Adjusting Backlash

Adjusting backlash
(position of ring gear in transmission housing)
^ Drive pinion installed with shim S3
^ Differential installed with shims "S1 *" and "S2*"
^ Insert differential in final drive housing, install cover and tighten all bolts to 25 Nm.
^ Turn differential 5 rotations in each direction to seat the tapered roller bearing.





^ Install measuring tools.
^ Use VW382/10 extension pin, 6 mm.
^ Set VW388 measuring lever to dimension "a" = 60 mm.
^ Determine backlash between teeth flanks as follows:
^ Turn ring gear until it contacts a tooth flank (end of backlash travel).
^ Set dial indicator to 0 with 1 mm preload.
^ Turn ring gear back until it contacts opposite tooth flank (backlash).
^ Read backlash and note.
^ Turn ring gear 90° every time and repeat measurement 3 times.

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

Determining average backlash
Example:
1. Measurement 0.28 mm
+ 2. Measurement 0.30 mm
+ 3. Measurement 0.30 mm
+ 4. Measurement 0.28 mm
Total of measurements 1.16 mm
Result: The average backlash is 1.16 mm / 4 = 0.29 mm

Determining thickness of shim "S2"
Formula:
"S2" = "S2*" minus backlash - lift
Example:
Installed shim "S2*" 1.00 mm
^ Average backlash 0.29 mm
Lift (constant) 0.15 mm
Thickness of shim "S2" 0.86 mm
^ Determine shim as closely as possible according to table.





Available shims for S2

Determining thickness of shim "S1"
Formula:
"S1" = "Stotal" minus "S2"
Example:
Total shim thickness "Stotal" for 1.80 mm "S1 + S2"
Thickness of shim "S2" 0.86 mm
Thickness of shim "S1" 0.94 mm
^ Determine shim as closely as possible according to table.





Available shims for S1

Checking measurement





^ Drive pinion installed with shim S3
^ Differential installed with shims "S1" and "S2"
^ Turn differential 5 rotations in each direction to seat the tapered roller bearing.
^ Measure backlash 4 times on circumference.
^ Specification: 0.12 to 0.22 mm

Note:
^ 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