Torsional Backlash, Measuring

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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.

CAUTION:

Danger of causing damage to the gear set.

Check the torsional backlash when tightening the final drive cover. Some play must always be present.
The play can be checked on the pinion by turning back and forth.

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

-- Complete the Crown Wheel Adjusting Tool:VW 521 (refer to Complete the as follows: ) and insert it in the differential.

Fig 1: Inserting Adjusting Tool VW521/4 And VW521/13 Into Differential

Courtesy of AUDI

-- 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-

Courtesy of AUDI

Dial Indicator:VAS 6080A
Dial Gauge Extension (8 cm plan)
Measuring Lever:VW388
Ring Gear Locking Sleeve:VW521/4
Positioning Tolerance Shell:VW521/13
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-.

Courtesy of AUDI

-- 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

Fig 2: Locking the Pinion -1-

Courtesy of AUDI

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 appropriate Electronic Parts Information for the part number.

Fig 3: Slide off the Output Gear -1- of the Drive Wheel from the Pinion.

Courtesy of AUDI