How are Wheel hubs and hub bearings constructed?


THE wheel hub bearing is an integral part of the chassis. It is one of those elements without which the vehicle simply will not move. It is used for uniform, smooth, controlled rotation of the wheel by the drive shafts. Two types of bearings are used in modern cars: ball and roller bearings. They can have different designs, but mainly consist of:

Rolling elements (maybe cone or ball-shaped. They are used to transmitting forces from one ring to another. The rolling itself runs on the tracks of the 2 rings);

Crimp (holds the rolling elements);

Two rings (inner and outer).

Structurally, the rear hub bearing and the front hub bearing are practically the same, although different solutions are possible in different car brands and models. You can check wheel hub information from

To avoid friction inside the part, a special grease is used. Special protective sealing rings are used to prevent dirt and water from getting inside. Modern manufacturers produce maintenance-free bearings, that is, they can not be repaired. If they start to hum, they are replaced.

Bearings operate in very difficult conditions, withstanding heavy loads not only from the weight of the car, but also from the roughness of the track, temperature changes, resistance to car maneuvers (acceleration, turns, etc.), as well as water and other substances that fall on them from the road. How and when do I replace a wheel bearing?

These parts are made very durable. The bearing is designed for 200 thousand km mileage, but in life on our roads withstands no more than 100 thousand km.

The following signs may indicate that the bearing needs to be adjusted or replaced:

Accelerated tire wear or uneven degree of abrasion. Tire problems can be caused by faulty bearings. If you notice that the tires are wearing down too quickly, gently touch the wheel rim – it should not be too hot. Otherwise, you may be talking about a faulty bearing. The tires also start to wear more if the clearance increases or the nuts are not tightened properly.

The steering wheel does not turn well. If the wheel is running tight or there is a reduction in “run-out” (the angle of the axle in the longitudinal position), it is possible that the bearing is overtightened. To prevent the malfunction, simply watch the tightening torque of the hub nuts. Note that similar symptoms can be caused by the brake system or (for rear axle parts) bearings of differential or axle shafts – these are quite different elements.

You can see the wobble of the steering wheel. If there is wheel imbalance in the diagonal or radial direction, the bearing nut is loose and needs fixing.

Mechanical damage to the hub or natural wear and tear. Bearings can malfunction due to a defect in the hub itself – its seats or ribs. The first fault can be repaired by surfacing, followed by boring to restore the factory dimensional parameters. Cracks in the ribs can be repaired by welding.

Should the hub be replaced?

There are no specific maintenance requirements for this part in the technical information on vehicle operation. But it is important to change its components in time: replacing the rear hub bearing or replacing the front wheel hub bearing. This work will always depend on the broken part and the complexity of the work. No one will force a complete wheel hub replacement if it is not necessary, however, if it is not possible to perform the wheel hub bearing extraction and replacement, the part will still have to be replaced completely. This part is very strong and capable of breaking only in case of a serious accident, but this does not exclude the possibility of its warping, the appearance of other defects and natural wear and tear. But even in such cases, with minor damages, it is better to replace the front or rear hub to protect yourself, your loved ones and other road users, because the price of the component is much lower than the human life price. Replacing the hub of the front wheel is impossible to perform independently without knowing all the subtleties of the design of the car, and in particular, its running gear, which also applies to the replacement of the rear wheel hub.

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