Disassembly
Remove the speedometer drive gear and drive clutch using a puller with jaws and a mandrel.
Press the inner races of the tapered roller bearings from the differential box by inserting the hooks of the puller into the T-shaped cutouts of the differential box and using the VW 295a mandrel.
Remove the eight hex bolts securing the final drive gear to the differential case.
Install the final drive gear on the two stops and press the differential box off the gear.
Remove retaining ring from pinion shaft and press pin out.
Remove satellites and side gears.
Remove the retaining clip.
Check the condition of parts and replace damaged parts.
Assembly
Install the thrust clip on the differential box.
Install side gears with threaded washers.
Install the output shafts in the holes of the differential and tighten them with bolts.
Install the satellites, turning them at an angle of 180°C, then by turning the output shafts bring the satellites into their seats.
Finally adjust the position of the thrust holder and satellites.
Install the pinion axle and circlips, using the dowel pins to ensure proper seating.
Install the driven gear of the final drive heated to 100°C on two stops, slide the differential box onto the gear and tighten it with two bolts. After the driven gear and differential box have cooled down, install the remaining bolts and tighten them to a torque of 5.50 kgf·m.
Press the inner ring of the tapered roller bearing onto the differential box using a VW 519 guide bush with a diameter of 50 mm, while the ring must be preheated to 100°C.
Press on the second tapered roller bearing inner race in the same way.
Install the speedometer drive gear and press on the drive bushing, ensuring the seating depth «X» (see photo) bushings by selection of adjusting rings with a thickness of 1.4 to 1.5 mm. Pressing depth «X» bushings should be 1.4 mm.
Calculation of the thickness of the adjusting rings of the rear bearings of the primary and secondary shafts
Note. This operation must be carried out very carefully, since the thickness of the shim and gasket affect the position of the final drive gear. The measurements must be made with the outer races of the bearings pressed in as far as they will go.
To select the thickness of the adjusting rings of bearings, it is necessary to determine the following dimensions (see picture):
- a - protrusion of the input shaft ball bearing from the gearbox housing:
- b - protrusion of the tapered roller bearing of the secondary shaft from the gearbox housing;
- c - drowning of the supporting surface of the rear bearing of the secondary shaft in the rear cover of the gearbox;
- d - drowning of the bearing surface of the rear bearing of the input shaft in the rear cover of the gearbox;
- s is the thickness of the adjusting ring of the rear bearing of the secondary shaft;
- v is the thickness of the adjusting ring of the input shaft rear bearing;
- e is the thickness of the gasket.
Determine dimensions with a depth gauge «A», «b», «With» and «d».
The input shaft bearing of some gearboxes is combined (rollerball). In this case, a sealing gasket with a thickness of 0.40 mm is installed, and the adjustment of the axial movement of the bearings is carried out by selecting the thickness of the adjusting rings installed under the bearings of the primary and secondary shafts.
On other gearboxes, the necessary protrusion of the input shaft rear bearing is provided by installing a sealing gasket with a thickness of 0.30 or 0.40 mm.
The rear bearings of the input and output shafts are installed with a preload of 0.10 mm, provided by compressing the gasket. On a gearbox with a ball bearing of the input shaft, the thickness of the gasket is selected based on the size «A». If size «A» is 0.20-0.26 mm, a gasket with a thickness of 0.30 mm should be installed. If size «A» is in the range of 0.27-0.42 mm, it is necessary to install a gasket with a thickness of 0.40 mm. On gearboxes with combined input shaft bearings, the gasket thickness is constant and equal to 0.40 mm.
Calculate the thickness of the adjusting rings using the formulas:
s=c-b+0,3,
v=d-a+0.3 (0,4).
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