Ring Gear Adjusting

ADJUSTING DIFFERENTIAL

Ring gear must be adjusted if any of the following have been replaced:
- Transmission housing
- Final drive cover
- Differential tapered roller bearings
- Differential housing
- Final drive gear set (ring and pinion)
Refer to "Ring and Pinion Gear Set, List Of Adjustments".

Determining Total Shim Thickness Stotal (S1 Plus S2)
(Adjusting preload of differential tapered roller bearings)
- Pinion removed
- Remove oil seals and outer races of differential bearings and remove shims: refer to "Differential, Removing and Installing".
- Drive in tapered roller-bearing outer races without shims as far as possible: refer to "Differential, Removing and Installing".
- Install differential in housing without speedometer drive gear.

Ring gear is on left-hand side (in front of final drive cover).

- Install cover and tighten bolts to 25 Nm (18 ft lb).
- Mount special tool 521/4 and sleeve 521/8 on differential housing (transmission housing side) as shown in illustration below.
- Use sleeve 521/7 for smaller differential housing.






- Set up measuring tools.
- A = Dial indicator extension approx. 30 mm long
- Set dial indicator (3 mm range) to zero with 1 mm preload.






- Move differential up and down; take and record dial indicator reading.

Example: 1.42 mm

CAUTION! Do not turn the differential while making the measurement, or the bearings will settle and cause a false reading.

Determining Stotal (S1 + S2)
Stotal = dial indicator reading + preload






Example
- Install shim of required thickness (1.92 mm in example) behind bearing outer race in transmission housing (S2 side). Select shims from table: refer to "Determining Thickness of Shim S2" shown below.






- Measure bearing preload using commercially-available torque gauge -A- (0-600 Ncm).
- Lubricate bearings with transmission oil.

Note: For smaller differential housing, use sleeve 527/7 instead of sleeve 527/4.






Note: When gear set is being adjusted, pinion should now be adjusted and setting checked: refer to "Pinion Adjusting".

Adjusting Backlash
Pinion installed with shims S3 and S4
- Install differential Stotal (S1 + S2) in transmission housing.
- Rotate differential several times in both directions so that tapered roller bearings can settle.






- Set up measuring tools
Use extension VW 382/10 16 mm square end)
Use sleeve 521/7 for smaller differential housing
- Set lever VW 388 to dimension -a-.
Ring gear dia. 170 mm: dimension -a- = 67 mm
Ring gear dia. 180 mm: dimension -a- = 72 mm
- Turn ring gear to stop, set dial indicator to zero.
- Turn ring gear back and read backlash. Record the reading.






- If pinion has too little preload, clamping plates 3177 (-A-) must be installed so backlash can be measured exactly.

Differential must then be installed so that cut-out for installing bevel gears faces pinion.

- Repeat procedure three more times, turning ring gear 1/4-turn (90°) each time.
- Add four readings together and calculate average backlash.
- With clamping bracket 3177 installed, turn differential 180°, reinstall and repeat measuring procedure.

CAUTION! If the individual readings differ from one another by more than 0.06 mm, there is something wrong with the installation of the ring gear, or with the gear set itself. Check all assembly operations and, if necessary, replace the gear set.

Determining Average Backlash






Example
- Average backlash 3.36/4 = 0.84 mm

Determining Thickness Of Shim S2
(End opposite ring gear)
S2 = Stotal - average backlash + lift (constant value)
Lift = 0.15 mm






Example
The tolerances in nominal shim sizes make it possible to choose a shim with the precise thickness required for S2.






Available shims S2 (in transmission housing)

Determining Thickness Of Shim S1
(Ring gear side)
S1 = Stotal - S2






Example
The tolerances in nominal shim sizes make it possible to choose a shim with the precise thickness required for S1.






Available shims S1 (in transmission housing cover)
- Install shims on ring gear side (S1), opposite side (S2).
Use two shims to achieve required thickness if necessary.

Checking Measurements
- Measure backlash four times around ring gear circumference.
* Backlash must be 0.12-0.22 mm.

CAUTION: The individual readings must not differ from one another by more than 0.05 mm.