Audi Workshop Service and Repair Manuals

Adjusting crown wheel (Adjusting differential)   Note The crown wheel only needs to be re-adjusted according to the following instructions if the gearbox housing, cover for final drive, tapered roller bearings for differential, differential cage or final drive gear set are being renewed. Table of adjustments → Anchor.

Special tools and workshop equipment required

t	Drift -VW 295-

t	Measuring tool -VW 382-

t	Universal measuring tool -VW 385-

t	Universal dial gauge bracket -VW 387-

t	Adjustable measuring lever -VW 388-

t	Thrust plate -VW 402-

t	Removal and installing tool -VW 459-

t	Crown wheel adjusting tool -VW 521-

t	Thrust plate -30-205-

t	Mandrel -30-505-

t	Thrust pad -3062-

t	Dial gauge

t	Dial gauge extension

Determining total shim thickness “Stotal” for shims “S1”  + “S2” (Adjustment of pre-load of tapered roller bearings for differential) l  Pinion shaft removed. –  Remove oil seal for flange shaft and outer races of both tapered roller bearings for differential. –  Remove shims → Item. –  Drive outer race for tapered roller bearing with shim “S2” into gearbox housing. For measurement purposes an “S2*” shim 1.20 mm thick (2 shims of 0.60 mm) is used.   Note For measurement purposes a shim “S2” with a thickness of 1.20 mm is fitted provisionally. It is referred to below as “S2*”. After determining the backlash “S2*” will be replaced with the correct “S2”.

–  Press outer race for tapered roller bearing without shim “S1” into cover for final drive. –  Insert differential without drive wheel for speedometer sender -G22- into gearbox housing. The crown wheel is positioned on the left-hand side, in front of cover for final drive. –  Fit cover for final drive and tighten bolts to 25 Nm. –  Position gearbox so that cover for final drive faces up. –  Turn differential 5 turns in both directions so that the tapered roller bearings settle.

–  Set up measuring tool with 30 mm dial gauge extension -A-. –  Set dial gauge (3 mm measuring range) to “0” with 2 mm preload. l  Tip of dial gauge must be located at centre of differential. –  Raise differential without turning, read play off dial gauge and note down (example: 0.62 mm).   Note

t  Secure crown wheel adjusting tool -VW 521/4- and -VW 521/8- on right of differential (housing side) to lift differential. t  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

Example:
Installed shim(s) “S2*”	1.20 mm
Dial gauge reading (example)	+ 0.62 mm
Bearing preload (constant value)	+ 0.25 mm
Total shim thickness “Stotal” for shims “S1” + “S2”	= 2.07 mm

Determining thickness of shim “S1*”   Note t  The provisional shim “S1*” will be replaced with the final shim “S1” after determining the backlash. t  Total shim thickness “Stotal” remains unchanged.    Formula: “S1*” = “Stotal” – “S2*”

Example:
Total shim thickness “Stotal” for shims “S1” + “S2”	2.07 mm
Installed shim(s) “S2*”	– 1.20 mm
Thickness of shim “S1*”	+ 0.87 mm

Measuring backlash (Position of crown wheel in gearbox housing) l  Pinion shaft with shims “S3” and “S4” installed. –  Fit differential with shims “S1*” and “S2*”. –  Fit cover for final drive and tighten bolts to 25 Nm. –  Turn differential 5 turns in both directions so that the tapered roller bearings seat properly.

–  Set up measuring tool, use dial gauge extension -VW 382/10- (6 mm, flat). –  Insert crown wheel adjusting tool -VW 521/4- and -VW 521/8-. –  Set measuring lever, adjustable -VW 388- to dimension “a” = 79 mm. 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 another 3 times.   Note 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; renew final drive gear set if necessary. Determining average backlash –  Add the 4 measured values together and divide by 4.

Example:
1st measured value	0.49 mm
2nd measured value	+ 0.48 mm
3rd measured value	+ 0.50 mm
4th measured value	+ 0.49 mm
Sum of measured values	= 1.96 mm

l  Result: the average backlash is 1.96 mm : 4 = 0.49 mm. Determining thickness of shim “S2”    Formula: “S2” = “S2*” – backlash + lift

Example:
Installed shim(s) “S2*”	1.20 mm
Average backlash	– 0.49 mm
Lift (constant value)	+ 0.15 mm
Thickness of shim “S2”	= 0.86 mm

–  Select thickness of required shim(s) from following table:

Available shims - Thickness of shims in mm 1)2)
0.45	0.65	0.85
0.50	0.70	0.90
0.55	0.75
0.60	0.80
l  1) Part numbers → Parts catalogue. l  2) 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”

Example:
Total shim thickness “Stotal” for shims “S1” + “S2”	2.07 mm
Inserted shim “S2”	– 0.86 mm
Thickness of shim “S1”	= 1.21 mm

–  Select thickness of required shim(s) from following table:

Available shims - Thickness of shims in mm 1)2)
0.45	0.65	0.85
0.50	0.70	0.90
0.55	0.75
0.60	0.80
l  1) Part numbers → Parts catalogue. l  2) The exact shim thickness required can be obtained by using the shim tolerance variations. Install two shims if necessary.

Checking adjustment –  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. l  Specification: 0.12 ... 0.22 mm   Note t  Adjustment must be repeated if backlash is outside tolerance. The total shim thickness “Stotal” must remain unchanged. t  The discrepancy between individual measured values must not exceed 0.06 mm.