Pinion, Adjusting

Pinion Adjusting
Adjustment of the pinion as described here is only necessary when the gear set, pinion or transmission housing tapered roller bearings have been replaced.

Determining total shim thickness S_total (S3 + S4)
(Adjusting preload of pinion tapered roller bearings)

- Install outer races of tapered roller bearings, without shims, in transmission and cover.

Always install shim (rubber) and pressure plate to measure shim thickness and to determine the S4 shim.

Pressure plates with different thicknesses (14.8 to 15.3mm) can be installed.

- Press on large tapered roller bearing inner race. Input Shaft





- Secure lower taper roller bearing (arrow).
- Press on small taper roller bearing inner race.
- Place pinion in transmission housing.
- Install transmission cover and tighten to correct torque.
- Turn assembly so that cover is facing downward.





- Turn pinion shaft by hand until tapered roller bearing has settled into position.





- Set up measuring fixture and turn dial indicator to zero, with 1mm preload.
The extension must be positioned on the ground face of the pinion.
- turn transmission 180° so that cover is at top.
- Turn pinion by hand 8 turns.

CAUTION
Before taking the measurement, turn the pinion so that the tapered roller bearing can settle. Otherwise the measurement will be incorrect.





- Note reading on dial indicator.





Example:

Checking preload of tapered roller bearing for pinion:
- Using calculated total thickness (S_total, 1.60 mm in example above) select shim from table and install behind tapered roller bearing outer race in transmission cover (S4 side).
- Install transmission cover and tighten bolts to correct torque.
- Install M10x20 bolt on pinion head and turn pinion at least 8 turns so that tapered roller bearings can settle.
- Remove bolt.





- Set up measuring tools and secure with bolt (arrow) to transmission housing.
- Set dial indicator (3mm measuring range) to zero with 1mm preload.
- Loosen transmission cover bolts and turn pinion shaft several times.
If the correct shim has been selected the dial indicator will indicate a value of 0.05 mm to 0.15 mm.

Determining dimension "e"
- Leave previously calculated shim thickness (1.60 mm in example) in place behind the tapered roller bearing outer race in transmission cover (S4 end).
- Install transmission cover again.
- Install M10x20 bolt on pinion head and turn pinion at least 8 turns so that tapered roller bearings can settle.
- remove bolt.





- Adjust setting ring of universal gauge VW 385/1 to dimension a =35 mm.
- Adjust sliding ring to dimension b = 75mm.





- Set up universal measuring bar as illustrated.
- Select dial gauge extension -A- from table:





- Adjust master gauge VW 385/30 to Ro according to ring gear diameter and place on measuring bar.

^ Ring gear diameter 180mm: Ro = 59.65mm
^ Ring gear diameter 170mm: Ro = 54.95mm

- Set dial indicator (3mm measuring range) to zero with 1mm preload.





- Place end plate on face of pinion.





- Remove master gauge and insert measuring bar in housing.

NOTE:
For Ro=54.95 mm, a 6.5 mm extension must be used instead of the extension VW 385/15 Shown.

- Install final drive cover and tighten bolts.
- Use sliding setting ring to pull 2nd centering disc out far enough so mandrel can still be turned by hand.





- Measure dimension "e"
- Turn measuring bar until dial indicator extension touches end plate at pinion head and indicates maximum deflection (reversal point).
Measurement = dimension "e"(black gauge range)
Example: 0.46mm

Determining shim "S3" thickness
S3 = e - r
e - Gauge reading (Max. deflection)
r - Deviation (Marked on ring gear in units of 1/100 mm or determined by actual measurement.

Example:





Different tolerances make it possible to select the exact thickness of shims required.

Determining shim "S4" thickness
S4 = S_total-S3

Example





Checking measurements - checking dimension "R"
- Install pinion with measured shims S3 and S3 and turn several times in both direction.





If shims have been selected correctly, the dial indicator, reading counterclockwise (red gauge range), must indicate inscribed value of deviation "r" within tolerance of +/- 0.04 mm.