Adjusting the Drive Set
Adjusting the drive set (transmission G 86)
Tools
Adjusting the drive set (transmission G 86)
General
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 manufacture and are checked by special inspection machines to ensure that the tooth bearing is in a good position and that there is low noise in both rotation directions.
The deviation "r" referred to the master gauge "Ro" is measured for the drive sets supplied as spare parts and is recorded on the outer circumference of the crown wheel. Every drive set (output shaft and crown wheel) must be replaced only together.
Adjustment and labelling of the drive sets (transmission G 86)
KD drive sets
1 - Identification "0937" means Oerlikon drive set with the transmission ratio of 35 : 9.
2 - Pairing number (312) of the drive set,
3 - Deviation "r" referred to the master gauge of the special inspection machine used in production. The deviation "r" is always stated in 1/100 mm.
Example: "25" means r = 0.25 mm
Ro - Length of the used master gauge of the special inspection machine.
"Ro" = 59.65 mm
R - Actual dimension between the crown wheel axis and the front side of the output shaft at the point of maximum smooth running for this one drive set.
Vo - Hypoid offset
Drive set in the series
Note In the series, the position of the output shaft is determined by the dimension Po (center of the crown wheel to the rear of the output shaft head). The labelling of the deviation "r" on the crown wheel and the pairing number are not present. Due to the deviation "r" not being given, it is necessary that, before the output shaft is replaced, to carry out an actual measurement if parts are being replaced which directly influence the installation position of the output shaft.
X - These details are not required in the series.
Po,- Adjustment dimension for the series.
Adjustment overview (transmission G 86)
When carrying out assembly work on the final drive, readjustment of the output shaft and crown wheel or drive set is necessary only if parts are being replaced which directly influence the adjustment of the final drive. In order to avoid unnecessary adjustment work, pay attention to the table:
Appropriate sequence for readjusting the drive set (transmission G 86)
If the output 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 disc thickness "Stot" (S1 plus S2) for the correct preload of the tapered roller bearings/differentials.
2. Determine the total disc thickness "Stot" (S3 plus S4) for the correct preload of the tapered roller bearings/output shaft.
3. Divide up the total disc thickness "Stot" in S3 and S4 so that the measurement from the crown wheel center to the front of the drive pinion corresponds to the installation dimension "R" measured during production.
4. Divide up the total disc thickness "Stot" in S1 and S2 so that the stipulated circumferential backlash is present between the crown wheel and output shaft.
The aim of the adjustment is to again achieve the position of maximum smooth running which was determined in production on the testing machine.
The greatest possible care and cleanliness during all assembly work and measuring procedures are essential requirements for a perfect result.
Determining the installation position of the output shaft (actual measurement)
This work must be carried out only if the deviation "Y" is not given on the crown wheel and if parts are to be replaced which directly influence the output shaft position. These are: Both tapered roller bearings for the drive pinion and the transmission housing.
Remove the differential.
Complete the universal measuring mandrel, as described. Insert it into the transmission housing and measure the difference to "Ro" (maximum deflection/reversing point). The measured value corresponds to the deviation "r". Note the value.
After replacing the parts, adjust the output shaft as described. When doing so, use the deviation Ur" determined when measuring the adjusting shim "S3".
Adjusting the output shaft (transmission G 86)
Readjustment of the output shaft in accordance with the instructions below is necessary only if the drive set is replaced. If other parts which also influence the output shaft position are changed, make the adjustment via the previously determined installation position.
1. Total disc thickness Stot. (S3 + S4).
Preload of the tapered roller bearings/output shaft
- Install the outer races for the tapered roller bearings without adjusting shims in the transmission housing or in the transmission case cover. Always use rubber washer and pressure plate for measuring the disc thickness and for measuring the S4 disc.
Note Pressure plates of various thicknesses can be installed.
- Fit the inner races for the tapered roller bearings. 35, Disassembling and assembling the output shaft). Secure the lower tapered roller bearing (arrow).
- Place the transmission housing on the workbench.
- Put the output shaft into the transmission housing.
- Put on the transmission case cover and tighten the screws with 25 Nm (18 ft. lbs.).
- Turn the gears so that the transmission case housing faces downwards.
- Using the special tool VW 296, press on the output shaft head until the tapered roller bearing outer race fits closely in the transmission case cover.
- Turn the output shaft manually until the tapered roller bearing settles.
- Assemble the measuring tool and set the dial gauge with 1 mm preload to "0".
