Adjusting the Ring Gear and Pinion Shaft
Adjusting the ring gear and pinion shaft
Tools and materials
Tools
General warning notes
Purpose of adjustment operations
Careful adjustment of the output shaft and crown wheel are crucial to the service life and smooth running of the final drive. Therefore, output shafts and crown wheels are paired with each other as early as during production and are checked by special machines to ensure a good position of the contact pattern and that there is low noise in both rotation directions.
Adjustment overview
Adjustment overview
When carrying out assembly work on the final drive, re-adjustment of the output shaft and crown wheel or ring gear and pinion shaft is necessary only if parts are being replaced which directly influence the adjustment of the final drive. To avoid unnecessary adjustment work, follow the table below:
Sequence of adjustment operations
Adjustment overview
If the pinion shaft and crown wheel have to be adjusted, it is best to follow the sequence below in the interest of rational working:
1. Determine the total shim thickness -S1- + -S2-.
2. Determine the total shim thickness -S3- + -S4-.
3. Divide the total shim thickness -S3- + -S4- into -S3- and -S4-.
4. Determine shim thickness -S5-.
5. Determine shim thickness -S6-.
6. Divide the total shim thickness into -S1- and -S2-.
7. Check the circumferential backlash and adjust it if necessary.
Preliminary work
1. Remove transmission.
2. Drain transmission oil.
3. Disassemble the transmission.
Determining total shim thickness S1 + S2
Information
^ The output shaft must be removed in order to determine the total shim thickness -S1- + -S2-.
^ Before beginning adjusting and measuring work, the sealing surfaces of the transmission housing and cover must be cleaned carefully.
Adjustment overview
1. Insert 1.5-mm adjusting shims -S1- and -S2- under the taper roller bearings and fit taper roller bearings.
2. Insert differential in transmission housing.
3. Fit the transmission cover without a shaft sealing ring and screw in screws.
Tightening torque 25 Nm (19 ftlb.)
4. Crown wheel adjusting tool VW 521/4 with bush 9145 must be fitted in the differential.
Fitting crown wheel adjusting tool with bush in differential
5. Measuring device, d=50 mm VW 385/17 must be positioned on the differential and universal dial gauge bracket VW 387 must be fitted before tensioning the dial gauge.
Fitting universal dial gauge bracket and tensioning dial gauge
6. Turn the differential a number of times at the crown wheel adjusting tool VW 521/4 and set dial gauge to 0 with 2 mm pretension.
7. Press the differential towards the transmission cover at the crown wheel adjusting tool VW 521/4 and read off the backlash on the dial gauge.
Reading off backlash on dial gauge
E.g.: 1.00 mm
8. The total thickness of shims -S1- + -S2- is calculated from the sum of the shims that are already inserted plus the measured value plus the specified bearing pretension of the taper roller bearings.
E.g.: 3.00 mm + 1.00 mm + 0.20 mm = 4.20 mm = S1 + S2
Information
The pretension of the taper roller bearings in this transmission is always 0.20 mm.
Determining total shim thickness S3 + S4
Information
The bearing pretension v1 for this bearing is always 0.20 mm.
1. Insert angular-contact ball bearing into measuring device 9694/8 (-sides B facing the bearing-) and tighten screw.
Inserting angular-contact ball bearing into measuring device
Tightening torque 10 Nm (7.5 ftlb.)
2. Measure dimension h1 between the turned groove and outer bearing ring using a micrometer.
Measuring dimension h1 between the turned groove and outer bearing ring using a micrometer
3. Measure the dimension at each cut-out on the measuring device 9694/8 and calculate the mean value.
Example:
^ Measurement 1: 34.40 mm
^ Measurement 2: 34.41 mm
^ Measurement 3: 34.39 mm
Bearing height h1 = 34.40 mm + 34.41 mm + 34.39 mm = 103.20 mm: 3 = 34.40 mm
4. Use a digital depth gauge to measure the depth of the bearing bore. To do this, measure the depth at three different places and calculate the mean value.
Using a digital depth gauge to measure the depth of the bearing bore
Example:
^ Measurement 1: 34.40 mm
^ Measurement 2: 34.44 mm
^ Measurement 3: 34.42 mm
Depth of bore T1 = 34.40 mm + 34.44 mm + 34.42 mm = 103.26 mm: 3 = 34.42 mm
5. Use a digital depth gauge to measure the depth of the turned groove in the tensioning plate. To do this, measure the depth at three different places and calculate the mean value.
