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
Refer to "List of Adjustments".

Determining Total Shim Thickness Stotal (S1 + S2)
(Adjusting preload of differential tapered roller bearings)

Pinion removed
- Remove oil seal and tapered roller bearing outer races for differential, and remove shims: refer to "Overview" at Disassembling and Assembling.
- Drive tapered roller bearing outer races fully in without shims: refer to "Overview" at Disassembling and Assembling.
- Insert differential into housing without speedometer gear.

The ring gear is positioned on the left-hand side (in front of the final drive cover).

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






- Install 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 reading from dial indicator.

Example: 1.42 mm

CAUTION! Do not turn the differential when carrying out the measurement, as the bearings will settle and produce a false reading.






Calculating Stotal (S1 + S2)
- Install shim of calculated total thickness, 1.92 mm in example, behind tapered roller bearing outer race in transmission housing (S2 side).
- Select shims from table (shown below)







- Measure friction torque.
- A = Commercial torque gauge, 0-600 Ncm (0-53 in lb)
- Lubricate bearing with gear oil.






These friction torques should be set

Note: When the gear set is being adjusted, perform the pinion adjustment and check setting: refer to "Pinion, Adjusting".

Adjusting Backlash
- Pinion installed with shims S3 and S4.

Differential:
- Install Stotal (S1 plus S2) in transmission housing.
- Rotate differential several times in both directions so that tapered roller bearings can settle.






- Install measuring tools.
- Use dial indicator extension VW 382 (6 mm plane).
- Set measuring lever VW 388 to dimension -a- for ring gear For ring gear diameter or 170 mm, dimension -a- = 67 mm






- Install clamping device and clamp pinion.
- Turn ring gear as far as stop, set dial indicator to zero.
- Turn ring gear back and take reading of backlash. Record the reading.
- Loosen clamping device.
- Repeat procedure three more times, turning ring gear 90° each time.
- Add together four readings and calculate average backlash.

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

Determining Thickness Of Shim S2
(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).

Note: If the required shim thicknesses are greater than the largest shim listed in the table, two shims that combine to produce the required thickness may be installed.

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

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