- Turn the transmission through 180° so that the transmission case cover faces upwards.
- Turn the output shaft manually so that the tapered roller bearing settles.
- Read off the measurement result on the dial gauge (e.g. 1.45 mm).
- Measure the total disc thickness "Stot." (S3+S4)
Stot.= Measurement result + pressing
Pressing (constant value) 0.15 mm
Measurement result + 1.45 mm
Stot. 1.60 mm
2. Checking the preload of the tapered roller bearings for the output shaft.
- Install the measured total disc thickness (example 1.60 mm) behind the tapered roller bearing outer race of the transmission case cover (S4 side).
- Put on the transmission case cover and tighten the fastening screws with 25 Nm (19 ft. lbs.).
- Turn the output shaft a few times so that the tapered roller bearings settle.
Note Screw the screw into the shaft head in order to turn the output shaft.
- Fit the measuring tools.
- Set the dial gauge (3 mm measurement range) with 1 mm preload to "0".
- Undo the screws of the transmission case cover and read off the dial gauge.
Note The dial gauge may now display a value of 0.08 mm to 0.15 mm with correctly selected adjusting shims.
3. Determining the dimension "e"
- Allow the measured total disc thickness (in the example 1.60 mm) into the tapered roller bearing outer race in the transmission case cover (S4 side).
- Refit the transmission case cover.
- Turn the output shaft a few times so that the tapered roller bearings settle.
- Adjust the setting collar of the special tool VW 385/1 to the dimension "a" = 35 mm."
- Adjust the movable setting collar to the dimension "b" = 65 mm.
- Complete the universal measuring mandrel as shown in the illustration.
- Set the master gauge, special too[ 385/30, to the dimension Ro = 59.65 mm and place on the measuring mandrel. Set the dial gauge (3 mm measurement range) with 1 mm preload to "0".
- Place the end plate, special too[ VW 385/33, onto the output shaft head.
- Remove the master gauge and insert the measuring mandrel with the dial gauge downwards into the housing.
- Put on the cover for the final drive and secure it with 4 screws.
- Pull out the 2nd centering disc via the movable setting collar far enough so that the measuring mandrel can still just be turned manually.
- Measure dimension "e".
Turn the measuring mandrel until the dial gauge tip touches the end plate on the output shaft head and displays the maximum deflection (reversing point). The measured value is the dimension "e" (black number range).
Example 0.46 mm
- Arrangement of the measuring tools for determining dimension "e".
4. Determining the thickness of the adjusting shim "S3"
S3 = e + r
e = Measured value (maximum deflection)
r = Deviation (given in 1/100 mm on the crown wheel or is determined in the actual measurement)
Example
Discs of 0.55 mm ... 1.05 mm thickness are available (0.05 mm increments). Different tolerances allow the required disc thickness to be measured exactly.
5. Determining the thickness of the adjusting shim "S4"
S4 = Stot. - S3
Example
Note Pressure plates of 14.8 mm or 15.3 mm can be installed.
Discs of 0.45 mm ... 1.49 mm thickness are available (0.04 mm increments). Different tolerances allow the required disc thickness to be measured exactly.
6. Performing a check measurement (checking dimension "r").
- Install the output shaft with the measured adjusting shims S3 and S4 and turn several times in both directions.
- Insert a universal measuring mandrel (special tool) and carry out a check measurement.
- If the selected adjusting shims are the correct ones, the dial gauge must display the value of the written deviation "r" (in the example 0.18 mm) with a tolerance of ± 0.04 mm when read off counterclockwise (red number range).
Determining "S4" again (transmission G 86)
Note If only the transmission case cover is replaced, only the adjusting shim "S4" must be measured again.
1. Clean the housing mating face.
2. Place the output shaft in the transmission case cover and turn so that the tapered roller bearing settles.
3. Assemble the measuring tools.
4. Set the dial gauge (3 mm measuring range) to "0" with 1 mm preload.
5. Carefully remove the special tool VW 387 with the dial gauge.
Note Handle the holder and dial gauge with care so that they do not become misadjusted.
6. Remove the output shaft and outer race of the tapered roller bearing with the pressure plate, adjusting shim and rubber washer, and install them in the new transmission case cover.
7. Place the dial gauge on the new transmission case cover with the special tool VW 387 as shown in Figure 165 - 96 and read off the value on the dial gauge (in the example 0.88 mm).
