Pinion Bearing: Service and Repair

Replacing Bearing For Drive Pinion (Type K)
Final Drive Removed

Remove final drive, refer to 33 10 010.





Secure final drive to special tool 33 1 010.
Drain off fluid.
Take off case cover.

Installation:
Replace seal.
Tightening Torque, refer to Technical Data 33 11 1AZ.

Topping up oil.
Oil fill quantity, refer to Technical Data.
Oil grades, refer to BMW Service Operating Fluids.





Press off drive flange with pry bar.





Installation:
Before fitting the drive flange, the round wire circlip (1) must be placed in the groove of the differential housing in such a way that both ends of the round wire circlip are recessed.
This prevents lateral bending of the ring. Press in drive flange by hand and turn slightly until wire snap ring is heard to engage. Replace stretched snap rings.





Punch mark both bearing caps.
Unfasten screws on both bearing covers and remove bearing covers (turn if necessary, because the sealing ring grips firmly suction).

Caution: Do not mix up bearing caps and spacers.

Secure spacers on bearing cap with a piece of wire, if necessary.

Installation:
Tightening Torque, refer to Technical Data 33 11 2AZ.





With shims (1), the axial preload of the differential bearing (4000 N) and the torsional face runout of the crown and bevel gear is set. (2) = O-ring





Remove complete differential case.

Caution: Do not bend the pulse generator wheel.





Remove lockplate.





Brace input flange with special tool 23 0 020 and unfasten collar nut.





Remove input flange with special tool 33 1 150.
The specified friction torque level is indicated for the new bearing.
Refer to Technical Data.
The friction torque of the old bearings no longer needs to be measured.





Press out drive pinion.

Caution: Be careful not to damage threads.





Extract front outer bearing race with special tool 33 1 350.
(1) = Spreader
(2) = Outer bearing race front
(3) = Puller bell housing
(4) = Pressure bolt





Remove rear outer bearing race with special tool 33 1 351 / 356 / 362 / 363.

Caution: The shim (X) is located below the rear outer bearing race.

This is needed again to adjust the block dimension.
Measure and note down thickness of shim (X) e.g. X = 4.10 mm.





Install old shim (X) in front of rear outer bearing race.
Draw in new outer bearing races with special tool 33 1 373 / 365 / 362 / 363 / 354.





Pull bevel gear roller bearings off drive pinion with special tool 33 1 300.





Press new taper roller bearing onto drive pinion using special tool 33 1 020.

Caution: Always only use same make bearings for both.





To determine the correct shim (X), the drive pinion is installed with new taper roller bearings and no clamping bush.





Install drive pinion in the rear bearing outer race.

Draw front taper roller bearing onto drive pinion with special tool 23 1 300 in conjunction with a spacer bush.





Mount input flange.

By carefully tightening down the collar nut, adjust friction torque of input taper roller bearing to 250 Ncm.





Caution: When tightening down, keep checking friction torque with special tool 00 2 000 at regular intervals.





Secure dial gauge in special tool 33 1 481.

Fit special tool 33 1 481 with dial gauge on special tool 33 1 482 and set dial gauge preload to zero.

Fitting special tool 33 1 482 to drive pinion.

Install special tool 33 1 481 in housing.

Read value (Y) and note down e.g. Y = 1.92 mm.

Example:






The correct thickness for the shim is 3.90 mm.

Caution:
If the difference (D) is positive, the old shim was this much too thick.
If the difference (D) is negative, the old shim was this much too thin.
The permitted tolerance for the shim (A) is derived from the available shim gauges which range from 0.01 ... 0.03 mm.





After determining the shim thickness (x), remove drive pinion.

Caution: Note make of bearings - this is required to determine the friction torque.





Remove rear outer bearing race and install with a shim (x) of the appropriate thickness.





Install drive pinion with a new clamping sleeve (2).





Immerse shaft seal in final drive oil and drive in flush with special tool 33 1 430 in conjunction with special tool 00 5 500.





Press-fit input flange to the input shaft using special tool 23 1 300 but do not tighten down.

The axial preload force of drive pinion bearings (5000 N) can be determined with help of the friction torque.





Gradually tighten down input flange with collar nut, measuring friction torque at regular intervals.





Measure friction torque with special tool 00 2 000 and suitable socket adapter.
Refer to Technical Data.

Caution: The relation between friction torque and preload force differs depending on the make of bearings.

Refer to pinion bearing table for specified friction torque.

Refer to Technical Data, and add 20 Ncm for the new shaft seal.





Install final drive, install side cover after marking with the appropriate washers (1) and install new O-rings (2). Tighten screws down evenly.
Tightening Torque, refer to Technical Data 33 11 2AZ.





Backlash/Tooth Contact Pattern Adjustment

Secure special tool 00 2 500 (dial gauge holder) and measure torsional face runout.
Refer to Technical Data.

Caution: The tooth contact pattern is always most important for a perfectly adjusted pinion/crown wheel.





To check the tooth contact pattern, coat the crown wheel teeth with printer's ink, turn in both directions several times and stop crown wheel suddenly with a piece of hard wood.





Correction to torsional face runout and contact pattern is performed by altering the thicknesses of both shims (1).

If backlash is too great, install a thinner shim on the crown wheel end.

If backlash is too small, use a thicker shim on the crown wheel end.

Axial displacement of the crown wheel of 0.01 mm signifies a change in tooth flank clearance of 0.0076 mm.

Caution: The total of both shim thicknesses must not be altered.

If a thicker or thinner shim to those fitted is required to adjust the contact pattern, the overall thickness must be re-established with a second shim. Failure to do this would alter the friction torque of the bearing.

Determining friction torque of differential bearings.
Refer to Replacing differential bearings, refer to 33 11 731.

Tooth contact pattern adjustment
Refer to 33 12 ... Basic rules for tooth contact pattern adjustment.





Extract old shaft seal with special tool 00 5 010 in conjunction with pressure piece.





Dip new shaft seals in final drive gear lube.

Drive in shaft seals with special tool 33 3 460 (impact bush) in conjunction with special tool 00 5 500 up to stop.

Replace drive flange if the bearing surface is seriously scored.





Installation:
Drive in new retaining plate with special tool 33 4 050 and special tool 00 5 500 (handle).