Inspection and Adjustment of Tightness of Automobile Wheel Hub Bearings

The tightness of the steering wheel and the wheel bearing of the middle and rear wheels directly affects the performance of the car. If the wheel bearing is too tight, the wheel rotation resistance will increase, the friction loss will increase, the sliding performance will be reduced, and the bearing will be easily damaged; if the wheel bearing is too loose, the wheel will sway during rolling, causing tires and related equipment. Unusual wear and tear of parts. In particular, if the wheel bearing of the steering wheel is too loose, the steering wheel clearance will increase, and the steering sensitivity and driving stability of the vehicle will be reduced. Therefore, in the maintenance of automobiles, attention should be paid to the inspection and adjustment of the wheel bearing tightness.

The general adjustment method of the bearing tightness of the wheel hub is: after the outer bearing of the hub hub is in the correct position, turn the hub hub while screwing the bearing adjusting nut into the bearing adjustment nut until the hub hub feels very tight by hand. Back the adjusting nut another 1/6-1/4 turn and tighten the lock nut. When adjusting the rear wheels of Yanan 250, Tatra 148 and Nissan TKL-20, the above method is commonly used, but the number of laps after tightening is different for Tatra and Nissan; some cars, such as Isuzu TDJ and For SJR type vehicles, when adjusting the tightness of the rear wheel hub bearing, the bearing adjusting nut should be screwed inwards, and the nut should be slowly unscrewed until it is very laborious to rotate the hub hub. Hang a spring balance on the wheel bolt of the wheel, and pull the wheel along the tangential direction with a force of 2030N (with the brake drum installed), it is appropriate to just pull the wheel to rotate. If it is a new bearing, the pull force should be 70-90 N. When adjusting the tightness of the wheel bearing of the steering wheel, the adjusting nut must be tightened first, and the test is carried out with a pulling force of 200-300 N. When the wheel is just able to be pulled to rotate, stop screwing in the nut, and turn the wheel left and right for 2-3 circles. , Loosen the adjusting nut until the wheel can be pulled to rotate with a force of 10-25 N; Check its axial clearance or the force required to pull it to start turning, and make corrections as necessary. For example, for the Mercedes-Benz 2026 car, it is stipulated that the adjusting nut should be tightened with a torque of 300 Nm, then the nut should be loosened by 1/8 turn, a thrust washer should be installed, and the locking nut should be tightened with a torque of 500-550 Nm. , check the axial clearance of the hub. This gap should be in the range of 0.03-0.05mm. If the gap does not meet the requirements, it should be adjusted again until the gap is suitable. For another example, when adjusting the tightness of the ift bearing of the front wheel of Nissan TKL-20, the adjusting nut should be tightened with a torque of 400 Nm, and then the nut should be loosened by 1/1/2 after turning the wheel for 2-3 turns. 6-1/4 circles, turn the wheel again for 2-3 circles, and then use a spring to measure the tension of the wheel v when it starts to rotate. The tension should be adjusted to 55N; for some models, it is not only required to tighten and adjust with a certain torque Nut and lock nut, and it is stipulated that the adjusting nut is tightened and loosened twice each, and the tightening torque and the number of turns of loosening are also different. For example, Hongyan 261 car, when adjusting the tightness of the steering wheel hub bearing, first tighten the adjustment nut with a torque of 500 Nm, then loosen the nut by 1/4 turn, and then tighten the adjustment nut with a torque of 100 Nm , then loosen it back 1/8 turn, then install the lock ring, and tighten the lock ring’s fastening bolts to a torque of 25 Nm. When adjusting the wheel bearing tightness of the middle and rear wheels, first tighten the adjusting nut with a torque of 600 Nm, then loosen it by 1/6 turn, and then tighten the lock nut with a torque of 800 Nm.

Although there are some different methods for adjusting the bearing tightness of the wheel hub, no matter which method is adopted, it must be ensured that when the wheel hub is rotated by hand after the adjustment of the bearing tightness, the wheel hub rotates. Flexible, no sticking phenomenon; when the wheel is pushed and pulled along the axial direction by hand, there should be no shaking; during the road test, if the wheel is touched by hand, there should be no burning sensation; during driving, the wheel should not swing. Otherwise, it means that the wheel bearing is too tight or too loose, and the adjusting nut should be loosened or tightened appropriately.