Carrier Bearings: Service and Repair
Replacing Both Bearings In Final Drive Case (Type K)
Final Drive Removed
Remove final drive.
Secure final drive to special tool 33 1 010.
Drain off fluid.
Take off case cover.
Installation:
Replace seal. Top up oil.
Press off drive flange with pry bar.
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 the pulse generator wheel.
Installation:
Press fit pulse alternator wheel using special tool 331 304.
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 331 330.
Caution: Always only use same make bearings for both.
Lift shaft seals out of both bearing caps.
Press off outer bearing race with special tool 33 1 350 and special tool 33 1 351.
Caution: Special tool 33 1 351 must engage in outer bearing race.
Installation:
Press new outer bearing race in with special tool 33 1 373.
If only the differential bearings are being replaced, the drive pinion can remain installed and the differential case is installed without the ring gear for determination of shim thickness.
Caution: Note make of bearings - this is required to determine the friction torque.
Oil the new bearings well with differential oil and allow to drip-drain.
Install side bearing caps marked with belonging shims (1), but at first without O-rings (2).
Tighten down bearing cover screws on bevel gear end evenly.
The lubricant bores (1) always face up when the transmission 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.
Tighten bolts of second bearing cap uniformly only enough, that the differential can still be turned easily.
On the side tightened down to proper 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 friction torque meter at speed of approximately 50 rpm.
The friction torque level indicated in the final drive bearing table should be achieved, but should not be exceeded, refer to Technical Data.
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.
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.
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 cap not tightened (bolts screwed in uniformly).
Gap measured with blade 0.20 mm
Used shim 1.40 mm ______________
Install shim of thickness 1.60 mm
Install 1.60 mm thickness of shim and repeat measurement.
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 maximum 100°C (thermo-chrome pin).
Mount crown wheel with two locally manufactured staybolts for guiding.
Installation:
Install new bolts with Loctite No. 270.
Tighten bolts in order of 1 - 8.
Note Tightening Torque and torsion angle.
Installation:
Install differential with ring gear and pulse gear.
Install side cover after marking with the appropriate washers (1) and new O-ring (2).
Adjusting torsional face runout/contact pattern:
Secure special tool 00 2 500 (dial gauge holder) and measure torsional face runout.
Caution: The contact pattern is always the key to perfect adjustment of a gear train, refer to Basic Rules of Contact Pattern 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.
Correction of 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 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 3 460 in conjunction with special tool 00 5 500.
Replace drive flange if the bearing surface is seriously scored.
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 round wire snap rings.