Ring Gear, Adjusting

RING GEAR, ADJUSTING
(Adjusting differential)
For repairs which require adjustment of the ring gear, refer to Adjustment Overview. Adjustment Overview

NOTES:
^ The tapered roller bearings for the differential gear are low friction. Therefore, the turning torque can only be used conditionally as an inspection value, Correct adjustment is only possible by determining the total shim thickness "S total. "
^ Do not additionally treat new tapered roller bearings to measure turning torque. For this purpose, the bearings are already pre-treated with a special oil.

Determining Total Shim Thickness "S Total" (S1 + S2)
(Setting preload of tapered roller bearing for differential)
- Drive pinion removed or ring gear disassembled from differential housing

Note: When the tapered roller bearings for the differential are to be replaced, the crown wheel can be removed from the differential housing. The drive pinion need not be removed.

- Remove sealing ring using lever.
- Drive out outer race of tapered roller bearings and remove shims.
- Drive outer race of tapered roller bearing for left differential gear (housing side) with shim "S2" into housing.
To perform the measurement, use a shim "S2" with a thickness of 1.00 mm (one 0.80 mm and one 0.20 mm shim).

Note: For measurement purposes a shim "S2" of 1.0 mm is initially inserted and will be designated "S2" in the following. After determining backlash, "S2*" will be replaced with the correct "S2".

- Drive in outer race of right tapered roller bearing for differential (final drive cover side) to stop without shims.
- Install differential gear in housing,
The ring gear is positioned on the right (cover) side.
- Install cover and tighten bolts.
Tightening torque: 25 Nm (18 ft. lbs.)





- Install special tools VW 521/4 and 521/8 in differential gear housing on housing side.
- Turn cover of housing upward.

Note: Turn differential gear 5 turns in both directions so that tapered roller bearings settle,





- Install measuring tools.
A - Dial indicator extension, approx. 30 mm long
B - Bolt M8x45
- Place dial indicator extension in center of VW385/17 measuring plate.
- Set dial indicator (3 mm measuring range) to "0" with 2 mm preload.





- Lift differential, read play on dial indicator and record.
Measurement in following example: 0.50 mm

Note: If the measurement has to be repeated, the differential must again be turned 5 turns in each direction to settle the tapered roller bearing.

Calculating "S total"
S total = S2* + measurement + pre-load
The specified bearing preload is obtained by adding a constant preload figure of (0.30 mm) to the reading obtained (0.50 mm) and the thickness of the shim installed (1.00 mm).





Example:

Determine Shim Thickness "S1*"

Notes:
- The preliminary adjustment shim "S1*" will be replaced with the final shim "S1" after determining the backlash.
- The total shim thickness "S total" remains unchanged.
S1 = S total - S2





Example:
- Determine shim(s) from table.

Measuring Turning Torque (Check)
- Drive pinion removed
- Differential installed with shims "S1*" and "S2*"





- Install torque gauge 0 - 600 Ncm (-A-) on differential.
- Measure turning torque.





Turning torque specifications

NOTES:
- The tapered roller bearings for the differential gear are low friction. Therefore, the turning torque can only be used conditionally as an inspection value. Correct adjustment is only possible by determining the total shim thickness "S total".
- Do not additionally treat new tapered roller bearings to measure turning torque. For this purpose, the bearings are already pre-treated with a special oil.
- If the ring gear and pinion set is being adjusted, a pinion adjustment (with checks) should be carried out.