Adjusting Front Drive Set
Adjusting
- If it is necessary to adjust drive pinion and ring gear, following this sequence will ensure an efficient working procedure:
1. Determine total shim thickness "Stot" (S1 plus S2) for specified preload of tapered-roller bearing/differential.
2. Determine shim thickness "S3".
3. Determine bearing pressure "S4".
4. Split total shim thickness "Stot" into S1 and S2 so that there is the specified circumferential backlash between ring gear and drive pinion.
- The purpose of this adjustment is to once again achieve the position of smoothest running which was obtained on test equipment in the production line.
- A correct result requires the greatest possible degree of cleanliness during all assembly work and measuring procedures.
- It is only necessary to adjust the drive pinion and ring gear or drive set when working on the final drive assembly if parts have been replaced which have direct influence on the adjustment. Refer to the table in order to avoid unnecessary adjusting procedures
1 - Spacer S1
2 - Spacer 52
3 - Shim S3
4 - Shim S4
E - Adjustment dimension
- Correct results require cleanliness and care for all assembly operations and measuring procedures.
Ro = Design dimension
r = Deviation r
1 = Setting value (Ro + r) e.g. 59.22
2 = Backlash, e.g. F 0.16
3 = Matching number
- The setting of drive pinion, ring gear and bearing pressure of both tapered roller bearings on the drive pinion are determining factors for the service life and smooth running of the front-axle final drive. Drive pinion and ring gear are therefore already matched during production, which are checked for good surface appearance and low noise factor in both directions of rotation on special test equipment. The position where smoothest running is achieved is determined by shifting the drive pinion axially, whereby the ring gear is kept within the tolerance of specified backlash. Deviation "r" from the specified design dimension "Ro" is determined, added to design dimension "RQ" and embossed on the ring gear as setting value "E".
Adjusting Drive Pinion (shim S3)
1 = Setting value "E" (from ring gear)
NOTE: Use shims which are 2.0 mm thick as shim thickness "S3" between front outer bearing race and housing as a starting point for the adjustment of the drive-pinion bearing.
- Heat front drive-pinion bearing up to approx. 120°C (248 °F) and press onto the drive pinion in the correct position.
A = Outer bearing race
B = Outer bearing race
C = Pressing tool VW 511
D = Pressing tool 9502
E = Threaded spindle VW 517
F = Shim "S3"
- Insert drive pinion with spacer sleeve, heat rear drive-pinion bearing up to approx. 120°C (248°F) and mount onto the drive pinion without shim "S4".
- Tighten the lock nuts of drive pinion carefully up to a maximum of 100 Nm (74 ft lb) using Special Tools 9503 and 9505 until you reach a drag moment of 270-350 Ncm.
NOTE: Check the moment of drag from time to time while tightening the nuts.
"a" = ca. 55 mm
- Set the adjusting ring of measuring mandrel VW 385/1 to dimension "a".
- Assemble measuring mandrel with centering disk VW 385/4, plunger VW 385/14 and dial gauge extension VW 385/15.
- Set measuring mandrel with gauge 385/30 to selling value (59.22 mm in the example). Set dial gauge (3 mm measuring range) to zero with 1 mm preload.
- Place final dimension plate 9281 onto the drive-pinion head and insert measuring mandrel into transmission case. Dial-gauge extension located in the area of the final dimension plate.
- Fit side transmission cover without 0-ring and fasten cross-wise with 4 nuts.
NOTE: Do not use a hammer when fitting the side transmission cover (the magnet-fitted final dimension plate may fall). Settle the cover in its installation position by tightening the nuts uniformly.
- Pull second centering disk with spindle far enough outwards that it is just still possible to turn the measuring mandrel by hand.
- Turn measuring mandrel carefully until the dial-gauge extension is vertical to the facing surface of the drive-pinion head. At this point, the pointer of the dial gauge reaches maximum deflection (reversing point), at which point the dial gauge should be read.
NOTE: If the measured value deviates from the setting value "E" clockwise (59.22 mm in the example) then the dimension is less than 59.22 mm; that means that the value deviating from zero must be subtracted from dimension 59.22.
Example
The small pointer on the dial gauge is pointing between 1 and 2, the large pointer indicates 0.15 mm.
Dial-gauge setting 59.22 mm
Measured value - 0.15 mm
___________
Value towards drive 59.07 mm
pinions facing
Setting value "E" (e.g.) 59.22 mm
Value towards drive - 59.07 mm
pinion facing
_____________
Deviation 0.15 mm
- The drive pinion must therefore be shifted a further 0.15 mm away from the middle of the ring gear.
- This is achieved by using a shim "S3" which is 0.15 mm thinner. At the same time, round up or down to the nearest 0.05 mm.
- If the measured value deviates from setting value "E" counterclockwise (59.22 mm in the example) then the dimension is greater than 59.22 mm; that means that the value deviating from 0 must be added to dimension 59.22.
Example
The small pointer of the dial gauge indicates between 1 and 0, the large pointer indicates 0.08 mm.
Dial-gauge setting 59.22 mm
Measured value + 0.08 mm
_____________
Value towards drive 59.30 mm
pinion facing
Value towards drive 59.30 mm
pinion facing
Setting dimension "E"(e.g.) - 59.22 mm
_____________
Deviation 0.08 mm
- The drive pinion must therefore be shifted nearer to the middle of the ring gear by a further 0.08 mm.
- This is achieved by using shim "S3" which is thicker by 0.08 mm.
