiveness or looseness from the steering wheel can also be a revealing sign of a worn wheel bearing. The sensation of pulling can also point to wheel bearing damage as the culprit.
Alternatively, you can check your tires. If your tires show abnormal or uneven tire wear, your wheel bearings may be loose or are faulty.
It should be noted though that these symptoms are also often caused by other wheel assembly components. A worn suspension can produce uneven tire wear similar to the symptom above. Likewise, loose steering can be another problem associated with the wheel assembly.
Have your vehicle inspected by an automotive professional to confirm the cause of any wheel assembly and to ensure that issues will be promptly addressed.
Understanding wheel bearing lubrication
Once you’ve noticed the symptoms above, chances are, your wheel bearings will need replacement. Even if there are no noticeable symptoms, bearing manufacturers recommend inspecting, cleaning, and repacking wheel bearings every 30,000 miles.
If you’ve decided to do the repair job yourself, you need to have a bit of a technical knowledge to know what’s the right bearing lubricant to use.
Different types of lubricants can be used in specific cases as they differ in some aspects like viscosity and their composition.
Grease is more commonly used in applications that operate at moderate speeds and temperatures. Its synthetic formula means grease consists of base oil and a thickening compound. These thickeners are primarily metal soaps like aluminum, organic compounds, or inorganic compounds.
Types of wheel bearing grease include:
- Multi-purpose grease
- Ion-based grease
- Moly EP grease
- Disc and drum bearing grease
- Marine wheel bearing grease
The inclusion of additive types like anti-corrosion and antioxidants further fortifies its performance. This protects from contaminant ingress. Certain characteristics can also enhance the capabilities of grease, enabling it to withstand high-pressure and high-temperature conditions.
The best grease for your bearings will be dependent on your vehicle’s manufacturer.
Wheel bearings affect your vehicle in more ways than you know. Because of its significant role in vehicle performance, understanding how wheel bearing assemblies work and how lubricant types function differently will ensure that your vehicle’s wheel bearings are maintained in optimal condition.
Hassanein Alwan is the Managing Director of Mineral Circles Bearings with more than 10 years’ experience in the bearing industry’s technical support division, sales, and marketing, plus strategic business development consultancy.