What is a Hub Assembly?  

Your wheel bearings and hubs are important parts of your vehicle's steering, suspension, and braking systems. Most modern vehicles use a one-piece hub assembly that incorporates the hub, wheel bearing, ABS wheel speed sensor, and mounting flange.

Wheel hubs connect the axles, steering knuckles, and the wheels.  They are imperative to the steering system because they help support the weight of the vehicle and help turn the wheels.  The wheel hub has a fixed part, the mounting flange, that mounts to and turns with the steering knuckle, along with a rotating part that contains the lug bolts and holds the wheel and brake rotor.  In the center of the rotating part of the hub is the wheel bearing. 

The axle fits into the bearing.  In a front wheel drive, or 4WD car, when your axle turns, it turns the bearing, which then turns the moving part of your hub.  The wheel and brake rotor held to the hub by the lug bolts and turns with the hub.  That's what allows you to accelerate or slow down your car's wheels.  In a rear wheel drive car, the front wheel bearing allows the wheel to turn freely. 

The front wheel bearings, along with the hubs, are important parts of your vehicle's steering, suspension, and braking systems.

Most modern vehicles use a one-piece wheel hub bearing assembly that contains the hub, wheel bearing, ABS wheel speed sensor, and mounting flange. Some vehicles use a separate bearing that must be pressed into the hub, usually requiring specialty tools.   

Front Wheel Bearing vs Rear Wheel Bearing Replacement

Front wheel bearings are the parts that connect your front axles to your front wheels, helping the axles turn the wheels smoothly.  The wheel bearing is in the center of the hub.  Modern wheel bearings are usually sealed units, with inner and outer rings, called "races," and ball bearings in between the two races.  The bearing is filled with grease and sealed with rubber. 

Like front wheel hubs, rear wheel hubs connect the rear axles to the brakes and the wheels.  Unlike front wheel hubs they do not play a role in steering, but if you have rear wheel drive or 4WD they connect the axles to the wheels to send power to the rear wheels.  Some vehicles, usually trucks don't use separate hubs, but have solid rear axles, which the wheels mount to directly.  

When Wheel Hub Replacement is Necessary

It's time to replace a wheel hub bearing if it starts to make noise, or worse if it affects your steering or ride.  Usually it's wheel bearing wear that leads to a hub replacement.  The wheel hub itself rarely has problems because it is made of solid steel.

Wheel bearings can fail because of age, dirt, and water contamination, or improper installation in the case of a two-piece hub and bearing assembly. Wear on the bearings rubber seals can let in dirt or water, which can hasten the wear of the ball bearings or the races.  That will make the bearing turn unevenly.  That uneven turning will usually first present itself as a grinding noise.  The noise usually gets worse as the car goes faster and when you turn to the side with the worn hub.  If left untouched, a worn bearing might eventually make your steering feel sloppy or cause "play" in your steering wheel. 

Another reason why a wheel bearing and hub assembly will need to be replaced is if an ABS sensor built into the hub itself and is not working. When this happens, even if you have a perfectly good working hub, the entire front wheel hub and bearing assembly will need to be replaced.

Why Are My Wheels Vibrating? 

One reason your wheels might be vibrating is due to a worn wheel bearing.  If the ball bearings inside the wheel bearing get worn, then they will make the axle turn unevenly.  That can make the wheel vibrate.  It might feel like you're driving over a rumble strip.  Often a vibration coming from a worn wheel bearing will get worse as your car's speed increases.  It also might get worse when you take a turn to the side with the bad bearing. 

How Much Does a Wheel Hub Replacement Cost? 

Wheel hub replacement costs can vary based on the model of your car and whether you have the work done by an independent mechanic or the dealership.  The cost for the hub itself can range from around $100 to as high as $600.  Labor costs might range from about $150 to about $400. 

Can I Replace a Wheel Bearing or Wheel Hub Myself?

Replacing wheel hubs or especially wheel bearings is usually a job that requires some automotive experience. In areas where vehicles are prone to rust, front hubs can be more difficult to remove. Use plenty of rust penetrating oil, and gather up as much patience as possible before beginning the job. If you have never replaced a wheel hub bearing assembly before, a service manual for your specific is useful.

Pressing in a wheel bearing is a precision job that can call for specialty tools.  If you need to press on a bearing, rather than installing a complete hub assembly, it's probably best to have the work done by a professional. 

How To Replace Wheel Bearing Hub Assembly

Here's a general overview of the steps in a typical front wheel bearing hub assembly replacement. 

1. Raise your vehicle and support it on jack stands. 
2. Remove your lug nuts and pull off the wheel. 
3. Remove the brake caliper.  Hang it from the frame with zip ties or a bungee cord to avoid putting strain on the brake lines.
4. Remove the brake caliper bracket. 
5. Pull off the brake rotor.
6. Remove the axle nut.  This usually requires the use of a breaker bar. 
7. Remove the bolts that hold the hub to the steering knuckle. 
8. Pull the old hub off. 
9. Lift the new hub into place and thread the bolts by hand. 
10. Tighten the hub bolts to your vehicle manufacturer's recommended torque setting with a torque wrench. 
11. Fasten the axle nut to the axle and tighten it to the recommended torque setting.
12. Slide on the brake rotor.
13. Put on the brake caliper bracket.  Install the caliper bracket bolts and tighten them to the recommended torque setting. 
14. Put on the brake caliper.  Install the caliper bolts and tighten them to the recommended torque setting. 
15. Slide on the wheel and thread the lug nuts by hand. 
16. Lower the vehicle to the ground. 
17. Tighten the lug nuts to the recommended torque setting.  

For an even more in-depth explanation of wheel bearing and hub assemblies, how they work together, why they fail, replacement tips, and more, check out our wheel bearings and hubs guide.