Examination
With the vehicle raised and securely on stands, quickly rotate the rear wheels and check for bearing noise, turning resistance and play. Grasp the rear wheel with your hands in position «6 hours» and try to shake it in a vertical plane, while the allowable play is no more than 0.5 mm. If the play is large, it is necessary to check and adjust or replace the wheel bearings.
Front wheel bearings require disassembly of the front hub, rear wheel bearings can be replaced during routine maintenance.
Replacement
Raise the rear of the car and secure it on stands.
Remove the wheels and release the parking brake lever.
Using a chisel and hammer, remove the hub dust cap by tapping it around until it dislodges and can be removed.
Bend the shoulder and unscrew the hub nut. When installing, a new nut must be used.
Pull the hub block out a little and then put it back in its original position.
This operation should push the outer bearing and washer on the axle forward so that they can be removed with your fingers.
Remove the hub, place it on a suitable work surface and use a screwdriver to remove the bearing inner race.
Solvent remove all traces of old lubricant from the bearings, hub and axle. You can use a small brush for this, being careful not to get the bristles from the brush inside the support rollers. Dry the parts with compressed air.
Carefully inspect the bearings for cracks, wear, and uneven wear. Bearings and rings are one set, so new rings require new bearings. Similarly, when replacing bearings, new rings are installed in the hub.
To fill the bearings, use a high temperature lubricant that is packed between the rollers, the tapered surface and the bearing housing.
Apply a light coat of lubricant to the axle, bearing outer and inner surfaces, arm and gasket.
Press a small amount of lubricant into each bearing inside the hub. Form a layer at these points with your finger to provide additional lubrication and keep a thin layer of lubricant from running out of the bearing.
Install the grease-filled inner bearing into the hub and add some lubricant to the outside of the bearing.
Install a new gasket on top of the inner bearing, with the exposed lip facing toward the bearing, and press the gasket evenly into place.
Lubricate the gasket lug, install the hub assembly on the axle, and reinstall the grease-filled outer bearing and gasket.
Screw a new nut onto the axle and adjust the bearing preload as follows:
- tighten the nut to the initial torque specified in the technical data;
- turn the hub two or three times to install the bearing rollers, then loosen the nut one turn, while making sure that the brakes do not move;
Pic. 2.19. Measuring rear wheel bearing preload with a spring dynamometer
- attach a spring dynamometer to the top wheel stud and measure the moment at which the hub begins to turn (this value determines the resistance of the oil seal) (pic. 2.19);
- tighten the nut until the resistance (point at which the hub begins to turn) will not become 3.9–9.8 N·more than the seal resistance;
- Using a hammer and center punch, drive the collar of the nut into the groove of the axle.
Fill the dust cap with lubricant and install with a hammer and center punch.
Install the wheels and lower the vehicle to the ground. Tighten the wheel nuts.
Depress the brake pedal several times to correct the position of the brake pads, then check the parking brake lever travel and adjust if necessary.