Ring Gear, Adjusting
Adjusting differential
For a list of the repairs which will require the ring gear to be adjusted, Refer to List of Adjustments.
Special tools and equipment
- VW382/10 extension pin
- VW385/17 magnetic plate
- VW386A clamping piece
- VW387 dial indicator holder
- VW388 measuring lever
- VW402 thrust plate
- VW408A punch
- VW472/1 pressure piece
- VW521 adjustment tool
- Torque gauge 0-600 Nm (53 inch lbs.)
- Dial indicator
- Dial indicator extension
Determining total shim thickness "Stotal" (S1 + S2)
Adjusting preload of tapered roller bearings for differential
- Pinion shaft removed
Note: If only the tapered roller bearings for the differential are being replaced, the ring gear can be removed from the differential housing. The pinion shaft does not have to be removed.
- Remove seals and outer races of both tapered roller bearings for differential.
- Remove shims, Refer to Front Final drive differential, disassembling and assembling.
- Press right tapered roller bearing outer race with shim S2 into transmission housing, See Fig. 2, Refer to Front Final drive differential, disassembling and assembling. Shim S2* with thickness of 1.20 mm (two 0.60 mm shims) is used for initial measurement.
Note: For measurement purposes, a shim S2 of 1.20 mm is initially inserted and referred to as S2* in the text. After determining backlash, S2* will be replaced by the correct shim S2.
- Press tapered roller bearing outer race into differential cover without shim S 1, See Fig. 8, Refer to Front Final drive differential, disassembling and assembling.
- Insert differential without speedometer gear drive into transmission housing. Ring gear is positioned on left-hand side in front of final drive cover.
- Install differential cover with 4 bolts and tighten to 25 Nm (18 ft. lbs.).
- Position transmission so differential cover faces upward.
- Turn differential 5 turns in both directions so tapered roller bearings settle.
- Assemble measuring equipment, using 30 mm dial indicator extension.
- Set dial indicator (3 mm measuring range) -A- to "O" with 2 mm preload.
Note: The tip of the dial indicator must be positioned on the center of the differential.
- Lift differential without turning, and read off play on dial indicator.
- Measurements in the example: 0.62 mm
Notes:
- To lift differential, attach VW52114 locking sleeve and VW521112 on the right of the differential (housing side).
- If the measurement has to be repeated, the pinion shaft with hollow shaft must be fumed 5 turns in each direction first to settle the tapered roller bearing.
Formula:
- Stotal = S2*- + Measurement + Bearing Preload
Example:
Inserted Shim(s) S2* 1.20 mm
+ Measured Value 0.062 mm
+ Bearing Preload (Constant Value) 0.030 mm
= Total Thickness Stotal for S1 + S2 2.12 mm
Determining thickness of shim "S1*"
Notes:
- The preliminary adjustment shim S1* will be replaced with the final shim S1 after determining the backlash.
- The total shim thickness Stotal remains unchanged.
Formula:
S1* = Stotal - S2*
Example:
Total Thickness Stotal for S1 + S2 2.12 mm
- Inserted Shim(s) S2* 1.20 mm
= Thickness of Shim S1* 0.92
Measuring friction torque
Notes:
- Differential tapered roller bearings are low friction bearings. Therefore the friction torque only has a limited use as a check. Correct adjustment is only possible by determining the total shim thickness Stotal.
- Do not additionally oil new tapered roller bearings for friction torque measurement. The bearings have already been treated with a special oil by the manufacturer.
- Pinion shaft removed
- Install torque gauge 0-600 Nm (53 inch lbs.) -A- onto differential.
B - Socket
- Read friction torque.
Friction torque specifications:
New Bearings Used Bearings
150 - 350 Ncm (13 - 31 in. lb.) 30 - 60 Ncm (3 - 5 in. lb.)
Note: For a readjustment of the final drive gear set (pinion shaft and ring gear), the pinion shaft adjustment should now be checked, Refer to Pinion shaft, adjusting.
Measuring backlash
Position of ring gear in transmission housing
- Pinion shaft with shims S3* and S4* installed
- Install differential.
- Turn differential 5 turns in each direction to settle tapered roller bearings.
- Secure VW387 dial indicator holder onto housing.
- Attach VW521/4 locking sleeve and VW521/12.
- Install dial indicator and VW382/10 extension pin (6 mm flat).
- Adjust VW388 measuring lever to dimension -a-:
Distance -a-: 67 mm (2.637 inch) for 170 mm (6.693 inch) diameter ring gear.
- Determine play between teeth flanks as follows:
- Turn ring gear until it makes contact with tooth flank (end of backlash travel).
- Set dial indicator to "O" with 2 mm preload.
- Turn ring gear back against opposite tooth flank (backlash).
- Recording (backlash) indicated on gauge.
- Turn ring gear 90 further each time and repeat measurement 3 times.
Notes:
- Install VW386A clamping piece if the pinion shaft rotates when the differential is fumed. This way the exact backlash can be measured.
- Loosen clamping piece in order to turn the ring gear further.
Determining average backlash
- Add four measured values together and divide by four.
Example:
1st Measurement 0.28 mm
+ 2nd Measurement 0.30 mm
+ 3rd Measurement 0.30 mm
+ 4th Measurement 0.28 mm
= Sum of Measured Values 1.16 mm
Result: The average backlash is 1.16 mm / 4 = 0.29 mm
CAUTION: If the individual measurements differ by more than 0.06 mm from each other, the installation of the ring gear or the final drive gear set itself is not correct Check installation, replace final drive gear set if necessary.
Determining thickness of shim S2
Formula:
S2 = S2* - Backlash + Lift
Example:
Inserted Shim S2* 1.20 mm
- Average Backlash 0.29 mm
+ Lift (Constant Value) 0.15 mm
= Thickness of Shim S2 1.06 mm
The shims are available for S2
Shim Thickness (mm) (1)
0.45 0.65 0.85
0.50 0.70 0.90
0.55 0.75
0.60 0.80
(1): By using shim tolerances it is possible to find exact shim thickness required, insert two shims if necessary.
Determining thickness of shim "S1"
Formula:
S1 = Stotal - S2
Example:
Total Shim Thickness Stotal for S1 + S2 2.12 mm
- Thickness of Shim S2 1.06 mm
= Thickness of Shim S1 1.06 mm
The shims are available for S1
Shim Thickness (mm) (1)
0.45 0.65 0.85
0.50 0.70 0.90
0.55 0.75
0.60 0.80
(1): By using shim tolerances it is possible to find exact shim thickness required, insert two shims if necessary.
Checking measurement
- After installing shims S1 and S2, turn differential 5 turns in both directions so that tapered roller bearings settle.
- Measure backlash four times on circumference.
Specifications: 0.12 - 0.22 mm
Notes:
- If the backlash lies outside the tolerances, the adjustments must be repeated. The total shim thickness Stotal must remain the same.
- The individual measurements must not differ by more than 0.06 mm from each other.