Using a digital depth gauge to measure the depth of the turned groove in the tensioning plate
Example:
^ Measurement 1: 1.73 mm
^ Measurement 2: 1.82 mm
^ Measurement 3: 1.70 mm
Depth of groove t1 = 1.73 mm + 1.82 mm + 1.70 mm = 5.25:3 = 1.75 mm
Adjustment overview
The total shim thickness -S3- + -S4- is calculated as follows:
(-S3- + -S4-) = T1 + v1 + t1 - h1
Example:
^ h1 = 34.40 mm
^ v1 = 0.20 mm
^ t1 = 1.75 mm
^ T1 = 34.42 mm
(-S3- + -S4-) = 34.42 mm + 0.20 mm + 1.75 mm - 34.40 mm = 1.97 mm
Since the adjusting shims are available in thicknesses of 0.05 mm increments, this value must be rounded off accordingly. (-S3- + -S4-) = ~ 1.95 mm
Dividing the total shim thickness S3 + S4 into S3 and S4
1. Fit angular-contact ball bearing onto the output shaft.
2. Insert output shaft with angular-contact ball bearing and adjusting shim -S3- = 1.00 mm (empirical value) into the transmission housing.
Adjustment overview
3. Use the value (-S3- + -S4-) calculated in the previous section to work out the shim thickness -S4-.
Example: -S4- = 1.94 mm - 1.00 mm = 0.94 mm ~ 0.95 mm
4. Insert adjusting shim -S4- into the tensioning plate and tighten tensioning plate in the correct sequence.
Tightening sequence for tensioning plate screws
Tightening torque 32 Nm (24 ftlb.)
5. Adjust the setting collar on special tool measuring pin VW 385/1 to dimension -a- (approx. 60 mm).
Adjusting setting collar on measuring pin
6. Measuring pin VW 385/1 must be completed as shown in the illustration.
Completing measuring pin
7. Read off installation dimension E from the crown wheel.
Example: E = 61.55 mm
8. Set the installation dimension E on special tool adjustment gauge, 35-85 mm VW 385/30 and set the dial gauge to 0 with 2 mm pretension.
Information
^ The transmission must be allowed to cool down fully before starting to attach the measuring equipment.
9. Place special tool calliper VW 385/33 on the pinion head of the output shaft.
10. Insert measuring pin as shown in the illustration.
Inserting measuring pin
11. Fit the side transmission cover without an O-ring and pull downwards with screws. Do not tap down.
Tightening torque 26 Nm (19 ftlb.)
12. Press taper roller bearing with the centering screw over the spindle into the bearing shells. It should just be possible to turn the measuring pin by hand.
13. Turn the measuring pin carefully back and forth until the reversing point on the dial gauge is reached. At this point, the dial gauge extension is positioned exactly at a right angle to the front face of the pinion head.
14. Read off the deviation from the specified adjustment value E. If the deviation is greater than 0.04 mm, the adjusting shim must be corrected.
Example: 0.10 mm
Information
^ So in the example, the actual value of the adjusting dimension E would not be 61.55 but rather 61.65 mm.
15. In order to achieve the required adjustment dimension E, the adjusting shim -S3- must be changed by the measured value.
Example: New shim thickness -S3- = 0.90 mm
16. In order to adjust the altered shim -S3-, shim -S4- must be altered in the opposite direction by the determined value.
Example: -S4- = 1.05 mm (increase by 0.10 mm)
17. When the shims -S3- and -S4- have been corrected appropriately and inserted, the adjustment dimension E should be checked again.
Determining shim thickness S5
The thickness of the adjusting shim -S5- is calculated from the depth of the bearing bore T1, the thickness of adjusting shim -S3-, the bearing height h1 and the specified distance between the front face of the transmission and the front face of the hub on the fixed gear wheel for 4th gear (2 mm).
