Pinion Shaft, Adjusting
Pinion Shaft, Adjusting
Readjusting pinion shaft is required if
^ Transmission housing
^ Drive pinion tapered roller bearing
or
^ Gear set are replaced.
When replacing bushings for drive pinion, parking lock gear, output gear, spacer tube or cover for drive pinion, need only redetermine shim "84"
Adjustment overview Overview
Adjusting beveled gear tapered roller bearing preload
- Press on large tapered roller bearing inner race with bushing for drive pinion.
- Pull tapered roller bearing outer race with shim "S3" (1.50 mm thick) into transmission housing.
- Press tapered roller bearing outer race into drive pinion cover.
- Insert drive pinion in transmission housing.
A - Assembly sleeve 3187
- Press drive pinion against tapered roller bearing outer race using press lever VW 296 and hold in this position.
- Assemble parking lock gear, heated output gear and shim "S4" (2.40 mm thick) (arrow) (use 2 x 1.20 mm thick shims).
- Slide on spacer tube.
- Install drive pinion cover.
- Insert tapered roller bearing inner race and screw nut (arrow) onto drive pinion.
- Tighten the four bolts for drive pinion cover to 25 Nm (18 ft. lbs.).
- Set parking lock.
- Preload hex nut to 340 Nm (251 ft. lbs.).
A - Torque wrench
B - Wrench socket (41 mm AF)
- Loosen hex nut and tighten to 250 Nm (184 ft. lbs.).
- Mount D.T.I. and "0" with 1 mm preload.
- Move drive pinion up and down and read off clearance indicated on D.T.I. (example: 0.95 mm).
When performing measurements, do not turn drive pinion as the bearings will settle and give a false measurement.
The specified bearing preload is achieved if: the reading ,0.95 mm (0 037 inch), the preload of the bearings 0.15 mm (0.005 inch) and the amount for compression 0.10 mm (0.010 inch) are deducted from the 2 x 1.2 mm (0.08x 0.05 inch) thick shims.
Example:
- Remove output gear. Determine size of shim "S4" on basis of table (shown in Input Gear) and install on drive pinion.
- Reinstall output gear, tighten hex nut to 250 Nm (184 ft. lbs.) and secure with punch.
Friction torque, checking
^ Input gear and differential removed.
Friction torque can only be checked if tapered roller bearings have been replaced.
If the bearings have not been replaced, friction torque is not checked. The drive pinion should then be adjusted as described.
A - Torque gauge, commercially available, 0...600 Ncm
B - Wrench socket (41 mm AF)
Friction torque of new tapered roller bearings must be 80...120 Ncm (7-11 inch lbs.).
- Oil bearing beforehand with gear oil.
Determining shim S3 and S4 thickness
- Set measuring bar VW 385/1 setting ring to dimension a = 70 mm.
- Arrange measuring bar as illustrated.
A - Measuring gauge extension VW 385/16 = 12.3 mm.
- Set measuring bar VW 385/30 to Ro = 59.2 mm.
- Preload measuring gauge to 1 mm and zero.
- Place end of measuring plate on face of pinion shaft.
- Insert measuring bar -A-.
- Install final drive cover and tighten 4 bolts.
- Using sliding setting ring to pull 2nd centering disc outward until bar can just be turned by hand.
- Measure dimension "e." Turn bar until tip of dial indicator makes contact with end measuring plate and indicates max. deflection (return point). The measurement achieved is dimension "e" (less than 1 mm in red figure range, more than 1 mm in black figure range). Example: 0.32 mm (red figure range)
- Remove measuring bar.
Check again that the dial indicator returns to "0" with master gauge VW 385/30 at 1 mm preload, otherwise repeat measurement.
Add dimension "e" if measurement is in red figure range. Subtract dimension "e" if measurement is in black figure range.
Determining shim "S3" thickness
- Add measured value "e" to already inserted shim "S3" thickness and subtract dimension "r" (ring gear in 1/100 mm).
Example:
Determining shim "S4" thickness
- Add measured value "e" to already inserted shim "S4" thickness and subtract dimension "r" (ring gear in 1/100 mm).
Example:
If a thicker "S3" shim is required then a thicker "S4" (same difference) must be installed.
If a thinner "S3" shim is required then a thinner "S4" (same difference) must be installed.
- Determine shims according to table.
Table of shims for "S3"
Table of shims for "S4"
(1) Different tolerances enable the required "S4" shim thickness to be measured precisely, use 2 shims if necessary.
Dimension "R," measurement check
- Install pinion shaft with measured shims S3 and S4 and turn in both direction several times.
Insert measuring bar and measure dimension "R"
If the correct shims have been selected the D.T.I. must now indicate the mark dimension "r" (reading counter-clockwise on red scale) within a tolerance of ± 0.04 mm.