Hypoid bevel gear differential and multidisc lock - Remove and refit the drive pinion



Uncouple the tractor between the intermediate housing and the centre housing. Remove the creeper unit (if fitted). Free the ratchet of the Park Lock transmission lock (if fitted). Locate the position of and take out the sleeve linking the drive pinion and the lower shaft. Remove the hydraulic pump bearing / drive pinion assembly.

Removing the drive pinion
Disconnect control pin (25) of the handbrake mechanism. Remove bolt (1). Take off pipe (57) located at the taper end of the drive pinion.


Release and immobilise nut (18) using wrench, ref. 3378118M1. Place special socket, ref. 3378119M1, on the end of the drive pinion and turn clockwise.


Remove bearing cone (1), shims (3) and thrust washer (4). Take out two diametrically opposed bolts (11) on bearing carrier (13). In their place, screw two guide studs "G" into the tapped holes. Finishing removing the other bolts.
Extract carrier (13) using two bolts "V" of sufficient length placed in the tapped holes.


Take off the carrier (13) assembly / unit (15), shims (12) and 4 WD pinion (17). Visually note the position of the components. Remove circlip (5). Unscrew and remove bolts (8). Separate the carrier (13) and the unit (15).
Remove the discs (14), the intermediate plates (6) and handbrake mechanism (16). If necessary, extract the bearing cups (2) (10) and cone (7) on the drive pinion.

Refitting the drive pinion
If the drive pinion, taper roller bearings (7) (10) (1) (2), bearing carrier (13), thrust washer (4) and intermediate housing (19) have been replaced, it is essential to adjust the position of the drive pinion (bevel distance) and then shim the taper roller bearings.
Clean and check the components. Replace any parts found to be defective.
If bearing cone (7) has been disassembled, insert it to thrust against the drive pinion and cup (10) in contact with bearing carrier (13), using a press and an appropriate fixture. Lubricate the taper roller bearings (7) (10) with transmission oil.
Refit mechanism (16), the intermediate plates (6) and discs (14). Assemble unit (15) and carrier (13). Screw two diametrically opposed guide studs into the tapped bolt holes (11). Position and slide shims (12) on to the guide studs. Check that the 4 WD drive pinion (17) (if fitted) is oriented as shown in the overall view. Correctly position the carrier assembly (13) and unit (15) on the guide studs. Turn the drive pinion in order to engage the splines in pinion (17). Continue to push the unit assembly until it reaches its inserted
position.
Use the remaining bolts (11) and insert uniformly and alternately the carrier assembly (13) and unit (15). Remove the guide studs. Lightly smear bolts (11) with Loctite 270 and tighten them to a torque of 100 - 130 Nm.

Check that carrier (13) is in contact with shims (12). It is essential to place thrust washer (4) against shoulder "E" of the drive pinion. Slide on shims (3). Lubricate the bearing cone (1) with transmission oil and fit it on to the drive pinion in contact with the shims. Degrease the threads of nut (18) as well as those on the drive pinion.


Lightly smear the threads of the nut with Loctite 270 (or its equivalent) and immobilise it using wrench, ref. 3378118M1. Using socket, ref. 3378119M1, turn the drive pinion anti clockwise and tighten it to a torque of 200 - 250 Nm.
Take care to correctly position the torque wrench. Remove the tool. Manually check the rotation of the drive pinion. Lock the nut by bending the lock washer into the grooves of the pinion without breaking it, using an appropriate tool.
Fit pin (25) into the handbrake mechanism, correctly positioned to provide clearance. Place the washer and retaining pin. Adjust the control.

Final operations
Refit the hydraulic pump bearing / drive pinion assembly. Refit the ratchet and locking sleeve of the Park Lock transmission. Refit the creeper unit (if fitted). Adjust the fork. Couple the tractor between the intermediate housing and the centre housing. If replacement of the crownwheel and drive pinion has been carried out, check the backlash. Check the operation of all the controls.
Carry out a road test. Check the oil tightness of the mating surfaces.
Check the oil tightness of the hydraulic unions.

