Replacing the main gear pinion seals (BMW 3 Series E21)

Removal

Remove the rear axle, drain the oil from the crankcase and install the axle on a repair stand.

Depending on the version, remove the locking plate installed in the center of the flange.

Measure the total torque of the bearings of the drive gear and driven gear using a dynamometer and a 30 mm diameter sleeve.



Use a center punch to mark the relative positions of the flange, its mounting nut and the end of the drive gear.



Holding the drive gear flange with a stopper 33 1 100, unscrew the flange fastening nut.



Press the flange off the drive gear using puller 33 1 150. After removing the flange, do not rotate the rear axle gearbox.





Using puller 00 5 000, press out the oil seal from the rear axle housing socket.

Installation

Fill the working edges of the new oil seal with consistent grease and press the oil seal into the axle housing socket until it stops using mandrel 31 2 040 and puller 00 5 000.

Using tool 23 1 300, press the flange onto the end of the drive gear in accordance with the marks made during removal and lock the flange.



Screw on the flange fastening nut and tighten it with a torque of at least 15 kgf·m so that the mark on the nut is shifted by 2 mm relative to the mark on the end of the drive gear. If the specified tightening torque of the flange fastening nut could not be achieved, and also in the case of turning the nut counterclockwise (when tightening, it is strictly forbidden to unscrew the nut), replace the compression sleeve after removing the pinion gear.



Lock the flange mounting nut by bending the tabs of the new lock washer.

Measure the total torque of the bearings of the drive gear and driven gear, which should be 50–70 N·cm higher than the value obtained before replacing the seal.

(The original source of the article is on the website «BMWMAN.ru»)