- At the same time, round up or down to the nearest 0.05 mm.
- After altering shim "S3" check setting value "E" once again. A deviation of ± 0.03 mm is permitted.
Adjusting Ring Gear (S tot)
NOTE: The ring gear must be readjusted TO determine "S tot" (S1 = S2) if transmission case, side transmission cover, tapered roller bearing for differential, differential housing or drive set have been replaced. The drive pinion must be removed to determine the preload of tapered roller bearing on the differential.
- Make sure that the outer bearing races of the tapered roller bearing are firmly secured in transmission case or side transmission cover.
- Fit a spacer, 2 mm thick, on ring-gear side and opposite side of differential to be used.
- Insert differential into transmission case and crank several times.
- Install side transmission cover without seal and tighten all hexagon nuts to 23 Nm (17 ft lb).
- Place final dimension plate VW 385/17 on the collar of the differential.
A = Dial-gauge extension
(approx. 3O-40 mm long)
- Fasten universal dial-gauge holder VW 387 with dial gauge and extension to the housing and set to zero with 2 mm preload.
- Move differential up and down. Read backlash off dial gauge and record.
NOTE: Do not turn differential while measuring backlash as this will falsify the measuring result.
- Calculate "S tot."
^ "S tot." = Thickness of shim provided + measured value + Pressure of tapered roller bearing
Example
Thickness of shim provided 4.00 mm
Measured value 0.80 mm
Pressure (constant value) 0.30 mm
_________
"S tot" 5.10 mm
- Remove differential, pull off both tapered roller bearings and split the calculated thickness of shims "S tot" as follows.
- Select a spacer S1 which is 0.70 mm thinner and S2 which is 0.70 mm thicker as a starting point for subsequent adjustment of the backlash.
Example
Total thickness of spacers
S1 + S2 = 5.10 mm
Thickness of spacer S1
5.10 mm divide by 2 = 2,55 mm
- 0,70 mm
_____________
S1 = 1,85 mm
Thickness of spacer S2
5.10 mm divide by 2 = 2,55 mm
+ 0,70 mm
_____________
S2 = 3,25 mm
NOTE: Spacers are available in thicknesses from 1.6-3.1 mm in increments of 0.10 mm. A 0.25 mm thick shim is provided to enable the spacer thicknesses to be graded into increments of 0.05 mm. The calculated spacer thicknesses must therefore be rounded up or down to feasible values in such a way that the total shim thickness S1 and S2 is not altered. Measure shims with a micrometer in several places. Permitted deviation 0.02 mm. Also check shims for burrs and damage.
Adjusting Bearing Load on Pinion (S4)
NOTE: The setting value "E" must be within the tolerance of ±0.03 mm in order to determine the bearing pressure.
- Fit drive pinion with 2.5 mm thick shim "S4", heat rear drive-pinion bearing up to approx. 120 °C (248 °F) and install.
- Tighten lock nut with 230 Nm (169.5 ft lb) using Special Tools 9503 and 9505.
- Fasten universal dial-gauge holder VW 387 to the housing and set dial gauge to 0 with 2 mm preload.
- Move drive pinion in axial direction and measure backlash on dial gauge, noting the value.
NOTE: Do not turn drive pinion while measuring backlash as this will falsify the measured result.
- Calculate bearing pressure.
Example
Inserted shims 2.50 mm
Measured backlash - 0.95 mm
Axial preload - 0.15 mm
(constant value)
_____________
Shim "S4" 1.40 mm
- Remove drive pinion and install shim "S4" of the calculated value.
- Tighten lock nut to 230 Nm (169.5 ft lb)
- Check setting value "E" and moment of drag (270-350 Ncm) several times.
Adjusting Circumferential Backlash
NOTE: The backlash to be set is indicated on the ring gear.
- Install drive pinion using shims "S3" and "S4" determined while adjusting the drive pinion.
NOTE: The collar nut for the drive pinion must always be tightened to 230 Nm (169.5 ft lb) before measurement.
- Fit differential with tapered roller bearing and calculated spacers (S1 + S2) into housing.
- Fit side transmission cover and tighten all hexagon nuts to 23 Nm (17 ft lb).
NOTE: Always bear in mind that there is a certain amount of backlash when tightening the nuts. Under no circumstances may the drive pinion seize.
Dimension "a" = approx. 75 mm
- Attach measuring lever VW 388 to adjusting device VW 521/4 and set lever length to 75 mm with plunger over the large hexagon surface (refer to dimension "a" in the figure).
- Insert adjusting device into differential with clamping sleeve (Special Tool 9145) and clamp firmly.
- Crank differential in both directions several times to settle the tapered roller bearing.
- Assemble universal dial-gauge holder with flat extension in such a way as to produce a right-angle between dial-gauge axis and lever.
- Turn ring gear carefully with the hexagon of the adjusting device as far as the stop, and set dial gauge to zero. Turn back ring gear and read off circumferential backlash. Make a note of the value.
NOTE: Always hold the drive pinion with Special Tools 9505 and 9506 when measuring.
- Repeat measuring procedure another three times, turning the ring gear a further 90° in each case. The measured values may not deviate from one another by more than 0.05 mm.
NOTE: The backlash to be set is given on the ring gear. The actual value may be less than this value by 0.05 mm. Under no circumstances may the backlash be greater than this value.
- If it is not possible to achieve the prescribed backlash, then the spacers (S1 + S2) must be replaced again. At the same time, the total thickness of shim (Stot) must not be altered.