Adjusting circumferential backlash


The backlash to be set is engraved on the ring gear.

1. Fit drive pinion using shims „S3" and "S4".

2. Fit differential with tapered roller bearings into housing, inserting the spacers (Si + S2) determined before.

3. Fit transmission side cover and tighten all mounting bolts to 25 Nm.


Always make sure that there is a certain amount of backlash when tightening the bolts.

Never allow the drive pinion to bind.

4. Assemble measuring lever VW 388 and adjusting device VW 521/4 and adjust lever length to 80 mm with the plunger. Refer to dimension "a" in the figure.

5. Insert adjusting device with clamping sleeve (Special Tool 9145) into the differential and clamp firmly.

6. Rotate differential in both directions several times to allow the tapered roller bearings to settle.

7. Fit universal dial gauge holder with flat extension in such a way as to produce a right angle between dial gauge axis and lever.


Dimension "a" = approx. 80 mm

8. Turn ring gear carefully at the clamping screw of the adjusting device up to the stop and set the dial gauge to zero. Turn back ring gear and read off circumferential backlash. Note the reading.

9. After turning the ring gear another 90° each, repeat measuring procedures three times. The measured values must not deviate from one another by more than 0.05 mm.


The backlash to be adjusted is engraved on the ring gear. The actual value may be less than the specified value by - 0.05 mm. Under no circumstances must the backlash be greater than the specified value.

10. If the required backlash cannot be obtained, replace spacers (Si + S2) again. The total shim thickness (S tot) must not be altered, however.


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