Torsional Backlash, Measuring

• Pinion is installed with shims "S₃ " and "S₄ ". Refer to PINION, REMOVING AND INSTALLING .
• The output gear of the spur gear unit as well as the parking lock gear are removed. Refer to Figure.
• O-ring is inserted in final drive cover.

-- Install the differential with shim: "S ₁ *" is on the cover side, "S ₂ *" is installed in the transmission housing.

-- Install the final drive cover and tighten the four bolts to 20 Nm.

-- Complete the Crown Wheel Adjusting Tool :VW 521  and insert it in the differential.

-- Turn the differential five turns in both directions so that the bearings settle.

-- Attach the Dial Gauge Holder: VW 387  -6- to the final drive cover -arrow-

1. Dial Indicator:VAS 6080A 
2. Dial Gauge Extension (8 cm plan)
3. Measuring Lever:VW388 
4. Ring Gear Locking Sleeve:VW521/4 
5. Positioning Tolerance Shell:VW521/13 
6. Dial Indicator Holder:VW 387 

-- Insert the Dial Gauge for example Dial Indicator: VAS 6080A  using the Dial Gauge Extension (8 cm plan).

-- Adjust the Measuring Lever:VW 388  to the dimension -a- = 79 mm (for the ring gear 196 mm).

So that an exact torsional backlash can be measured, the pinion must be locked.

-- To do so remove the bolt -1-.

-- Place on the threaded hole washer or with a nut (for example M12) -2-.

• The dimension -a- must be at least 14 mm.

Locking the pinion 1

2 -

M8 x 110 Bolt or M8 x 130 Threaded Rod with M8 Nut

3 -

Clamping Piece:VW386A 

-- Lock the pinion -1- with the bolt -arrow- from the Clamping Piece:VW 386A  .

Determine the play between the tooth flanks as follows:

-- Turn ring gear until it makes contact with a tooth flank (end of backlash travel).

-- Set the dial gauge to "0" with 2 mm pretension.

-- Turn ring gear back until lying against an opposite tooth flank (backlash).

-- Read the torsional backlash and write down the measured value.

-- Turn the ring gear 90° and repeat measurements three more times. Loosen the Clamping Piece:VW 386A  to additionally tighten.

Average Torsional Backlash, Determining

-- Add the four measured values and then divide the total by 4.

Example:
	1. Measured value	0.55 mm
+	2. Measured value	0.54 mm
+	3. Measured value	0.55 mm
+	4. Measured value	0.56 mm
=	Total of the measured values	2.20 mm

• Results: the average torsional backlash is approximately 2.20 mm: 4 = 0.5 mm

Shim Thickness "S₂ ", Determining

Formula: "S₂ " = "S₂ *" - measured torsional backlash + specified torsional backlash

Example:
	Old shim "S 2 *"	1.17 mm
-	Measured average torsional backlash	0.55 mm
+	Specified torsional backlash (desired average value for the torsional backlash)	0.15 mm
=	Shim thickness "S 2 "	0.77 mm

Determine the shim according to the table. Refer to the Parts Information for the part number.

Adjusting Shims Available for

Shim thickness (mm)
0.37	0.65	0.93	1.21	1.49
0.41	0.69	0.97	1.25	1.53
0.45	0.73	1.01	1.29	1.57
0.49	0.77	1.05	1.33	1.61
0.53	0.81	1.09	1.37	1.65
0.57	0.85	1.13	1.41
0.61	0.89	1.17	1.45

Tolerance variations make it possible to find the exact shim thickness required.

Shim Thickness "S ₁ ", Determining

Formula: "S ₁ " = "S _total " - "S ₂ "

Example:
	Total shim thickness "S total " for "S 1 " + "S 2 "	2.22 mm
-	Shim thickness "S 2 "	0.77 mm
=	Shim thickness "S 1 "	1.45 mm

-- Determine the shim according to the table. Refer to the Parts Information for the part number.

Shim thickness (mm)
0.65	0.89	1.13	1.37	1.61
0.69	0.93	1.17	1.41	1.65
0.73	0.97	1.21	1.45	1.69
0.77	1.01	1.25	1.49	1.73
0.81	1.05	1.29	1.53	1.77
0.85	1.09	1.33	1.57	Courtesy of AUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLC Courtesy of AUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLC Courtesy of AUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLC Courtesy of AUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLC Courtesy of AUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLCAUDI OF AMERICA, LLC

Adjusting Shims Available for 

Tolerance variations make it possible to find the exact shim thickness required.

-- Remove the old shims "S ₁ *" and "S ₂ *" and install the newly determined shims. Refer to OVERVIEW - DIFFERENTIAL .

Measurement check

-- Turn the differential five turns in both directions after installing the shims "S ₁ " and "S ₂ " so that the tapered roller bearings can settle.

-- Measure backlash on the circumference four times.

• Specified value: 0.15 ± 0.04 mm

1. Dial Indicator:VAS 6080A 
2. Dial Gauge Extension (8 cm plan)
3. Measuring Lever:VW388 
4. Ring Gear Locking Sleeve:VW521/4 
5. Positioning Tolerance Shell:VW521/13 
6. Dial Indicator Holder:VW 387 

• If the torsional backlash is outside of the tolerance, then repeat the adjustment. Total shim thickness "S _total " may not be changed.