Example
Note If the read-off value on the dial gauge is greater than 1.00 mm, the thickness of the adjusting shim "S4" must be reduced by the value X.
8. Fit the transmission case cover and check the preload of the tapered roller bearings for the output shaft.
Adjusting the crown wheel (transmission G 86)
Determining the total disc thickness "Stot." (S1 +S2).
Readjustment of the crown wheel is necessary if the transmission housing, the cover for the final drive, the tapered roller bearings for the differential, (the differential housing) or the drive set are replaced.
Note The output shaft must be removed in order to determine the preload of the tapered roller bearings on the differential.
1. Remove the sealing rings and tapered roller bearing outer races for the differential and take out the adjusting shims.
2. Install the tapered roller bearing outer races without adjusting shims.
3. Put the differential without the speedometer-drive gear into the housing, put on the cover and tighten all screws with the stipulated tightening torque.
4. Fit the special tools 521/4 and 521/12.
5. Place the special tool VW 385/17 onto the collar of the differential.
6. Secure the special tool VW 387 with the dial gauge and extension to the housing, and set to "0" with 1 mm preload.
7. Move the differential up and down. Read off and note the play at the dial gauge.
Example: 1.42 mm
Note When measuring the play, do not turn the differential, otherwise the measurement result will be corrupted.
8. Calculate "Stot.".
"Stot." = measurement result + pressing.
Example
9. Install the determined total disc thickness "Stot." behind the tapered roller bearing outer race in the transmission housing.
10. Measure the friction torque with a commercially available torque gauge (0 ... 600 Ncm (0 ... 53 inch lbs.)). It must be 250 ... 350 Ncm (22 ... 31 inch lbs.) in the case of new tapered roller bearings and it must be 30 ... 60 Ncm (2.6 ... 5.3 inch lbs.) in the case of run-in tapered roller bearings (bearings filled with gear oil).
Note When readjusting the drive set, also adjust the output shaft and perform a check.
Adjusting the circumferential backlash (transmission G 86)
The circumferential backlash must be 0.12 mm... 0.22 mm.
1. Install the output shaft with the adjusting shims "S3" and "S4".
2. Insert the differential, fit the cover and tighten all fastening screws with the stipulated tightening torque.
3. Screw the special tool VW 388 to the special tool VW 521/4 and adjust the lever length to 72 mm with the gauge plunger.
4. Insert the adjustment device with the special tool VW 521/12 into the differential and clamp it securely.
5. Turn the differential several times in both directions so that the tapered roller bearings settle.
6. Fit the dial gauge holder with the dial gauge so that a right angle is produced between the dial gauge axis and the lever.
7. Carefully turn the crown wheel as far as it will go via the clamping screw of the adjustment device and set the dial gauge to zero. Next, turn the crown wheel back and read off the circumferential backlash. Note the value.
Note If the friction coefficient of the output shaft is too low, the special tool 3177 must be fitted so that an exact circumferential backlash can be measured. The differential can then only be inserted in such a way that the aperture of the bevel gears faces the output shaft.
8. Repeat the measuring procedure another three times after continuing to turn the crown wheel through 90' in each case. Add up the measured values and calculate the average circumferential backlash. With the assembled special tool 3177, install the differential offset by 180° and repeat the measuring procedure.
Note It the individual measured values deviate from each other by more than 0.06 mm during this measurement, installation of the crown wheel or the drive set itself is not in order. Inspect the assembly work and replace the drive set if necessary.
9. Determine the average circumferential backlash.
Example
Average circumferential backlash:
3.36 : 4 0.84 mm
10. Determining the disc thickness "S2" (with respect to the crown wheel)
S2 = Stot.
- Average circumferential backlash
+ Take-off (constant value)
Take-off = 0.15 mm
Example
Note Discs of 0.45 mm ... 1.00 mm thickness are available (0.05 mm increments). Different tolerances allow the required disc thickness to be measured exactly.
11. Determining the disc thickness "S1" (crown wheel side)
S1 = Stot. - S2
Example
Note Discs of 0.45 mm... 1.00 mm thickness are available (0.05 mm increments). Different tolerances allow the required disc thickness to be measured exactly.
12. Install determined adjusting shims "S1" on the crown wheel side and "S2" opposite the crown wheel.
13. Carry out a check measurement. When doing so, measure the circumferential backlash four times around the circumference. It must be 0.12 ... 0.22 mm.
Note The individual measurement results may deviate from each other by maximum 0.05 mm.