What Are Bearings on a Car?

Bearings are one of your vehicle’s more critical parts, and bad bearings can significantly impact driving performance. However, since your car’s bearings are usually small and contained, many people don’t think about them or even know what they are for.

Wheel bearings are a part of every car’s drivetrain system. They have a significant impact on your vehicle’s performance, its safety, and even its environmental friendliness. How do your car’s bearings have that impact? Because the bearings in your wheels and drivetrain are there to reduce the friction in your drivetrain, they can significantly affect the all-around performance. It’s essential to know about this part so you can more accurately diagnose when there’s a problem. 

What Do Wheel Bearings Do?

Wheel bearings are designed to handle a lot of movement and vibration and work to reduce the friction and allow smooth movement within the wheel and moving connections of your vehicle’s drivetrain. Wheel bearings are the first primary connection point between the moving and stationary parts of your car. 

A wheel bearing is like any other bearing. The moving parts of a bearing are usually small round balls surrounded by lubrication. They are inside a housing chamber that protects the bearing and helps keep the lubrication from leaking or drying out over time. 

There are two kinds of bearings used in cars, ball bearings that have small balls inside the bearing as the primary rolling element, and tapered roller bearings that use small cylinders instead of perfectly round balls. 

Bearings are under a lot of pressure and can heat up thanks to your vehicle’s high friction. Bearings use high-quality lubrication to make sure they don't heat up too much or deform. The lubrication needs to be specialized for use in cars since it also needs to deal with its pressure and velocity while reducing the friction in the drivetrain as much as possible. 

Most car bearings are designed to be as maintenance-free as possible, and they don't need to be lubricated or have any other maintenance performed regularly. However, they can fail under stress, and you might need to get them replaced every once in a while. 

Wheel Bearings and Safety

The safety of your vehicle also depends in part on the quality and performance of your wheel bearings. Your bearings are essential for consistent performance and control. A bad bearing system can wobble or have uneven friction reduction, both of which can make it harder to keep your vehicle in control. 

Your wheel bearings also often send information to your ABS (Anti-Lock Braking System) about your wheels’ speed and how the wheels perform in different weather and road conditions. If your wheel bearings aren’t working correctly, your anti-lock braking system might get bad information and either engage when it isn’t needed or not correctly engage when you do. 

Wheel Bearings and Environmental Friendliness

The wheel bearings are also crucial for increasing your car’s overall efficiency and making it more environmentally friendly to drive. While you're driving, Friction is one of the most significant drag sources that can slow your car down. The bearings inside your vehicle's drivetrain work to reduce internal friction, which helps your engine perform better because there’s less resistance to keep your wheels from moving. 

Bad bearings can mean that your vehicle goes through gas that much faster since it’s working harder. But effective bearings can increase your MPG and make driving that much more environmentally friendly. 

Common Problems with Car Bearings

Wheel bearings don't have problems very often. It’s common for cars to go their whole lives without needing their wheel bearings replaced thanks to high-quality engineering and improved material quality. 

However, just because problems aren’t common doesn’t mean that you shouldn’t know what to look for when it comes to wheel bearing problems. Catching a bad wheel bearing sooner rather than later can save you a lot of money and heartache, especially since a bad bearing can lower fuel efficiency and even reduce the overall safety of your vehicle. Even slight problems can make your car more expensive to run and make it harder to safely operate your vehicle. 

The most common problem with car wheel bearings is a bad seal on the bearing. A leaking seal can allow the lubricant to escape, increasing the friction and heat inside the bearing. High heat can cause the bearing to deform and lose its proper shape. 

Leaking seals can also allow grit and other problematic substances into the bearing. Grit in the bearing reduces the effectiveness of the remaining lubricant. In the worst-case scenario, it can also start to damage the bearings themselves and the surrounding housing. As the bearing is damaged, metal filings mix with the lubricant’s original grit, making the problem worse. 

Water getting in through a weakened bearing seal can also cause serious problems. 

Wheel bearings can also wear out or go bad if they haven’t been installed correctly. That’s why new bearings often have a warranty to help protect consumers from bearing the extra costs of lousy installation. 

Your vehicle’s bearings are also vulnerable to damage while you’re on the road. The hardened steel is incredibly durable, so regular wear and tear usually won’t cause too much of a problem for the bearing. However, side collisions run a particular risk of causing bearing problems because the force’s direction puts a lot of pressure on the bearing’s weakest parts, risking deforming the bearing or breaking the internal seals. 

Signs of a Bad Bearing

Bad wheel bearings produce an audible sound. The louder the noise, the worse the problem probably is, in most cases. A bad bearing usually sounds a bit like a constant humming growl, and both the volume and the pitch of the growl will increase as the vehicle’s speed increases. Especially at highway speeds, you should be able to hear the bearing, and you might even be able to tell which wheel the sound is coming from. 

Bearings will also sound different when you’re turning and changing wheel directions because the sound of a bad bearing decreases when there is less weight and pressure on the tire the bearing is connected to. 

Sometimes a bad bearing will also cause more wheel play, where the car feels loose or unresponsive until you've oversteered the vehicle. 

If your mechanic mentioned that your tires are showing signs of uneven wear, a bad or failing wheel bearing can also cause the problem.