Adjusting ring gear

Determining total shim thickness "Stot." (Si + S2)

The ring gear must be readjusted if the transmission case, transmission side cover, taper roller bearing for differential, differential housing or drive set have been replaced.


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

1. Remove adjusting shim "Si" (in transmission side cover).

2. Adjusting shim "S2" remains in the transmission case.

3. Make sure that the bearing outer races of the tapered roller bearings are well seated in the transmission case or in the transmission side cover.

4. Insert differential into transmission case and rotate several times.

5. Fit transmission side cover without seals and tighten all hexagon head bolts to 23 Nm (17 ftlb).

6. Place gauge block plate 9281 on the collar of the differential.

7. 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 mm long) B - Gauge block plate 9281

8. Using a suitable tool, move differential up an down.

Read off backlash on the dial gauge and note.


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

9. Remove adjusting shim "S2" and determine thickness using a micrometer.

10. Calculate "Stot".

"Stot." = Thickness of adjusting shim "S2" + measured value

+ pressure fit of taper roller bearings Example

Thickness of adj. shim "S2" 1.70 mm Measured value 0.91 mm

Press fit (constant value) 0.24 mm "Stot" 2.85 mm

11. Spread calculated shim thickness "Stot" as follows.

To start with the backlash adjustment, the thickness of adjusting shim "Si" is reduced by 0.40 mm while the thickness of adjusting shim "S2" is increased by 0.40 mm.


Total shim thickness of adjusting shims

Thickness of adjusting shim "Si"


The adjusting shims are avail, in thickneses of 1.0...2.0 mm in increments of 0.05 mm.

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


Calculated shim thickness

Rounded down shim thickness

1.025 mm

Thickness of adjusting shim "S2

2.85 mm

1.825 mm

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