Crown Wheel Adjusting

Crown Wheel Adjusting

(Adjusting differential)

Special tools, testers and auxiliary items required

• Drift (VW 295)

• Dial gauge extension (VW 382/10)

• End measuring plate (VW 385/17)

• Universal dial gauge bracket (VW 387)

• Adjustable measuring lever (VW 388)

• Thrust plate (VW 402)

• Press tool (VW 408 A)

• Crown wheel adjusting tool (VW 521)

• Tube (30 - 14)

• Thrust piece (2050)

• Thrust plate (3005)

• Torque wrench (VAG 1331)

• Dial gauge

• Dial gauge extension, 30 mm

It is necessary to readjust crown wheel when the following components have been replaced:

Transmission housing, final drive cover, taper roller bearings for differential, differential cage or the final drive gear set

Table of adjustments, refer to => [ Adjustment Table ] Adjustment Table.

Determining total shim thickness "Stotal " for shims "S1" plus "S 2"

(adjustment of pre-load of taper roller bearings for differential)

• Pinion shaft removed

- Remove flange shaft oil seals

- Remove tapered roller bearing outer races for differential and remove shims, refer to => [ Differential ] Differential.

- Drive outer race for tapered roller bearing (right-side) with shim " S2" into transmission housing. For measurement purposes use a 1.30 mm thick "S2*" shim (or 2 shims of 0.65 mm).





• For measurement purposes a 1.30 mm thick shim "S2 " is inserted provisionally. This is referred to in the following as "S2*". "S2*" is exchanged with the final shim "S2" after determining backlash.

- Press tapered roller bearing outer race (left-side) without shim " S1" into cover for final drive.





- Install differential in transmission housing. The crown wheel is positioned on left-hand side (same side as cover for final drive).

- Install cover for final drive with 4 bolts (20 Nm).

- Turn transmission so that cover for final drive points upward.

- Turn differential 5 turns in both directions so that the tapered roller bearings settle.

- Place measuring plate (VW 385/17) on differential.

- Set up measuring tool using 30 mm extension.





- Set dial gauge (3 mm measuring range) - A - to " 0" with 2 mm preload.

• Tip of dial gauge must be located at center of differential.

- Raise differential without turning, read clearance off dial gauge and write down.

• Measurement in following example: 0.62 mm

• Secure special tools (VW 521/4) and ( VW 521/12) on right of differential (transmission side) to lift differential.





• If the measurement has to be repeated, the differential must again first be turned 5 turns in each direction to settle the tapered roller bearings.

Formula: "Stotal" = "S2* " + measured value + bearing preload





Determining thickness of shim "S1* "

• Provisional shim "S1*" is replaced with final shim "S1" after determining backlash.

• Total shim thickness "Stotal" remains unchanged.

Formula: "S1*" = "Stotal" - " S2*"





Refer to for required shims.

Measuring backlash

• Install pinion shaft with shims "S3" and " S4".

- Install differential with crown wheel: S1 is installed on cover side, S2 in transmission housing.

- Install cover for final drive and tighten bolts to 20 Nm.

- Insert crown wheel adjusting tool (VW 521/4 ) and (VW 521/12).

- Turn differential 5 turns in both directions so that the taper roller bearings seat properly.

- Secure universal dial gauge bracket (VW 387) to housing.





- Install dial gauge with dial gauge extension ( VW 382/10) (6 mm flat).

- Adjust measuring lever (VW 388) to distance "a" = 79 mm (for diameter 188 mm crown wheel).

- Measure play between teeth faces (backlash) as follows:

- Turn crown wheel until it makes contact with the face of one tooth (end of backlash travel).

- Preload dial gauge to 2 mm and set to "0".

- Turn back crown wheel until it makes contact with opposite tooth face (backlash).

- Take backlash reading and note down measured value.

- Turn crown wheel through 90° and repeat measurements a further 3 times.

Determining average backlash

- Add the four measured values together and divide by four.





• Result: the average backlash is 1.16 mm : 4 = 0.29 mm

• If the individual measurements differ from each other by more than 0.06 mm, the installation of the crown wheel 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* " - measured backlash + specified backlash





- Determine shim(s) according to table. For part numbers

Available shims for "S2"





* The exact shim thickness required can be obtained by using the shim tolerance variations. Install two shims if necessary.

Determining thickness of shim "S1"

Formula: "S1" = "Stotal" - " S2"





- Determine shim(s) according to table. For part numbers

Available shims for "S1"





* The exact shim thickness required can be obtained by using the shim tolerance variations. Install two shims if necessary.

Adjustment, Checking





- After installing shims "S1" and " S2", turn differential 5 turns in both directions so that the tapered roller bearings settle.

- Measure backlash four times on circumference.

• Specification: 0.12 to 0.28 mm

• Adjustment must be repeated if backlash is outside tolerance. The total shim thickness "Stotal" must remain unchanged.

• Deviation between individual measured values must not exceed 0.06 mm.