Adjusting the position and shimming the drive pinion

- It is essential to adjust the position of the drive pinion before carrying out shimming of the taper roller bearings (7) (10) and (1) (2). Under no circumstances should this adjustment be modified without readjusting the shimming of the drive pinion bearings.

Using a press, insert cup (10) thrust against bearing carrier (13).
Using a suitable fixture, insert cup (2) to thrust against housing (19). Screw in two diametrically opposed guide studs into the tapped holes (11). Fit the carrier alone without shims (12). Alternatively and progressively, tighten the four bolts (11) to a torque of 100 -130 Nm. Check that carrier (13) is in contact with the intermediate housing (19). Using a press and an appropriate fixture, insert cone (7) to thrust against the drive pinion. Lubricate the taper roller bearings (7) (10) with transmission oil.
Temporarily fit the drive pinion without shims (3) but with thrust washer (4) placed between the bearing cone (1) and nut (18). Pre-tighten the nut to a torque of 30 - 50 Nm using wrench, ref. 3378118M1 and socket, ref.
3378119M1 taking care to correctly position the torque wrench.
Turn the drive pinion several times to correctly seat the bearing cones in the cups. Check the correct pre-tightening of nut (18) again.

Adjusting the drive pinion position
The thickness of shims (12) required to position the drive pinion is calculated as follows: E = Z – (X + Y) where:
E : Is the thickness of shims (12) to be fitted, tolerance ± 0.05 mm.
Z : Is the nominal dimension between the rear face of the intermediate housing (19) and the axis of the differential crownwheel (20).


This dimension is stamped inside the housing in the horizontal axis of the differential unit.
Y : Is the nominal dimension of the positioning of the drive pinion = 139.00
X : Is the dimension measured between the end of the drive pinion and the rear face of the intermediate housing.


The drive pinion and the crownwheel are matched pairs and have a number and letter engraved on each component.


Using a depth gauge, measure dimension "X". After having taken the measurement, use the formula to determine "E", the thickness of the shim(s) (12) to be fitted in order to correctly position the drive pinion.

Checks
- Temporarily reassemble the assembly fitted with the previously determined shims and measure dimension "X" again.
- Check that X + Y does in fact equal Z.
Remove the drive pinion and bearing carrier (13). On bearing carrier (13), refit the mechanism, the intermediate plates, the discs and unit (15). Refit the assembly on the intermediate housing (19). Carry out operations.
- Carry out shimming of the drive pinion taper roller bearings.

Shimming taper roller bearings and of the drive pinion
On the drive pinion, slide the thickness of shims (3) required to obtain a provisional clearance of 0.10 mm to 0.15 mm maximum, in order to prepare P1 shimming. The thrust washer (4) must be placed against shoulder ‘E’ of the drive pinion. Lubricate bearing cup (2). Fit bearing cone (1). Using wrench, ref. 3378118M1 and socket, ref. 3378119M1, temporarily tighten nut (18) to a torque of 30 - 50 Nm.


Place the index of the dial gauge on the tapered end of the pinion. Pull strongly on the pinion via the front of the intermediate housing while alternately turning the pinion left and right to correctly seat the bearing cones in their cups. With the assistance of another operator, set the dial gauge to zero.


In relation to the clearance measured, select a new thickness of shims (3) in order to obtain pre-loading: P1 = 0.04 mm to 0.10 mm
Loosen and take off nut (18). Slide the shims (3) between thrust washer (4) and bearing cone (1). Degrease the threads of nut (18) as well as those of the drive pinion. Fit and definitively tighten the nut, its threads previously lightly smeared with Loctite 270, to a torque of 200 - 250 Nm. Manually check the rotation of the drive pinion. Lock the nut by bending its lock washer into the grooves of the pinion without breaking it, using an appropriate tool.