Determining Disc Thickness S1 and S2
Determining disc thickness S1 and S2Note!
^ The crown wheel must be adjusted again if the transmission housing, the side cover, the tapered roller bearing for the differential, the differential housing or the drive set are replaced.
Determining disc thickness S1 + S2
1. Remove the tensioning plate with the input and output shafts.
2. Insert 2 discs S1 and S2 with a thickness of 2.5 mm each into the differential and mount the tapered roller bearing.
Note!
^ The chamfers of the adjusting shims point towards the housing.
3. Insert the differential into the housing and turn it several times.
4. Mount the side transmission cover without a shaft seal and screw in all screws.
Tightening torque: 25 Nm (19 ft. lbs.)
5. Fit special tool adjustment device VW 521/4 opposite the crown wheel side (S2 side) into the differential.
6. Place the special tool end plate VW 385/17 -B- on to the differential.
7. Fasten special tool dial gauge holder VW 387 on the housing with the dial gauge and the special tool dial gauge extension VW 385/56 -A-.
8. Set dial gauge with 2 mm pretension to 0.
9. Press the differential upwards as far as possible with special tool adjustment device VW 521/4.
10. Read off the play on the dial gauge.
Example: 0.75 mm
Note!
^ The differential must not be turned during the measurement, as otherwise the measurement will be falsified.
11. The total thickness of discs S1 and S2 is calculated from the total of the already inserted discs plus the measured value plus the specified bearing pretension of the tapered roller bearing.
Example: 5.00 mm + 0.75 mm + 0.40 mm = 6.15 mm = S1 + S2
Note!
^ The pretension of the tapered roller bearing in this transmission is always 0.40 mm.
Dividing the total disc thickness into S1 and S2
Note!
^ In order to gain as precise a setting of the backlash as possible at this point, the adjusting shim S1 must be 1.4 mm thicker than adjusting shim S2.
Example: disc thickness S1 = 6.15 mm / 2 - 0.7 mm = 2.375 mm
Example: disc thickness S2 = 6.15 mm / 2 + 0.7 mm = 3.775 mm
Note!
^ As the adjusting shims are available in thicknesses from 1.5 to 2.8 mm in increments of 0.05 mm, the calculated result must be rounded off. However, the total of the disc thicknesses S1 + S2 must not be changed. To determine the thickness, measure the adjusting shims at several places with a micrometer.
The discs should also be checked for burrs and damage.
Example: disc thickness S1 = 2.375 mm; inserted adjusting shim = 2.35 mm
Example: disc thickness S2 = 3.775 mm; inserted adjusting shim = 3.80 mm
Example: total of both inserted discs = 2.35 + 3.80 = 6.15
1. Remove the differential and pull off both tapered roller bearings.
2. Insert the calculated adjusting shims S1 and S2.
Checking the circumferential backlash and setting, if necessary
1. Read off the backlash at the crown wheel.
1 Installation dimension E
2 Backlash F
3 Matching number
2. Mount the input and output shafts with tensioning plate and adjusting shims.
Tightening torque: 25 Nm (19 ft. lbs.)
3. Mount the gear set and the gear housing. Then assemble front gear set.
4. Screw collar nut on to the output shaft.
Tightening torque: 300 Nm (222 ft. lbs.)
5. Install the differential and mount the side transmission cover with all the screws.
Tightening torque: 25 Nm (19 ft. lbs.)
Note!
^ Always make sure a certain amount of backlash is present when tightening the screws. The drive pinion must not jam under any circumstances.
6. Screw in special tool gauge plunger VW 388 with special tool adjustment device VW 521/4 and set the lever length to 91 mm -a-.
7. Insert special tool adjustment device VW 521/4 into the differential with special tool bushing 9145 and clamp tight.
8. Turn the differential several times in both directions so that the tapered roller bearings can settle.
9. Mount the special tool dial gauge holder VW 387 with the dial gauge in such a way that a right angle is formed between the dial gauge axis and the special tool gauge plunger VW 388.
10. Install special tool retaining device 9562.
11. Turn the crown wheel as far as it will go via the clamping screw of the special tool adjustment device VW 521/4 and set the dial gauge to zero.
12. Turn the crown wheel back and read off the circumferential backlash.
13. This measurement should be performed a further three times. The crown wheel must be turned 90° before every measurement. The difference between the four measurements must not exceed 0.03 mm. Moreover, none of the measurements may deviate by more than 0.04 mm from the circumferential backlash noted on the crown wheel. If any of the specified dimensions is not observed, the adjusting shims S1 and S2 must be replaced again.
Note!
^ The total disc thickness S1 + S2 must not be changed.