Audi Workshop Service and Repair Manuals

Adjusting bevel gear It is necessary to readjust the bevel gear when the following components have been renewed: t  Final drive housing t  Cover t  Tapered roller bearings for bevel gear with input shaft t  Final drive gear set Table of adjustments → Anchor.

Special tools and workshop equipment required

t	End measuring plate -VW 385/17-

t	Universal dial gauge bracket -VW 387-

t	Adjustable measuring lever -VW 388-

t	Crown wheel adjusting tool -VW 521/4-

t	Crown wheel adjusting tool -VW 521/13-

t	Dial gauge

Adjusting preload of tapered roller bearings for bevel gear (friction torque) l  Shaft bevel gear removed. –  Insert 1.2 mm shim in seat of small tapered roller bearing outer race (“S2” side).   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 by the correct shim “S2”. –  Press in outer race → Anchor. –  Fit bevel gear with input shaft together with taper roller bearing. –  Install cover with large tapered roller bearing outer race but without O-ring, drive flange oil seal and without shim “S1”. –  Press bevel gear with input shaft towards cover and turn eight times. –  Press bevel gear with input shaft towards small tapered roller bearing outer race and turn eight times.

–  Fit dial gauge with 30 mm dial gauge extension -item A-. –  Set dial gauge to “0” with a preload of 2 mm. –  Move bevel gear with input shaft up and down -double-ended arrow-. –  Read off and note play indicated on dial gauge (in this example: 0.45 mm) and calculate “Stotal”.    Formula: “Stotal” = “S2*” + measured value + preload

Example:
Installed shim(s) “S2*”	1.20 mm
Dial gauge reading (example)	+ 0.45 mm
Preload (constant value)	+ 0.30 mm
“Stotal”	= 1.95 mm

Determining thickness of provisional shim “S1*”   Note t  The provisional adjustment 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”	1.95 mm
Installed shim(s) “S2*”	– 1.20 mm
Thickness of shim “S1*”	= 0.75 mm

The following shims are available for “S1” → Anchor. Measuring backlash l  Pinion housing with shaft bevel gear and “S3” installed –  Install bevel gear with input shaft: “S1*” is fitted on cover side, “S2*” in final drive housing.

–  Fit measuring tools with dial gauge extension, approx. 25 mm as shown in the illustration. l  Dimension -a- = 39 mm l  Screw in measuring lever -VW 388- so that the dial gauge extension is at right angles to the measuring face. –  Rotate bevel gear with input shaft until stop. Set dial gauge to “0”, turn bevel gear with input shaft back and read off backlash. Note this value. –  Loosen locking screw on clamping sleeve and turn bevel gear with input shaft through a further 90°. Then repeat complete measuring process a further 3 times. Add up the four measured values and calculate the average backlash. Calculating average backlash

Example:
	1st measured value	0.45 mm
+	2nd measured value	0.44 mm
+	3rd measured value	0.45 mm
+	4th measured value	0.46 mm
Total		1.80 mm

Average backlash = 1.80 mm : 4 = 0.45 mm. Determining thickness of shim “S2” Formula: “S2” = “S2*” – average backlash + lift (constant value)

Example:
Installed shim(s) “S2*”	1.20 mm
Average backlash	– 0.45 mm
Lift (constant value)	+ 0.20 mm
Shim “S2”	= 0.95 mm

–  Select required shim thickness from following table:

Available shims - Thickness of shims in mm 1)2)
0.15	0.50	0.90
0.20	0.60	1.20
0.30	0.70
0.40	0.80
l  1) For Part No. refer to → Parts catalogue. l  2) Tolerance variations make it possible to obtain the exact shim thickness required.

–  Install determined shim(s) “S2” instead of “S2*”. –  Press outer race in again and install bevel gear with input shaft. Determining thickness of shim “S1” Formula: “S1” = “Stotal” – “S2”

Example:
Total shim thickness “Stotal”	1.95 mm
Installed shim(s) “S2”	– 0.95 mm
Thickness of shim “S1”	= 1.00 mm

–  Select required shim thickness from following table:

Available shims - Thickness of shims in mm 1)2)
0.70	0.95	1.20
0.75	1.00	1.25
0.80	1.05	1.30
0.85	1.10	1.35
0.90	1.15
l  1) For Part No. refer to → Parts catalogue. l  2) Tolerance variations make it possible to obtain the exact shim thickness required.

–  Install determined shim(s) “S1”. –  Press outer race back in. –  Install cover. Checking adjustment - measuring backlash –  Measure backlash. l  Specification: 0.15 ... 0.20 mm