Final Drive, Adjusting When Replacing Differential Or Differential Bearing

Special tools and workshop equipment required

Dial Indicator : VAS 6080A
: VW 204 B
Ring Gear Locking Sleeve : VW 521/4
Crown Wheel Adjusting Tool : VW521
Ring Gear Locking Sleeve :VW521/4
Crown Wheel Adjusting Tool :VW 521
Crown Wheel Adjusting Tool :VW 521
Positioning Tolerance Shell :VW521/13
Positioning Tolerance Shell : VW 521/13
Drive Axle Wedge Tool :T10161
Measuring Lever :VW388
Measuring Set - End Gauge :VW 385/33
Dial Gauge
Dial Gauge Extension
Dial Indicator Holder :VW 387

Careful adjustment of the differential is important for service life and smooth running of final drive.
Adjusting the final drive (differential) is required if the differential and the differential bearing are being replaced.
The drive pinion remains installed, for this reason the adjustment backlash must always be achieved. Otherwise the drive train will be damaged!
The transmission is secured to the assembly stand and the flywheel with the right flange shaft is removed.

The total shim thickness S_total for the shims S₁ + S₂ , determining

-- Remove the outer race for the left tapered roller bearing from the transmission housing. Refer to Differential, Disassembling and Assembling .

-- Drive the new outer race for left tapered roller bearing with the old shim "S₂ " with the example thickness of 1.05 mm into the transmission housing.

Fig 1: Driving Outer Race For Tapered Roller Bearing With Shim Into Transmission Housing

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Conditions

For the initial measurement, install the old shim S₂ with a thickness for example of 1.05 mm. This will be indicated by "S₂ *" in the following. After determining the torsional backlash, "S₂ *" is replaced by final "S ₂ ".

-- Press in the new outer race for the right angular contact ball bearing with the old shim "S ₁ " in for example of 1.21 mm in the final drive cover. The larger diameter of the Seal Installer - Crankshaft :VW 204 B faces the outer race.

Fig 2: Identifying Outer Race Tapered Bearing, Installation

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-- Insert the differential into the transmission housing.

Tip

Check the torsional backlash when tightening the final drive cover. Some play must always be present.
If the transmission is disassembled, the play at the pinion can be checked by turning back and forth.
If transmission is not disassembled, insert the Crown Wheel Adjusting Tool : VW521 and check play.

-- Fasten the final drive cover carefully with four bolts diagonally to 20 Nm.

-- Place the Positioning Tolerance Shell :VW 521/13 with the smaller outer diameter -arrow- on the Ring Gear Locking Sleeve : VW 521/4 .

Fig 3: Crown Wheel Adjusting Tool VW521

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-- Insert the Crown Wheel Adjusting Tool :VW 521 and turn the differential five turns each in both directions, so that the bearings set.

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

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-- Remove the Crown Wheel Adjusting Tool :VW 521 and install the measuring tools on the transmission housing as follows:

Fig 5: Checking Tapered Roller Bearing Pre-Load

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-- Attach the Dial Gauge Holder :VW 387 to the threaded hole in the transmission housing with the bolt -A-.

-- Place the Dial Gauge Extension on the center of the Measuring Set - End Gauge :VW 385/33 .

-- Set the dial gauge for example Dial Indicator :VAS 6080A to "0" with 1 mm of pretension.

-- Loosen the four bolts -arrows- diagonally one turn.

-- Read the measured value on the dial gauge.

Conditions

Specified value: 0.25 to 0.30 mm

-- If the measure value is not obtained or no torsional backlash is felt, then correct the thickness of the shims "S₁ " and "S₂ ".

Conditions

Allocate adjustment shims according to the Electronic Parts Information (ETKA).

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.

Fig 6: Inserting Adjusting Tool VW521/4 And VW521/13 Into Differential

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-- 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-

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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.

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-- To do this, remove the transmission housing. Refer to Transmission Housing, Removing and Installing .

-- 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.

Average Torsional Backlash, Determining

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

Example:
	1. Measured value	0.23 mm
+	2. Measured value	0.24 mm
+	3. Measured value	0.22 mm
+	4. Measured value	0.23 mm
=	Total of the measured values	0.92 mm

Conditions

Results: the center torsional backlash is 0.92 mm: 4 = 0.23 mm

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

Determining the thickness of the shim S₂

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

Determining the thickness of the shim S₁

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

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.

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-- Measure backlash on the circumference four times.

Specified value: 0.15 ± 0.04 mm

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

Conditions

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