You’ve taken your car to your local mechanic and he has informed you that you need new wheel bearings. You may think your mechanic is just trying to drum up some extra repair costs because your car still runs fine.
Let’s delve deeper into what wheel bearings are and why they’re so important.
What Is A Wheel Bearing?
When you take off your car’s rim and tire, you may have noticed a nut or cap in the center of the wheel. If you continue to remove the brake disk or drum, you’ll be left with the part that is connected to the lug bolts which hold your wheels on. This part is known as a hub. Removing the cap and bolt from the middle of the hub, allows us to take the hub off. Squeezed in the back of the hub is a large metal ring. This ring is your wheel bearing.
While most newer cars have sealed wheel bearings, older models have an open bearing you can see the inside of. The wheel bearing consists of an inner ring with a channel on its outside. On this channel, a series of small metal balls sit, as well as sitting on a second channel on the inside of the outer ring. The outer and inside rings are referred to as a race and are usually connected.
Your wheel bearing connects the wheel and axle and is designed to allow your car’s wheel to spin as fast as possible with as little friction as possible while keeping the ride comfortable. If you still cannot visualize it, How Stuff Works have cut a wheel bearing open.
Signs Of A Failing Wheel Bearing
Unlike a lot of parts on a car, your wheel bearings won’t just suddenly break, they’ll give you several signs that they are beginning to fail.
Signs to look out for are noise and vibration. If you hear a humming or growling noise when turning or accelerating, that’s the first sign of wheel bearing failure. When wheel bearings are getting really bad, they begin to sound like grinding and whining. Some people have even reported their wheel making helicopter-like noises.
If your steering wheel vibrates excessively, the initial response is to believe your wheels need to be balanced. If the vibration continues after checking the balance of the wheels, it’s a sign that the bearing is beginning to break because it’s no longer balanced.
Leaving your wheel bearings unattended too long can cause the entire wheel to lock up while moving.
How Do Wheel Bearings Break?
Wheel bearings need to be lubricated. All lubrication ages with use and becomes less effective as part of regular wear and tear. As the lubrication ages, it allows for more friction to begin to build between the bearings and the race, which creates heat. More friction can lead to the bearings failing to turn properly and eventually break. Heat causes the race and bearings to expand, and contract when they cool off. This cycle causes the race to crack.
Bearings also have a seal with the hub that keeps foreign contaminants out. If the seal is damaged, either from use or poor installation, or the race is cracked, dirt and water can get into the wheel bearing, and cause the lubricant to denature prematurely, and bearings to rust to the race.
Other factors that can lead to wheel bearing failure is impact damage from rough roads, or fitting heavier rims to our car because they increase the load that acts upon the bearings and increases the friction between the bearings and the race, so extra caution should be taken when choosing a new rim.
Wheel bearings are an important part of keeping any vehicle safely on the roads, and replacing damaged ones should not be delayed and addressed by a professional.