Understanding the Wheel Hub Assembly

There’s more to owning a car than driving it. From time to time, your vehicle will need some form of maintenance to keep it in tip-top shape. Sure, you can drive your vehicle to your car manufacturer or local auto mechanic to have it serviced but there will be times when your vehicle will come across unintentional forms of car trouble. It could be a breakdown on the side of the highway or an inability to start in the early winter mornings. 

It can be frustrating when these situations occur. Understanding how your vehicle works and maintaining it reduces the risk of these failures. Proper maintenance guarantees a car’s safety,  reduces future car repairs, and ensures reliability to keep your vehicle on the road for as long as possible.

Your wheel hub assembly is one of the most crucial parts of your car. This article will explain what a wheel hub assembly is, pinpoint identifiable symptoms of bad wheel bearings, and provide tips on what to look for in high-quality part replacements.

What Is A Wheel Hub Assembly?

The wheel hub assembly, or hub assembly, is the part of the vehicle that gets the car from point  A to point B. While their more famous “cousins”  (the tires, brakes, struts, or suspensions) get the most attention, wheel hub assemblies are the tireless workhorses of your vehicle.

Found behind all four wheels, between the brake discs and drums and the drive axle, the wheel hub assembly supports the entire weight of your car, providing a hassle-free and smooth ride. Most importantly, it helps keep the tires attached to your vehicle. The hub assembly may be low maintenance, unlike its more glamorous fellow spare parts, but when it does get worn down or need replacement, you’ll know it immediately.

Housed inside the wheel hub assembly are the wheel bearings.

A set of engineered steel balls, the wheel bearings enable the wheel to spin with as little friction as possible, allowing the vehicle to move forward or in reverse. Housed in sealed metal rings called a race, wheel bearings are lubricated with heavy multi purpose grease to work.

Although wheel bearings last for 85,000 miles to 100,000 miles, you should check and maintain your wheel bearings every 25,000 miles to 30,000 miles. Any mechanical spare part that rotates, rolls, and rubs just as much as the wheel bearings do can run the risk of wearing out faster than other components. Luckily, issues with the wheel hub assembly or its  bearing are immediately noticeable.

Indicators of a Worn Out Wheel Hub Assembly

Noise is one the most identifiable symptoms of a worn out wheel hub assembly. As the wheel bearings are housed in sealed rings with sufficient dose of lubricants, any consumed amount  in the wheel bearings can increase the friction between the steel  balls or rollers. If foreign objects such as sand, dirt, or little particles of metal enter the wheel bearings, noise will occur. The most common sounds you will hear are cyclic noises such as growling, rumbling, a whine, or a  moan.

Another typical indicator of a worn wheel hub assembly is a loss of steering control and your vehicle feeling less responsive or pulling in a certain unintended direction. If your vehicle has the tendency to wander or you feel a pull in the steering wheel, that could be a significant indicator that your wheel hub assembly needs replacement.

Uneven tire wear is also a clear sign that your wheel bearings and hub assembly are failing. When wheel bearings start to fail, they loosen in their housing, giving your wheel a slight wobble. If your tires look damaged despite regular maintenance, this can mean worn out wheel bearings.

How to Maintain Your Wheel Hub Assembly

One of the quickest ways to determine the issue that lies with your wheel hub assembly is to jack your car up in the air and spin the tires by hand. If you feel any roughness or excessive drag, then that could show bad wheel bearing  failure. Your car’s manual will tell you the right amount of movement that is acceptable.

Your ABS warning light will also serve as a good maintenance tool to determine if your hub assembly will need replacement. Any vehicle with anti-lock brakes may have speed sensors attached to the hub assembly. Worn wheel bearings interfere with the sensor ring’s functionality, leading to the appearance of your ABS warning light. Diagnose your ABS with a scanning tool to confirm that the problem is your wheel bearings.

Excessive drag produced by worn out bearings creates a hub assembly that runs hotter than those which are running. By checking the temperature of the hub assembly, you can determine which assembly is worn out.

Buying or Replacing Bearings

If you do intend to go DIY on your wheel hub assembly and its bearings, instead of bringing it to a trusted mechanic for servicing, here’s what you need to look for in quality bearings.

As the wheel hub assembly plays such a crucial role in your car’s performance, avoid the idea of being penny-wise and pound foolish. Cheap bearings made of low quality steel and poor heat-treating engineering can fail prematurely. Buy your bearings from trusted bearing manufacturers and invest in quality seals to ensure protection from external contamination and guarantee adequate grease containment. It is also recommended to always replace your axle nuts instead of reusing them.

It’s also very important to find the recommended replacement bearings for your vehicle as outlined in your car’s manual. Each vehicle requires different bearings for its brand, model, and year of manufacture. Likewise, it is best to buy the recommended bearing grease to protect and lubricate  your wheel bearings which is usually located in the vehicle service manual.

Proper maintenance of your wheel hub assembly gives you a no-hassle and smooth driving experience. Functioning wheel hub assemblies help ensure that your vehicle runs efficiently for years and help limit its  depreciation if you ever decide to resell it. Whatever the case, well-maintained hub assemblies keep you and your vehicle safe on the road.


Hassanein Alwan is the Marketing Director for Mineral Circles Bearings with more than 10 years’ experience in the bearing industry’s technical support division, sales and marketing, plus  expertise in strategic business development consultancy.

With a degree of Master of Science in Engineering from KTH Royal Institute of Technology and an International Diploma in Business from the University of Cambridge, he started his career in Sweden as a Machine Safety engineer for Gröna Lund and as SAAB Aerosystems’ Aeronautical engineer. Today, he serves as a member of the Know Your Market Committee after joining EPTDA in 2013.