Hub Unit Bearings: Features, Maintenance, Installation & Removal

Hub Unit Bearings: Features, Maintenance, Installation & Removal

Hub units are gaining increasing acceptance in automotive applications, resulting from the integration to various levels of the bearing wheel hub and knuckle assembly.

Hub unit bearings have to meet increasingly strict requirements that demand lighter weight, greater promotion of fuel efficiency, and enhanced module production systems. Along with the widespread adoption of antilock braking systems (ABS) to ensure stable maneuverability during braking, there is a growing need for our hub unit bearings with a built-in sensor. ISUTAMI offers a range of high quality hub units with ABS sensors.

On the course of development of hub units, there appears three different generations: The first-generation hub unit (Hub I), second-generation hub unit (Hub II), and third-generation hub unit (Hub III). These three generations vary according to the integration of the bearings and their peripheral components. Below we will discuss the features of the three generations.

Maintenance is the key factor to the life span of hub units. Hub unit bearing maintenance generally means keeping them lubricated. This service is done by removing the wheel bearing from the wheel hub assembly, greasing it manually or with a device called a wheel bearing packer, and then reinstalling it. Some vehicles do not have removable wheel bearings. The wheel bearings are sealed in the hub. In this case, you will need to purchase a new wheel hub bearing.

If your vehicle requires periodic wheel bearing maintenance, it is essential you keep to the maintenance schedule. Over time, the grease in your wheel bearings can breakdown and become less effective. Also grease can escape through the bearing until there is not enough left to lubricate the bearings.

Without proper lubrication, the wheel bearings could overheat. When that happens, your wheels could fall off. (This is unlikely, and will only happen in extreme cases when the wheel bearing problem has been ignored.)

Warning signs include a wobbly wheel or a low growl or hum coming from any of your wheels. In either case, you should replace your bearings yourself, or take our bearings to a local repair shop.

The following are some advices on removing and installing hub unit bearings properly to enhance the performance and longevity of hubs and benefit the axles and wheels, if you wish to replace the bearings yourself.

Hub Unit Bearing Removal
1. Begin by raising the vehicle up and removing the lug nuts and the wheel.
2. Remove the brake caliper and rotor. The caliper should be supported and not hanging freely.
3. Next, the axle nut needs to be removed using an axle nut socket. The vehicle manufacturers instructions should be used to determine proper nut replacement.
4. If possible, disconnect the ABS sensor wire from its mating connector point. This is usually located in the wheel well or on the chassis frame. Also, disconnect the sensor wire from the clips that are used to properly position the sensor wire in the wheel frame. Before removing, be sure to make note of the current orientation and positioning of the sensor wire and bearing.
5. Remove the bolts that attach the bearing to the steering knuckle. A puller may be needed to remove the hub assembly from the knuckle. Be careful not to damage the knuckle or axle shaft.

Hub Unit Bearing Installation
First, insert the new hub assembly into the steering knuckle. Check the positioning of the splines on the axle shaft as the hub assembly is inserted into the knuckle. Carefully position the two components so the splines are not damaged during the installation. Never force the hub assembly on the shaft and never hit it with a hammer or other tool.
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