BMW 33127621206 Shaft Seal

Remove the final drive unit from the car and drain the oil, then unbolt and take off the rear cover plate. Hold each driveshaft driving flange still, unscrew the central bolts, and use a two or three-legged puller to remove the flanges. Mark the driving flange bearing cover/seal retainers according to which side of the final drive they are fitted, unbolt them, and retain the shims located under each bearing cover while renewing the bearing cover 'O' rings. Tilt the differential assembly to one side to project the taper roller bearing from the bearing aperture, then lift the crown wheel and differential out of the final drive housing. Mark the position of the driving flange to the pinion shaft, and using a cord wound around the pinion driving flange with a spring balance attached, determine and record the turning torque required to start the pinion rotating. Hold the driving flange still, relieve the lock plate, and unscrew the pinion nut. Apply pressure to the end of the pinion shaft to press it from the driving flange and roller bearings, then prise out the oil seal and press in a new one, ensuring it is flush with the final drive housing and filling the seal lips with grease. Fit a new collapsible spacer and reassemble the pinion to the bearings and driving flange, aligning it correctly with the previously made marks. Hold the driving flange still, tighten the pinion nut to 108 lb/ft (149.0 Nm), and check the turning torque of the pinion using the cord and spring balance; this should be the recorded figure plus 25% to offset the drag of the new oil seal. If the correct preload is not reached, tighten the pinion nut to a slightly higher torque wrench setting and recheck. If the preload of the pinion bearings is set too high, it cannot be reduced by backing off the pinion nut, necessitating the renewal of the collapsible spacer and repeating the adjustment procedure.

The pinion lock nut does not need to be disturbed when renewing the pinion oil seal on this design of the final drive unit, allowing the unit to remain in the car and minimizing dismantling to a few operations. First, disconnect the rear end of the propeller shaft. Next, unscrew the pinion driving flange nut and remove the flange using a small tool or three-legged puller. Then, prise the oil seal from its location and drive in the new one so that it is recessed by 0.24 in. (6.0 mm). Finally, apply grease to the seal lips and reassemble in reverse order.

Matchmark the flange lock nut with the threaded shaft.