1999 AUDI A4 differential

39-41


Speedometer Vehicle Speed
Sensor (VSS), removing and
installing

Total shim thickness Stotal for
shim S3 + S4, determining
Adjust preload of tapered roller bearings for
pinion shaft with hollow shaft

Differential removed

Note:
Illustration shows hollow shaft without gears. The adjustment of the pinion
shaft can be done with or without gears. - Press inner race -1- for double tapered roller bearing onto pinion shaft
and secure Page 35
-21
.
- Position needle bearing -2-.
- Install circlip 3 onto hollow shaft and press on inner race for tapered
roller bearing -4- Page 35
-21
.
- Insert pinion shaft in hollow shaft.
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39-48


Note:
Make sure gauge contact surface is precisely installed and free of oil. - Place end gauge on face of pinion shaft.

- Remove master gauge and install measuring mandrel into transmission
housing.
Dial indicator extension -A- = 6.5 mm long must be installed. The VW385/3 centering disc faces cover for final drive
- Install differential cover and tighten 4 bolts to 22 Nm (16 ft lb).
- Using adjustable ring, pull 2nd VW385/3 centering disc out as far as
possible, so mandrel can only just be turned by hand.
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39-57

Ring gear, adjusting


Adjusting differential
For a list of the repairs which will require the ring
gear to be adjusted table, Page 39
-37
.

Special tools and equipment

VW382/10 extension pin
VW385/17 magnetic plate
VW386A clamping piece
VW387 dial indicator holder
VW388 measuring lever
VW402 thrust plate
VW408A punch
VW472/1 pressure piece
VW521 adjustment tool
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39-58

Determining total shim thickness "Stotal" (S1
+ S2)
Adjusting preload of tapered roller bearings for
differential

Pinion shaft removed

Note:
If only the tapered roller bearings for the
differential are being replaced, the ring gear can
be removed from the differential housing. The
pinion shaft does not have to be removed.

- Remove seals and outer races of both tapered
roller bearings for differential.

- Remove shims Page 39
-21
.

Note:
For measurement purposes, a shim S2 of 1.20 mm is initially inserted and
referred to as S2* in the following text. After determining backlash, S2* will
be replaced by the correct shim S2. - Press right tapered roller bearing outer race with shim S2 into
transmission housing Fig. 2, Page 39
-27
. Shim S2* with thickness
of 1.20 mm (two 0.60 mm shims) is used for initial measurement.
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39-59


- Press tapered roller bearing outer race into differential cover without
shim S1 Fig. 8, Page 39
-31
.
- Insert differential without speedometer gear drive into transmission
housing. Ring gear is positioned on left-hand side infront of final drive
cover.
- Install differential cover with 4 bolts and tighten to 25 Nm (18 ft lb).
- Position transmission so differential cover faces upward.
- Turn differential 5 turns in both directions so tapered roller bearings
settle.

Note:
The tip of the dial indicator must be positioned on the center of the
differential. - Assemble measuring equipment, using 30 mm dial indicator extension.
- Set dial indicator (3 mm measuring range) -A- to "0" with 2 mm
preload.
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39-60

- Lift differential without turning, and read off play
on dial indicator.

Measurement in following example: 0.62 mm

Notes:

To lift the differential, attach VW521/4 locking sleeve and VW521/12
on the right of the differential (housing side). If the measurement has to be repeated, the pinion shaft with hollow
shaft must be turned 5 turns in each direction first to settle the tapered
roller bearing.
Formula:
Stotal
=
S2*- + measurement + bearing preload
Example

Inserted shim(s) S2* 1.20 mm
+ Measured value 0.62 mm
+ Bearing preload (constant value) 0.30 mm
= Total thickness Stotal for S1 + S2 2.12 mm
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39-62

Measuring friction torque

Notes:

Differential tapered roller bearings are low
friction bearings. Therefore the friction torque
only has a limited use as a check. Correct
adjustment is only possible by determining the
total shim thickness Stotal.
Do not additionally oil new tapered roller
bearings for friction torque measurement. The
bearings have already been treated with a
special oil by the manufacturer.
Pinion shaft removed

Friction torque specifications:
Note: - Install torque gauge 0-600 Ncm (53 in. lb) -A- onto differential.
B - Socket
- Read friction torque.
New bearings
Used bearings
150-350 Ncm (13-31 in. lb) 30-60 Ncm (3-5 in. lb)
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39-63

Measuring backlash
Position of ring gear in transmission housing

Pinion shaft with shims S3* and S4* installed

- Install differential.

- Turn differential 5 turns in each direction to
settle tapered roller bearings.

- Secure VW387 dial indicator holder onto housing.
- Attach VW521/4 locking sleeve and VW521/12.
- Install dial indicator and VW382/10 extension pin (6 mm flat).
- Adjust VW388 measuring lever to dimension -a-:
Distance -a-: 67 mm (2.637 in.) for 170 mm (6.693 in.) diameter ring
gear.
- Determine play between teeth flanks as follows:
- Turn ring gear until it makes contact with tooth flank (end of backlash
travel).
- Set dial indicator to "0" with 2 mm preload.
- Turn ring gear back against opposite tooth flank (backlash).
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11/20/2002 htt
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play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.TM02.39.7