Adjusting ring gear

Determine total shim thickness "S tot." (Si + S2).

The ring gear must be adjusted, if the:

transmission case, lateral transmission cover, tapered roller bearing for differential, differential housing or drive set have been replaced.


The drive pinion must be removed to determine the preload of the differential tapered roller bearings.

1. Make sure that the bearing outer races of the tapered roller bearings are well seated in the transmission case or lateral transmission cover, respectively.

2. Fit one spacer ring (2.5 mm thick) on the ring gear side and on the opposite side of the differential to be used.

3. Insert differential into transmission case and

4. Fit lateral transmission cover without seal and tighten all hexagon-head nuts to 23 Nm (17 ftlb.).

5. Put gauge block plate VW 385/17 on the collar of the differential.

6. Fasten universal dial gauge holder VW 387 with dial gauge and extension to the case and set to 0 with 2 mm preload.


A = Dial gauge extension (approx. 30 to 40 mm long)

B = Gauge block plate VW 385/17

7. Move differential up and down. Read off backlash on the dial gaug and note.


Do not turn differential while measuring backlash as this will give an incorrect reading.

"S tot." = Fitted shim thickness + Measured value

+ Pressure fit of tapered roller bearing


Thickness of shims inserted Measured value Pressing (constant value)

9. Remove differential, pull off both tapered roller bearings and split calculated shim thickness "S tot." as follows. Selcect spacer Si 0.70 mm thinner and S2 0.70 mm thicker as a starting point for subsequent adjustment of the backlash.


Total shim thickness of spacers

The calculated shim thicknesses must be rounded up or down for plausible dimensions that will not alter the total thickness S1 and S2.


Calculated thicknesses

Rounded thicknesses

Measure shims with a micrometer in several places. Permissible deviation 0.02 mm. Also check shims for burrs and damage.

Thickness of spacer Si

Thickness of spacer S2


Spacers are available in thicknesses of 1.6 to 3.1 mm in increments of 0.10 mm.

By using a 0.25 mm shim, the shim thicknesses may be graduated in increments of 0.05 mm.

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