Inspect the speedometer drive gear. If the differential bearing located above the gear is to be replaced, then it is necessary to remove the speedometer drive gear by cutting it with a chisel.
Special tools are required to replace the gears or differential case, so leave this work to a VAG representative. The internal bearings and differential gears must be adjusted with shims after replacement, and special measuring equipment is required. It may be more economical to replace the entire differential.
It is possible to replace the thrust bearings of the differential, but after that it is necessary to adjust their preload.
Replacing bearings and adjusting preload
1. Remove the inner races of the tapered bearings together with the rollers (pic. I:52).
ATTENTION. Before removing the bearing removed from the driven gear of the final drive, remove the speedometer drive gear by cutting it with a chisel (pic. I:53).
2. Press on the new speedometer drive gear and new bearings using a metal mandrel. The bearing inner rings must be heated to approximately 100°C before installation.
3. Knock out the outer races of the bearings from the gearbox housing and clutch housing with a metal drift and remove the 1 mm thick shims.
4. Install the same gasket (1 mm) and press the new bearing outer race into the gearbox housing with new seals.
5. Press the second bearing outer race into the clutch housing seat.
6. Install the differential in the reverse order of removal, tightening the crankcase mounting bolts to the required torque.
7. Install a 3 mm plate into the clutch housing on the outer bearing of the differential (fixture VAG No. 385/17).
b. Install a dial indicator on the clutch housing, and install its probe on a three-millimeter plate. Set the indicator scale to zero.
9. Move differential within bearing play. Note the amount of movement on the arrow indicator.
10. Install a shim to provide the correct bearing preload. Determine the thickness of the gasket as follows: to the measured gap (bearing end play) add a fixed number (typically 0.30 mm - refer to section "Technical data").
11. Remove the clutch housing, press out the outer race of the bearing and insert a gasket of the required thickness.
12. Install the clip in the clutch housing and check the size again.
13. Assemble the gearbox as described above.
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