What Causes a Wheel Hub Assembly to Go Bad?

Good wheel hub assemblies are built like tanks. But sometimes they break or wear out, like any other part on a car. When that happens, it’s easy to wonder what went wrong. There are three common causes of bearing failure: impacts, contamination, or improper alignment.

Wheel bearing hub

1. Impacts

Sometimes when your tire hits a pothole, curb, or another large obstacle hard enough, your wheel bearing gets damaged. The bearing either breaks or becomes weaker, leading to eventual failure. Is your car driving differently after hitting a pothole or something else? Your wheel hub assembly may have taken a beating and need inspection.

2. Contamination

Like all the components under the car, wheel hubs are continually exposed to water, dirt, dust, and other contaminants. They will corrode over time. Cars that live in cold climates are subject to salt and magnesium chloride. If you drive in the rain, some water may splash on the components in the undercarriage. But your wheel hubs get bathed in water. Wheel hubs are very exposed to the elements, so corrosion may cause problems sooner than it would for other components under the car.

3. Improper Alignment

The wheel hub’s job is to connect the axle and wheel and to allow the wheel to spin smoothly. Most of the time a vehicle is traveling in a straight line, which puts only minimal stress on the wheel bearing. If your vehicle is out of alignment and pulling, you have to constantly turn slightly to keep the car going straight. Then the bearing is under the added stress of a slight turn all the time. This causes the bearing to wear faster.

Wheel Hub Assembly Failure Symptoms

Whether you’re testing your own car or a customer’s car, you want to be able to detect the most common signs of a failing wheel hub assembly or a bad wheel bearing:

  • A grinding noise or rumbling sound
  • A clicking sound during acceleration
  • Vibrating or loose steering wheel
  • Abnormal side pull during brake application
  • Uneven rotor and brake pad wear

Easy access to the wheel hub assembly. Photo Credit: CJ Pony Parts

How to Diagnose a Failing Wheel Hub Assembly

If you notice these symptoms during your test drive, it can’t hurt to physically inspect each wheel hub assembly on the vehicle. To do this:

  1. Lift the car.
  2. Grab the wheel with both hands at the 12 o’ clock and the 6 o’ clock positions (top and bottom).
  3. Gently rock the wheel to see if there’s any noticeable play. (Note: In the early stages of bearing failure, this test may fail to detect the failure.)
  4. Remove the tire and wheel. Remove one slide pin and tilt the caliper so that the pads are not dragging on the rotor. (You may need to remove the caliper.) Spin the hub by hand, and pay attention to unusual resistance or vibration. Compare the hub to other hubs on the vehicle.
  5. Repeat with all the other wheel hub assemblies on the car.

In the early stages of bearing failure, you may hear the failure before you can feel it using techniques listed above. Another way to determine if the wheel bearing is failing is to measure the runout of the hub. Runout is a measurement of the amount of play in the wheel bearing. You need a dial gauge to precisely measure runout. The rule of thumb is that if the hub’s runout exceeds .004″, the bearing has failed.

Don’t forget to check the other components under the car! Worn ball joints and tie rod ends can cause symptoms like those caused by a bad wheel bearing.

The Key to Reducing Comebacks

No one likes comebacks, but they happen sometimes. You can reduce the number of comebacks your shop gets after a wheel hub assembly replacement with the three tips listed here.

If you’re looking for the key to reducing comebacks, it’s to use high-quality replacement parts. Installing a quality part means that there’s a low chance the customer will come back.

So what makes a quality wheel hub assembly? A few things:

  • High-strength steel
  • OE type sensors (to support proper ABS function)
  • Preloaded hub bearings
  • Premium triple-lip seals (to protect the bearings from contaminants)

When replacing a wheel bearing or a wheel hub assembly, be sure to:

  • Properly pack the bearing with grease
  • Use the manufacturer’s torque specifications
  • Use bearing-rated or manufactured-specified grease when packing a new wheel bearing
  • Install new seals

At GMB, we build premium wheel bearing and hub assemblies that fit all of the criteria listed above. You can’t go wrong with a GMB wheel hub assembly. Please contact us for more information about our world-class wheel bearing and hub assemblies.

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