Carrier Bearings: Service and Repair

Remove final drive, refer to Differential, Service and Repair.





Secure final drive to special tool 33 1 010.
Drain oil and remove housing cover.

Installation:
Replace seal.
Tightening Torque, refer to Differential, Specifications.
Topping up with suitable oil, refer to Differential, Specifications.

Remove complete final drive housing, refer to Pinion Bearings, Service and Repair.





Pry off drive flanges with a tire iron for this purpose.





Mark bearing cap with punch marks and remove.

Caution:
In order to make friction torque adjustments easier, ensure that the bearing caps and spacer discs are not mixed up.





Remove complete differential case.

Caution:
Do not bend the pulse generator wheel.





Press pulse generator wheel off of differential case.

Caution:
Do not bend pulse generator wheel (3).





Installation:
Press fit pulse generator wheel using special tool 33 1 358.





Pull taper roller bearing off differential housing with special tool 33 1 300.





Remove crown wheel (cold).





Installation:
Cold-press new taper roller bearing on using special tool 33 1 020.

Caution:
Always only use same make bearings for both.





Lift shaft seals out of both bearing caps.





Press outer bearing race out with special tool 33 1 350 / 351.

Caution:
Special tool must engage in the bearing outer race.





Installation:
Press in new outer bearing races in with special tool 33 1 365.





If only the differential bearings are being replaced, the drive pinion can remain installed and the differential case is installed without the ring gear to determine thickness of shims.

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

Lubricate new bearings with approved final drive gear lube thoroughly and let them drip dry.





Install side bearing caps as marked with corresponding shims (1), but without O-rings (2) at first.
Uniformly tighten bearing cover screw on sides facing the crown wheel side.
Tightening Torque, refer to Differential Specifications.





The differential bores (1) always face up when the differential is installed correctly and this can be seen on the outside by way of tab (2).





The axial preload force of the differential housing bearing (4000 N) can be determined from the friction torque, refer to Differential Specifications.
Tighten bolts of second bearing cap uniformly only enough, that the differential can still be turned easily.





On the side tightened down to Tightening Torque, install an output flange and determine friction torque by means of a bracket with welded nut (in-house manufacture) and special tool 00 2 000.
Turn special tool at approx. 50/min.





The friction torque specified in the table for the final drive housing mount should be achieved, but do not exceed this value, refer to Differential Specifications.
If new shaft seals have already been installed, 20 Ncm must be added for each seal in which an output shaft runs while measuring.





If the specified friction torque is not achieved, although both bearing covers are tightened down to specified Tightening Torque, refer to Differential Specifications,
a thinner shim must be installed on the side facing the crown wheel and the measurement must be repeated.





If the friction torque is reached, although the second bearing cover has not yet been tightened to the specified torque, refer to Differential Specifications.
a thicker shim must be installed beside the crown wheel and the measurement must be repeated.





To make it easier to discover the shim thickness, the gap between shim and transmission case can be measured with a feeler gauge and then added to the thickness used for the shim.





Example:
Second bearing cover not tightened (screws evenly handtightened).
Friction torque, refer to Differential Specifications.

Gap Measured With Blade 0.20 mm
Used Shim 1.40
Install Shim Of Thickness 1.60

and measure again.





Remove differential.
Match side covers and shim of determined thickness, and do not mix them up.





Installation:
Clean tapped bores thoroughly (tapper).

Heat plate spring to max. 100 °C (thermo-chrome pin).
Mount crown wheel with two locally manufactured staybolts for guiding.





Install new bolts with Loctite No. 270.
Tighten bolts in order of 1 - 10).
Tightening Torque and torsion angle, refer to Differential Specifications.






Install differential with crown wheel and pulse gear.
Install side cover after marking with the appropriate washers (1) and new O-rings (2).
Tightening Torque, refer to Differential Specifications.





Backlash/tooth contact pattern adjustments

Secure special tool 00 2 500 (dial gauge holder) and measure torsional face runout, refer to Differential Specifications.

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

Basic rules for contact pattern adjustment, refer to Differential, Adjustment.





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.





A correction to torsional face runout, refer to Differential Specifications,
and contact pattern is performed by changing the thickness 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 thickness of both shims may no longer be changed.

If a thinner or thicker shim is required to correct the tooth contact pattern, the total thickness must be corrected with the second shim, since otherwise the friction torque of bearings would be changed again.





Installation:
Dip shaft seal in final drive oil.

Drive shaft seal firmly home with special tool 33 1 230 in conjunction with special tool 00 5 500.
Replace drive flange if the bearing surface is seriously scored.

Note:
The special tool 33 1 230 may have to be remachined on account of the casting tolerances.





Installation:
Place round wire snap ring (1) in the groove of the differential case in such a manner that both ends of the round wire snap ring are recessed in the groove, before installing the drive flange.

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.