Torsional Backlash, Measuring

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

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

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-- 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-

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-- Insert the Dial Gauge for example: VAS 6080A using the Dial Gauge Extension (8 cm (3.15 in.) plan).

-- Adjust the Measuring Lever: VW 388 to the dimension -a- = 79 mm (3.11 in.) (for the ring gear 196 mm (7.72 in.)).

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

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-- To do so remove the transmission cover. Refer to OVERVIEW - TRANSMISSION HOUSING .

-- Insert the Drive Axle Wedge Tool : T10161 between the output gear -1- for the spur gear unit and transmission housing.

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. To continue turning, remove the Drive Axle Wedge Tool: T10161 from between the output gear for the spur gear unit and the transmission housing. Refer to Torsional Backlash, Measuring - Insert the Drive Axle Wedge Tool: T10161 between the output gear -1- for the spur gear unit and transmission housing. .

Average Torsional Backlash, Determining

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

Shim Thickness "S₂ ", Determining

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

Example:
	Old shim "S ₂ *"	1.05 mm
-	Measured average torsional backlash	0.23 mm
+	Specified torsional backlash (desired average value for the torsional backlash)	0.15 mm
=	Shim thickness "S ₂ "	0.97 mm

Available shims "S ₂ " Adjusting Shims Available for "S 2 " ; for the part number, refer to the Parts Information.

Shim Thickness "S ₁ ", Determining

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

Example:
	Total shim thickness "S _total " for "S ₁ " + "S ₂ "	2.26 mm
-	Shim thickness "S ₂ "	0.97 mm
=	Shim thickness "S ₁ "	1.29 mm

Available shims "S ₁ " Adjusting Shims Available for "S 1 " ; for the part number, refer to the Parts Information.

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

Measurement check

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-- 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.

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