Backlash, Measuring and Adjusting

Backlash, Measuring and Adjusting

• Driveshaft installed with shims "S3" and " S4".

- Install differential with ring gear: S1 is on the cover side, S2 installed in transmission housing.

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

- Insert Locking Sleeve (VW 521/4) and (VW 521/12).

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

- Secure Dial Gauge Holder (VW 387) to housing.





- Insert dial gauge with Extension Pin (VW 382/10 ) (6 mm).

- Set Measuring Lever (VW 388) to dimension "a" = 73 mm (for ring gear dia. 182 mm).

- Determine play between the teeth flanks as follows:

- Turn ring gear until it makes contact with a tooth flank (end of backlash travel).

- Set dial gauge to "0" with 2 mm pre-load.

- Turn ring gear back until lying against an opposite tooth flank (backlash).

- Read off backlash and note measured value.

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

• If drive pinion turns when measuring, counter hold drive pinion so that an exact torsional backlash can be measured.

Determining average backlash

- Add the four measured values together and divide total by 4 to determine average.





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

• If measurements vary more than 0.06 mm from each other, ring gear or gear set is not installed correctly. Check installation, replace final drive set if necessary.

Determining thickness of adjustment shim "S 2"

Formula: "S2" = "S2* " - measured torsional backlash + specified torsional backlash





- Determine shim(s) according to table.

Available adjustment shims for "S2"





Determining thickness of adjustment shim "S 1"

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





- Determine shim(s) according to table.

Available adjustment shims for "S1"





Measurement check

- After installing adjustment shims "S1" and " S2", rotate differential 5 rotations in both directions so that tapered roller bearings settle.

- Measure backlash four times on circumference.





• Specification: 0.12 to 0.28 mm

• If backlash is outside tolerance, repeat adjustments. Do not change total shim thickness "Stotal" while doing so.

• The individual measurement values can deviate a maximum of 0.06 mm from each other