Perform Check Measurement

Perform check measurement
Checking dimension "r"
^ Rotate drive pinion at least 5 complete revolutions in both directions.





^ Install universal mandrel and perform check measurement.
If shims have been determined correctly, dial indicator must indicate deviation r with a tolerance of � 0.04 mm (reading counterclockwise in red number display).
^ Secure drive pinion nut using mandrel.

Note: Measure radial run-out at drive shaft flange and mark.

Ring gear, adjusting
(Adjusting differential)
Procedures to be performed after ring gear is adjusted, Adjustment overview on.

Note:
^ Tapered roller bearings for differential are low-friction bearings. Therefore friction torque can only be used for check measurement in a limited way. A correct adjustment is only possible by determining the total thickness "Stotal".
^ Do not grease new tapered roller bearings additionally for friction torque measurement. The bearings are already greased with a special oil from the factory.
^ Total shim thickness Stotal for shims S1 + S2, determining (adjust preload of tapered roller bearing for differential)
^ Drive pinion removed or ring gear detached from differential housing

^ Pry out drive flange seal using tire iron.
^ Remove tapered roller bearing outer races for differential and remove adjustment shims.
^ Press left tapered roller bearing outer race for differential (housing side) with adjustment shim "S2" into differential housing page 39-113. Use a shim "S2*" with a 1.00 mm thickness for measurement purposes (1 shim with 0.80 and 1 shim with 0.20 mm).

Note: All measurements are performed with shim S2 of 1.00 mm thickness. The shim will be indicated by "S2*" in the following procedures. After determining backlash, S2* is replaced by final shim S2.

^ Drive in right tapered roller bearing outer race for differential (cover side) without adjustment shims up to stop.
^ Insert differential in housing. Ring gear is on the right side (cover side).
^ Install cover and tighten bolts to 25 Nm.





^ Install VW521/4 locking sleeve and 521/8 sleeve press tool onto housing side of differential housing.
^ Rotate cover side of differential housing upward.
^ Turn differential 5 rotations in each direction to seat the tapered roller bearing.
^ Place VW385/17 magnetic plate onto differential.





^ Install measuring tools
A- Dial gauge extension approximately 30 mm long
B - Hex bolt M8 x 45
^ Set dial gauge extension onto center of VW385/17 magnetic plate.
^ Set dial indicator (3 mm measuring range) to 0 with 2 mm preload.
^ Lift differential without turning it, read backlash on dial indicator and note. Measured value in the following example: 0.50 mm





Note: If measurement is repeated, differential must first be rotated 5 complete revolutions in both directions again to seat tapered roller bearing.

Formula: "Stotal" = "S2*" + measured value bearing preload
Example:
Installed shim(s) "S2*" 1.00 mm
+ Measurement 0.50 mm
+ Bearing preload (constant) 0.30 mm
= Total shim thickness "Stotal" for shims "S1 + S2" 1.80 mm

Determining thickness of shim "S1*"

Note:
^ "S1*" is used for the initial measurement. After determining backlash, "S1 *" is replaced with final shim "S1".
^ The total shim thickness "Stotal" remains unchanged.

Formula:
"S1*" = "Stotal" minus "S2"
Example:
Total shim thickness "Stotal" for shims "S1 + S2" 1.80 mm
^ Installed shim(s) "S2*" 1.00 mm = Thickness of shim "S1*" 0.80 mm
^ Calculate adjustment shims as accurately as possible according to the table.

Measuring friction torque (check measurement)
^ Drive pinion removed
^ Differential installed with shims "S1*" and "S2*"





^ Torque gauge O to 600 Ncm -A- installed on differential.
^ Read friction torque.





Friction torque specified values:

Note:
^ Tapered roller bearings for differential are low-friction bearings. Therefore friction torque can only be used for check measurement in a limited way. A correct adjustment is only possible by determining the total thickness "Stotal".
^ Do not grease new tapered roller bearings additionally for friction torque measurement. The bearings are already greased with a special oil from the factory.
^ For a new adjustment of the gear set, the drive pinion adjustment must now be performed with checks.