Adjustment overview
-S5- = T1 + 2 - -S3- - h1
Example:
^ h1 = 34.40 mm
^ -S3- = 0.90 mm
^ T1 = 34.42 mm
-S5- = 34.42 mm + 2 mm - 0.90 mm - 34.40 mm = 1.12 mm
Determining shim thickness S6
Information
^ The bearing pretension v2 for this bearing is always 0.10 mm.
1. Insert angular-contact ball bearing into the measuring device 9694/8 (-sides A- facing the bearing) and tighten the screw.
Inserting angular-contact ball bearing into measuring device and tightening screw
Tightening torque 10 Nm (7.5 ftlb.)
2. Measure dimension h2 between the outer bearing rings using a micrometer.
Measuring dimension h2 between the outer bearing rings using a micrometer
3. Measure the dimension at each cut-out on the measuring device 9694/8 and calculate the mean value.
Example:
^ Measurement 1: 33.97 mm
^ Measurement 2: 33.93 mm
^ Measurement 3: 33.95 mm
Bearing height h2 = 33.97 mm + 33.93 mm + 33.95 mm = 101.85 mm: 3 = 33.95 mm
4. Use a digital depth gauge to measure the depth of the bearing bore. To do this, measure the depth at three different places and calculate the mean value.
Using a digital depth gauge to measure the depth of the bearing bore
Example:
^ Measurement 1: 34.40 mm
^ Measurement 2: 34.20 mm
^ Measurement 3: 34.30 mm
Depth of bore T2 = 34.40 mm + 34.20 mm + 34.30 mm = 102.90 mm: 3 = 34.30 mm
The adjusting shim thickness -S6- is calculated as follows:
Adjustment overview
-S6- = T2 - h2 + v2
Example:
^ h2 = 33.95 mm
^ v2 = 0.10 mm
^ T2 = 34.30 mm
-S6- = 34.30 mm - 33.95 mm + 0.1 mm = 0.45 mm
Dividing the total shim thickness S1 + S2 into S1 and S2
Information
^ In order to gain as precise a setting of the backlash as possible at this point, the total shim thickness S1+S2 must be divided equally.
Example: Shim thickness S1 = 4.20 mm/2 = 2.1 mm
Example: Shim thickness S2 = 4.20 mm/2 = 2.1 mm
Information
^ Since the adjusting shims are available in thicknesses from 1.5 to 2.8 mm in 0.05-mm increments, the calculated result may have to be rounded off However, the sum of the shim thicknesses -S1- + -S2- must not be changed. To determine the thickness, measure the adjusting shims at several places with a micrometer. Also check the shims for burrs and damage.
Adjustment overview
1. Remove the differential and pull off both taper roller bearings.
2. Insert the calculated adjusting shims -S1- and -S2-.
Checking circumferential backlash
1. Read off the backlash F from the crown wheel.
Example: F = 0.15 mm
2. Insert output shaft with angular-contact ball bearing and adjusting shim -S3- into the transmission housing.
Adjustment overview
Tightening sequence for tensioning plate screws
3. Insert adjusting shim -S4- into the tensioning plate and tighten tensioning plate in the correct sequence.
Tightening torque 32 Nm (24 ftlb.)
4. Assemble differential and insert into transmission housing.
5. Fit the side transmission cover without an O-ring and pull downwards with screws. Do not tap down.
Tightening torque 26 Nm (19 ftlb.)
Information
^ Always make sure a certain amount of backlash is present when tightening the screws. The drive shaft must not jam under any circumstances.
6. Screw in special tool adjustable measuring lever VW 388 with special tool crown wheel adjusting tool VW 521/4 and set the lever length to 68 mm -a-.
Screwing measuring plunger with crown wheel adjusting tool and setting lever length
7. Insert special tool crown wheel adjusting tool VW 521/4 with special tool bush 9145 into the differential and clamp tight.
8. Turn the differential several times in both directions so that the taper roller bearings can settle.
9. Fit 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 special tool adjustable measuring lever VW 388.
10. Turn the crown wheel as far as it will go using the clamping screw on special tool crown wheel adjusting tool VW 521/4 and set the dial gauge to zero.
11. Turn the crown wheel back and read off the circumferential backlash.
12. 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.
Information
^ The total shim thickness -S1- + -S2- must not be changed.
Adjustment overview
Subsequent work
1. Assemble transmission.
2. Top up transmission oil.
3. Install transmission.
