Checking axial clearance of Torsen differential and adjusting — AUDI

Note:

The Torsen differential axial clearance must be checked and readjusted if necessary when the front intermediate drive, the Torsen differential, the rear intermediate drive or parts of these assemblies (e.g. housing, bearings, gears, shims) are renewed.

Special tools and workshop equipment required

Depth gauge (with digital display and at least a 220 mm wide contact surface if possible).
Micrometer (measuring range: 0 - 25 mm)

Checking axial clearance of Torsen differential

Remove front intermediate drive => Page
39-46
.
Dismantle front intermediate drive => Page
39-62
.
Unbolt transfer gearbox from front intermediate drive => Page
39-90
.
Insert input gear (=> -Item
39-44
) with bearing into housing of front intermediate drive.
Fit intermediate flange (=> -Item
39-39
) with prescribed tightening torque to housing of front intermediate drive.

Note:

The transfer gearbox must be separated from the front intermediate drive.

The axial clearance "c" of the Torsen differential is checked with the thrust washer "S" of the output cup installed.

Formula:
"c" · = · "a" - "b"
a · = · measured value => Page 39-107
b · = · measured value => Page 39-109

Determining dimension "a"

Check flange joint of intermediate drive to transfer gearbox for damage to provide a smooth contact surface for depth gauge.

Place tip of depth gauge onto bearing inner race -1- of input gear.
Measure at 4 different points on the bearing race and note measured values.

Note:

If the difference between the 4 measured values is more than 0.10 mm, the installation of the input pinion or the contact surface for the depth gauge on the housing is not in order. Rectify problem and repeat measurements.

Add the four measured values together and divide by four.

Example:
1st measured value · 41.35 mm
+ · 2nd measured value · 41.32 mm
+ · 3rd measured value · 41.39 mm
+ · 4th measured value · 41.33 mm
= · Sum of measured values · 165.39 mm

Result: the average dimension "a" is
165.39 mm /4 = 41.35 mm

Determining dimension "b"

Check seat of thrust washer "S" for output cup.
Secure thrust washer on output cup with Vaseline and insert together up to stop on rear axle shaft.

Note:

The thrust washer can slip out of the cut-out in the output cup if not inserted carefully. This will alter the axial clearance of the Torsen differential.

Place transfer gearbox on workbench so that hub is pointing exactly upwards.

Check flange and hub -1- for damage to ensure a smooth contact surface for depth gauge.

Notes:

Do not load the hub in the direction of the arrows when measuring, as otherwise the measurement will be falsified.
Do not place the contact surface of the depth gauge in the recesses on the hub.
Measure at 4 different points and note measured values.

Add the four measured values together and divide by four.

Example:
1st measured value · 40.70 mm
+ · 2nd measured value · 40.80 mm
+ · 3rd measured value · 40.75 mm
+ · 4th measured value · 40.78 mm
= · Sum of measured values · 163.03 mm

Result: the average dimension "b" is
163.03 mm / 4 = 40.76 mm

Determining axial play "c" of Torsen differential

Formula:
"c" · = · average dimension "a" - average dimension "b"

Example:
average dimension "a" · 41.35 mm
- · average dimension "b" · 40.76 mm
= · Value "c" · 0.59 mm

Axial clearance specification: 0.2 - 0.7 mm

Result: in the example shown, the determined axial clearance for the Torsen differential (value "c") is, with thrust washer "S" installed, within the permissible tolerances.

If the determined axial clearance is outside the permissible tolerances, the axial clearance must be adjusted => page
39-112
.

If the determined axial clearance is within the permissible tolerances, install Torsen differential => page
39-114
.

Adjusting axial clearance for Torsen differential

The axial clearance for the Torsen differential is set with different thicknesses of thrust washer "S" of the output cup.

Determine axial clearance "c" for Torsen differential => page
39-105
.
Remove thrust washer "S".
Measure thickness of previously removed thrust washer "S" using a micrometer and note thickness.

Note:

When readjusting the axial clearance "c", aim for a specification of 0.5 mm.

Determining thickness of new thrust washer "S"

Formula:
Determined axial clearance "c" / of Torsen differential
- · Specification for axial clearance "c"
+ · Thickness of previous thrust washer "S"
= · Thickness of new thrust washer "S"

Example:
Determined axial clearance "c" / of Torsen differential · / 0.95 mm
- · Specification for axial clearance "c" · 0.50 mm
+ · Thickness of previous thrust washer "S" · / 2.00 mm
= · Thickness of new thrust washer "S" · / 2.45 mm

Determine thrust washer(s) from table. Part numbers

=> Parts catalogue

Note:

Select the relevant thrust washer that is closest to the thickness of the new thrust washer. Example: if 2.45 mm is determined, use a thrust washer with a thickness of 2.50 mm.

Measure new thrust washer at several points on circumference with a micrometer.
Install new thrust washer and check axial clearance of Torsen differential => Page
39-105
.

Installing

Installation is carried out in the reverse order. When doing this, note the following:

Assemble front intermediate drive => Page
39-64
.
Install transfer gearbox =>Page
39-93
.
Install front intermediate drive => Page
39-58
.