Screw bolt in drive pinion. Apply torque meter and read friction torque.
For new bearings it should be 200 to 400 Ncm or 30 to 60 Ncm for used bearings.
Lubricate bearings with hypoid gear lube.
Measure thickness of shims at many different points with a micrometer. Also check shims for burrs or damage. Only install shims in perfect condition.
Adjusting Ring Gear Note
The ring gear has to be adjusted, if transmission case, final drive cover, tapered roller bearings for differential and/or pinion/ring gear set are replaced (also refer to "necessary adjustments").
Determining Total Shim
(For determination of pre-load for tapered roller bearings on differential.)
1. Remove drive pinion.
2. Remove seals for shaft flanges.
3. Remove outer races of tapered roller bearings for differential. Take out shims.
4. Drive in tapered roller bearing outer races without shims against stop.
5. Place differential in case. Installed position: ring gear facing cover.
6. Install cover and tighten bolts crosswise to 25 Nm (18 ft lb).
7. Clamp transmission in assembly stand with cover facing up.
A — Dial gauge extension approx. 30 mm
8. Place gauge plate VW 385/17 on collar of differential.
9. Mount universal dial gauge holder VW 387 with dial gauge and extension on case and set dial gauge to zero with 1 mm pre-load.
10. Move differential up and down, read play on dial gauge and note value (e. g. 1.42 mm).
11. Install shims with determined total shim thickness "Stot" (1.92 mm in example) behind tapered roller bearing outer race in cover (S2 side). Lubricate both tapered roller bearings with hypoid oil.
12. Mount cover again.
13. Guide adjusting device VW 521/4 with sleeve VW 521/8 into neck of differential and clamp.
14. Place 0 to 600 Ncm torque meter on adjusting device and turn slowly and uniformly. The friction torque of new tapered roller bearings must be at least 250 Ncm.
A — Dial gauge extension approx. 30 mm Note
Do not turn differential while measuring play, since this would cause wrong results.
"Stot" = measured value + pre-load
Friction torque of used tapered roller bearings need not be measured.
When adjusting the pinion/ring gear set, now check the drive pinion adjustment.
Measured value (example) Pre-load (constant value)
Determining Mean Backlash
Requirement: drive pinion adjusted and installed with S3 and S4.
Turn differential several times to pre-load and settle tapered roller bearings.
1. Place adjustable lever VW 388 on adjusting device VW 521/4. Lever length via large hexagon surface 79 mm to upper edge of ball.
2. Apply universal dial gauge holder with dial gauge and extension so that there is a right angle between the dial gauge axis and lever.
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