How long should a wheel hub assembly last?

Q:  “When should I replace my wheel bearings?”

A:  Eventually, all wheel bearings wear out and will need to be replaced. Assuming normal service under typical driving conditions, the newer, “hub-assembly” style bearings found on most modern vehicles should last around 100,000 miles when maintained properly. The older style bearings might last just as long but it’s a good idea to start having them checked regularly once they reach about 60,000 miles.

In performance applications or on modified cars, as is the case with this Porsche 944 Turbo pictured here, you can expect the “life-span of the wheel bearings” to be significantly shorter. The wheel bearings on the drive wheels weren’t meant to be able to handle the throughput of increased horsepower that heavily modified cars achieve over the factory stock configuration. Furthermore, the wider wheels and tires that are often fitted to modified cars in order to accommodate that increased power and transfer it to the road are also extremely hard on the wheel bearings.

Q:  “How Do You Know if Your Wheel Bearings are Bad?” / “Signs and Symptoms of Wheel Bearing Failure”

A:  When they initially begin to fail, wheel bearings first begin to get loose. This allows the wheels to “wobble” slightly as they roll down the road, which leads to “uneven tire wear”. This looseness, or “bearing play” is usually too subtle to be felt through the steering wheel, at least at first. As the wear increases, the bearing’s ability to mitigate or limit friction becomes increasingly compromised and heat generated from that increased friction will begin to build up.  It is at this point when the decline in bearing integrity speeds up dramatically, and when the first noticeable signs of “wheel bearing failure” become apparent to the driver. When the heat becomes great enough, the grease lubricating the bearing will burn away, further increasing friction and heat. At this point the driver can usually feel “grinding” and some “pull in the steering wheel”, but by far the most common symptom is the “howling noise” coming from the bearing as the car is driven (sometimes described as a “whining noise”). The faster the speed, the louder it gets. After all of the bearing grease is lost, the friction of metal on metal will rapidly build up heat, eventually reaching the point of being hot enough to even soften the steel. Once the wheel bearings have worn to this state, it is critical to have the issue addressed by a qualified auto shop. (We could probably recommend one…)

Wheel bearings are low maintenance parts, but that doesn’t mean they last forever. So, what does a wheel bearing actually do? How long does it last? And how can you help extend its lifespan?

What is a wheel bearing? And what does it do in a car?

A wheel bearing is a crucial part of the wheel assembly that connects the wheel and the axle. It is a set of steel balls (ball bearings) or tapers (tapered bearings), held together by a metal ring. It enables the wheel to rotate smoothly with a minimum of friction. Wheel bearings are safety critical components designed to sustain radial and axial loads caused by gravitation, acceleration, breaking & cornering forces, so they need to be replaced when they stop working properly.

How long does a wheel bearing last?

Wheel bearings have an average lifespan of 136,000 to 160,000 km (approximately 85,000 to 100,000 miles). This is only a rule of thumb though, the actual lifespan of a wheel bearing depends on the quality of the wheel bearing and the operating conditions.

Why do wheel bearings fail?

The main reasons that a wheel bearing fails are:

• Faulty installation – inappropriate tools such as a hammer or an impact wrench can cause damage to the exterior and or interior of the wheel end bearing causing the wheel bearing to fail prematurely.  Also, re-using the old accessories such as bolts, nuts, circlips, split pins, seals,… instead of replacing them with new ones can cause the wheel end bearing to operate under abnormal or unsafe conditions, increasing wheel end bearing wear and risk of a car accident. 
• Impact damage or poor road quality – all impacts from driving through a pothole, driving over speed bumps or hitting the curbstone can damage a wheel bearing and reduce its lifespan.
• Poor quality wheel bearing – a wheel bearing is continuously under enormous pressure. Wheel bearings constructed of low-quality materials can have poor heat-treatment, resulting in premature wear and failure.
• Driving conditions – driving through deep water or mud can cause your wheel bearings to fail. Water, mud or other contaminants such as dust or road salt could get past the seals and enter the bearing, polluting the grease and wearing away the bearings.
• Car modifications – fitting bigger or wider rims, tires with lower thread walls, stiffer shock absorbers and suspension springs cause higher loads on the wheel bearing and can accelerate wear. Stick to rims, tires, shock absorbers and springs that are specified by the car manufacturer to minimize the impact on the longevity of the wheel bearings.

What are the symptoms of bad wheel bearings

The symptoms of bad wheel bearings include:

1. Noise:
   • A humming, rumbling or growling noise that increases with acceleration or as the vehicle turns.
   • A loud constant whining or grinding noise when the vehicle is in motion.
   • Clunking noises when driving over uneven road surfaces.
2. Looseness, excessive play in the steering wheel (vague steering);
3. Steering wheel vibration which changes with the vehicle speed or as the vehicle turns;
4. ABS malfunctioning. ABS system issues can be related to failure of the ABS sensor that is integrated in the wheel end bearing. 

What are the risks of driving with bad wheel bearings?

It’s very rare for wheel bearings to fail immediately and completely after you notice the first symptom(s). 

Having said that, it is best to avoid driving with a worn wheel bearing for any length of time. As we’ve already seen, the wheel bearing is essential for connecting your wheel to your car, and any weakness in this connection could have severe consequences for your drive-axle and steering assembly – as well as for your safety.

Replacing your wheel bearings

Despite the fact that modern wheel bearings are easier to install than previous generations, correct installation, the usage of appropriate tools and respecting the specified torque values are still essential for maximum performance, durability and safety. Therefore, we recommend having your wheel bearings fitted by a professional mechanic that has the skills and the tools to do the job.  

Quality replacement parts

When replacing your wheel bearings, it is essential to look for high quality parts. MOOG offers a complete range of easy to install, premium quality, long-lasting wheel end bearings that are engineered, manufactured, tested and validated to OEM standards for maximum performance and durability.
Explore the full MOOG product range or
Discover technical tips about wheel bearings.