Adjusting Ring Gear

Determine Total Shim Thickness "S Tot." (S1+S2)

NOTE:
- The ring gear must be adjusted, if the:
- transmission case
- lateral transmission cover
- tapered roller bearing for differential
- differential housing
- 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 rotate several times.
4. Fit lateral transmission cover without seal and tighten all hexagon head nuts to 23 Nm (17 ft lb).
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.
7. Move differential up and down.
- Read off backlash on the dial gauge and note.

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

8. Calculate "S tot.".
- "S tot." Equals fitted shim thickness Plus measured value Plus pressure fit of tapered roller bearing

Example:
Thickness of shims inserted 5.00 mm
Measured value 0.75 mm
Pressing (constant value) 0.40 mm _________
"S tot." 6.15 mm

9. Remove differential, pull off both tapered roller bearings and split calculated shim thickness "S tot." as follows.
- Select spacer "S1" 0.70 mm thinner and "S2" 0.70 mm thicker as a starting point for subsequent adjustment of the backlash.

Example:
Total shim thickness of spacers: "S1" + "S2" = 6.15 mm
Thickness of spacer "S1"
6.15 mm Divided by 2 Equals 3.075 mm, Minus 0.700 mm Equals 2.375 mm
Thickness of spacer "S2"
6.15 mm Divided by 2 Equals 3.075 mm, Plus 0.700 mm Equals 3.775 mm


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

Example:
Calculated thicknesses
"S1" + "S2" = 2.375 + 3.775 = 6.15 mm
Rounded thicknesses
"S1" + "S2" = 2.35 + 3.80 = 6.15 mm

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