Ring Gear, Adjusting
Ring gear, adjusting(Adjusting differential)
Special tools and workshop equipment required
- VW385/17 End measuring plate
- VW 387 Universal dial gauge bracket
- VW 388 Adjustable measuring lever
- VW 521/8 Adjusting device
- 3177 Retainer
- VAG1331 Torque wrench
- VW 382/10 Dial test indicator extension
- VW 402 Press plate
- VW408A Press tool
- VW 459/2 Installing and removing tool
- VW 472/1 Thrust piece
- VW 681 Oil seal extractor
It is necessary to readjust the ring gear when:
Transmission housing, final drive cover, differential taper roller bearings, differential housing or the ring gear and pinion are replaced.
Adjustment overview
Determining total shim thickness "S_total" (S1 plus S2).
(Adjusting differential taper roller bearings)
- Pinion shaft removed!
- Pull out flanged shaft oil seal with oil seal extractor VW 681.
- Remove differential taper roller bearing outer race and take out shims.
- Press outer race for taper roller bearing with shim S2 into transmission housing.
- For measurement, a shim S2* with thickness 1.20mm (2 shims of 0.60mm) is used.
As a prerequisite for the measurement, a temporary S2 shim of 1.20 mm is inserted. It is designated S2* below. After the determination of backlash, S2* is replaced with the final S2 shim.
- Press outer race of taper roller bearing without shim S1 into final drive cover.
Note: Use thrust piece 2050 instead of thrust piece VW47211 for transmissions with enlarged taper roller bearing.
- Install differential in housing without speedometer drive wheel.
The ring gear is located on the left-hand side (cover side).
- Fit cover and tighten bolts to 25 Nm.
- Turn transmission so that final drive cover faces upwards.
- Turn differential 8 turns in both directions, so that the taper roller bearings settle.
- Place measuring plate VW 385/17 on differential.
- Fit measuring tools.
- Place D.T.I. extension on the center of the measuring plate VW 385/17.
- Set dial gauge (3 mm range) to zero with 2 mm preload.
D.T.I. extension 30 mm
- Move differential up and down (direction of arrow) with special tool VW 521.
- Read off play from D.T.I.
Example: 0.62 mm
"S_total" = S2* + dial gauge reading + preload
Determining shim "S1" thickness
Notes:
- The temporary shim S1* is replaced with the final shim S1 after backlash is determined.
- The total shim thickness "S_total" remains unchanged.
S1* = S_total - S2*
Example:
Note: Allocate shims according to parts catalog.
Measuring backlash
Pinion shaft installed with S3 and S4
- Install differential with ring gear: S1* is installed on cover side and S2* in transmission housing.
- Fit final drive cover and tighten bolts to 25 Nm.
- Turn differential 5 rotations in each direction so that the taper roller bearings settle.
- Fit measuring tools.
- Use D.T.I. extension VW 382/10 (6 mm flat).
Adjust measuring lever VW 388 to dimension "a" according to ring gear
Ring gear Dimension "a"
180mm 72 mm
170mm 67 mm
- Turn ring gear to stop. Set D.T.I. to zero with 2mm preload, turn ring gear back and read off backlash. Note reading.
Note: If differential turns also during measurement, fit retainer 3177 -A- so that backlash can be measured precisely.
- Loosen ring gear adjusting device VW521 to turn ring gear further.
- The differential must then be installed so that both cut-outs for the planet pinions face towards pinion shaft.
- Repeat measurement three times, turning ring gear through 90° each time. Add the four results and calculate the average backlash.
- If retainer 3177 is being used, install differential turned through 180° and repeat measurement.
Calculating average backlash
Example:
1st measurement 0.28 mm
+ 2nd measurement 0.30 mm
+ 3rd measurement 0.30 mm
4th measurement 0.28 mm
Total 1.16 mm
Average backlash = 1.16 mm: 4 = 0.29 mm.
If the individual measurements differ by more than 0.06 mm this means that the installation of the ring gear is not correct or that the ring gear and pinion themselves are defective. Recheck the installation, and if necessary replace ring gear and pinion.
Determining shim S2 thickness
(opposite ring gear)
S2* = Inserted shim(s)
-average backlash
+Lift (constant value)
Lift = 0.1 5 mm
Example:
Note: Allocate shims according to parts catalog.
Available shims for S2
- Different tolerances make it possible to select the exact thickness of shim(s) required.
Determining shim S1 thickness
(ring gear side)
S1 = S_total - S2
Example:
Note: Allocate shims according to parts catalog.
Shims available for S1
- Different tolerances make it possible to select the exact thickness of shim(s) required.
Determine and install shims S1 on ring gear side, and S2 opposite the ring gear, fitting 2 shims if necessary.
Carrying out check measurement
Measuring backlash
- It must be 0.12 to 0.22 mm.