What can Happen when Wheel Bearings Fail
Automotive wheels use roller bearings, either in the form of ball bearings, tapered roller bearings, cylindrical roller bearings or spherical roller bearings. The rollers maintain their position by being sandwiched between inner and outer metal rings called races. Depending on the design, one of these races—inner or outer, will be in contact with the not rotating chassis, and the opposite race will be the contact point with the rotating portion of the wheel assembly with the rollers between allowing the movement to take place. For a detailed web tutorial on bearing construction and design by an industry leader visitthis link.
What is meant by wheel bearing failure is that the surfaces of the rollers and of the races have become less perfect and resistance to roll is increased, usually indicated by a humming sound or growl during rotation of the wheel while driving as well as increased temperature—where there is friction there is heat. Also, as a result of the deformation of the surfaces, the races and rollers are no longer being held in their designated position, which is indicated by abnormal tire wear, less precise steering response and feedback and “play” or “sloppiness” in the wheel’s orientation to the chassis.
Once the bearing has begun to wear at all, the rate at which it continues to wear compounds. The increased friction and heat increases the rate of wear, which increases friction and heat, and so on. As the wear becomes more significant and the wheel falls further out of correct alignment, the tire tread wears faster and the brakes begin to wear unevenly. Brake components are engineered to perform at the specific geometry of the wheel being in correct alignment. There is a decrease in fuel economy and additional suspension components become strained. Ball joints, tie rod ends and strut assemblies are all components that maintain wheel alignment and are designed, like the brakes, to perform within certain geometric limits. As the wheel falls further out of correct alignment due to bearing wear, these components operate at the limit of their design and will perform poorly and wear towards failure quickly. This is a safety hazard.
Furthermore, many later model vehicles that are equipped with anti-lock braking systems have a sensor integrated into the wheel bearing assembly to measure rotational speed. As the bearing wears, the alignment of the components informing the ABS computer is thrown off and results in erratic ABS system behavior or non function of the feature and may present as a warning indicator lamp on the dash board.
While the components that keep a vehicles wheels on the car are well engineered, the possibility of losing a wheel while operating a vehicle with wheel bearings that are worn beyond acceptable safety standards exists! Once a wheel bearing has been identified as worn, it should be replaced immediately in order to avoid the costly compounding of having to replace additional components and the possibility of catastrophic failure which is not only a hazard for the operator and passengers of the vehicle in question, but of all on the road, and near the road, around it.
