If you hear abnormal and suspicious noise while driving, that might mean you’ll have to inspect your rear hub bearing. The noise appears due to wearing out. You should urgently get rid of them.
• Functions of rear hub bearing
• Rear hub bearing failures
• How to inspect rear hub bearing
Functions of rear hub bearing
Hub is very important part of any car. It has a hole for fitting components over axle. The main function of hub is passing of turning torque from bent shaft to wheel. Due to this the wheel turns and the car moves. The hub bearing plays no smaller part in work of running gear. The hub bearing features single-row or double-row ball antifriction bearing. They clutch together to provide maximum safety while driving. That’s why it is clear that any failure of bearing makes driving unsafe.
While hub bearings firmly fixate different units, they rotate. The main function of front and rear hub bearing is providing of reliable fixation and straight wheel rotation.
Construction is the difference between bearings of front and rear hub, but their functions are fully identical. Rear hub of independent wheel suspension is constructed almost in the same way as front hubs. The only difference is in axle swivel. Depending on suspension system, there are following types of bearings:
1) Radial ball or roller bearing if suspender is conventional;
2) Tapered roller bearing in case if suspender is independent.
ny type of rear hub bearing is exposed to wearing out. The reasons can be different.
Rear hub bearing failures
The main problem that may occur with rear hub bearing is wearing out. There are several premises for it and they are various: excessive load, low efficiency of sealing, too small lash because of large interference in seating.
Third of car bearings fail because of normal wearing out. Another third breaks down because of low quality grease. The rest part of bearings fails because of dirt, incorrect exploitation or installation. The specifics of car exploitation allow to separate several reasons of bearing failure:
1) Bad blurring of mounts. Greasing substances can “degrade” because of excessive heating of bearings, damaged weatherstrips, use of incorrect oil or poor quality material for blurring of mounts of hub bearings.
2) Bad bearings. The similar problem is involved penetration of water and dirt. Abrasive compound forms after penetration.
3) Tear Wear. The first signs of fatigue damages depend on amount of load, rotation rate of the element, purity of greasing and efficiency of its application. Wear can appear and develop because of changeable shifts in the upper layers of bearing races, that’s why the cracks appear, which locate in the direction of the surface. Rolling elements roll in cracks and parts of metal of bearing break off. Initially this process, which is called “peeling” or “pitting”, do not show. But “peeling” constantly develops and increases because of edged tensions and wear products, which contain in greasing.
Process of fatigue “peeling” of bearings elements develops too slowly, accompanies by increasing of vibration and noise level in operating time. Due to these signs you can notice this problem and change the bearings before they wrack. Remember, the damages do not appear because of too thick layer of greasing substance in comparison with size of surface irregularities. Because of excessive load to the bearing, natural fatigue break-down will develop soon.
How to check rear hub bearing
As articulated earlier, existence of damaged bearing can be determined by excessive noise, appearing during driving. You can define the rear hub bearings condition turning them to the left and right. At turn to the left, the body roll carries over to the right side. So, load passes from the left wheel on right and conversely. If you turn the hand wheel to the left at speed of 10-15 km/h and noise disappears after that, it means the noise proceeds from the left wheel, to be more exactly, from the bearing of the center boss. If the noise disappears at right turn, you will have to change the bearing of the right wheel.
To conduct more exact diagnostic, you should lift the car by the elevator or hand crew. Then run the engine, “turn up” the car to speed in 70-80 km/h on the fourth gearing, depress the clutch and switch off gearing. You should aurally define, what wheel makes noise. If the wheel is not tractive, you can twist it by hands. When the wheel stops, you should take the upper part by one hand and the lower part by the other hand. Try to rock the wheel in vertical plane. Even if there is small endfloat, be sure, you will have to change the bear. Try to loosen the wheel in horizontal plane. Take left and right parts of the wheel and try to rock it.
It happens that endfloat appears because of malfunctions of suspension members or wear of steering system. Ask somebody to press by force the brake pedal and try to roll the wheel vertically at the same moment. If the endfloat do not disappear, you should seek for reason in the suspender. If the endfloat disappears, the reason is in hub bearing.
Remember one principle – if the hub bearing is in good repair, there must be no endfloat. When you find out the reason, you may drive away the car to specialists in service or change the bearing in your own hand. When you change the bearing, you should keep cleanness, expose the gap during conic bearing installation, it is undesirable not to use sharp tools, which can damage the sealing strips.
To prolong bearings’ life to the maximum, you should keep rules of mounting and service. Operating time of these details depends on rule of choice of element and use correct tool for its mounting. Do not the bearing in dirt or water, it must be correctly greased and installed. During installation keep the following recommendations:
1) Extract the bearing from packing before installation.
2) Keep cleanness: close those details of the car, on which the bearing is put, cover new bearing, which you do not install, by film, paraffin paper or clean dry fabric.
3) You should not install the bearings near metal-cutting machines or equipment, which creates pollution.
4) Do not deliver blows to the bearing.
5) Use special bush to press the bearing.
6) Use correct greasing substance. Apply it in necessary quantity. Grease bearings in time.
7) Use special hydraulic or heating tools.