Refitting

1. Position the gearbox on the rotating stand (1a) using the support (1b).

1. Undo the oil level monitoring plug on the differential cover.

1. Undo the oil drain plug on the differential cover.

1. Undo the oil filler plug on the gearbox.

2. Undo and remove the reversing switch.

1. Undo the fixing screws (1a) and remove the rear cover (1b).

1. Use pliers (1a) to remove seeger ring (1b) from main shaft bearing.

1. Use pliers (1a) to remove seeger ring (1b) from upper layshaft bearing.

1. Use pliers (1a) to remove seeger ring (1b) from lower layshaft bearing.

1. Remove the shim from the lower layshaft bearing.

- Engage two gears.

The simultaneous engagement of two gears results in the gearbox shafts locking; this operation is necessary in order to be able to release the ring nuts securing the gears to the shafts.

1. Undo the ring nuts securing the gears to the gearbox shafts.

1. Undo the fixing screws (1a) and remove the gear selector/engagement mechanism (1b).

1. Loosen the fixing screws securing the gearbox gear casing.

1. Remove the gearbox gear casing (1b) using the fitting/extraction tool (1a).

1. Undo the fixing screws (1a) and remove the flange (1b).

1. Remove the differential casing adjustment ring.

1. Undo bolts (1a) and remove differential cover (1b).

1. Remove the oil seal from the differential casing (clutch side).

1. Remove the differential.

1. Extract from their seats the main shafts and layshafts complete with gears and gear selection levers with respective forks.

1. Extract the magnet from the seat and remove any metal particles that may be present.

1. Undo the clip fastening the connector, between the pipe supplying the clutch and the clutch release sleeve, to the sleeve.

1. Remove the connector between the clutch supply pipe and the clutch release sleeve.

1. Undo the fixing screws (1a) and remove the clutch release sleeve (1b).

1. Using tools (1a) and (1b), remove the main shaft bearing (1c) from the gearbox mounting case.

Check that the outer race, inner race and rollers are free of scratches, overheating marks and excessive wear, and that the bearing rolls freely without catching. Replace the complete bearing if this is not the case.

1. Using tools (1a) and (1b), remove the gear selection/engagement shaft bearing (1c).

Check that the bearing rolls freely and without impediment; if not, replace the entire bearing.

1. Undo the fixing screws (1a) and remove the oil duct (1b).

1. Use tools (1a) and (1b) to remove the shaft mounting bushes for the gear selection/engagement forks (1c).

Removing

- Wash the complete gearbox and gearbox gear casing.

1. Using tool (1a), insert the shaft mounting bushes (1b) for the gear selection/engagement forks into both the gearbox and the gearbox gear casing.

1. Position the oil duct (1a) and tighten the fixing screws (1b) to the prescribed torque.

1. Using tools (1a) and (1b), fit the gear selection/engagement shaft bearing (1c).

1. Using tool (1a), fit the main shaft bearing (1b) onto the gearbox casing.

1. Fit the differential casing assembly (1a) with associated bearings (1b) and (1c) onto the gearbox casing.

1. Position the differential casing cover and tighten the bolts to the recommended torque, following the order shown.

Tightening torque for screws 1 to 4:

Tightening torque for screws 5 to 14:

1. Bed in the differential sealing cover side differential bearing outer race.

1. Fit tool (1a) complete with dial gauge (1b) on the differential sealing cover support surface, then move the probe into contact with the taper roller bearing outer race.

Zero the dial gauge with a preload of 1 mm.

1. Position tool (1a) complete with dial gauge onto differential sealing cover (1b), as shown in the figure, and measure the difference.

Calculate the thickness of the thrust ring for the differential bearing pre-loading by adding 0.23 mm to the difference measured.

The value of 0.23 mm corresponds to the recommended interference for the bedding in and pre-loading of the differential bearings.

If one, or the sum of two, registration rings available does not correspond exactly to the value produced in this way, fit one or two rings with a total thickness that is the next largest.

1. Place the thrust ring (of exactly the same size or the next largest size to that calculated for the differential bearing pre-loading) in the housing.

1. Position the differential sealing cover and tighten the fixing screws to the prescribed torque, respecting the order shown.

1. Using a dynamometer (1a) and special tool (1b), check that the rotational torque of the differential unit falls within recommended values.

- Unscrew the fixing screws and remove the differential sealing cover.

- Remove the differential bearing preload thrust ring from its housing.

- Undo the fixing screws and remove the differential casing cover.

- Remove the differential casing assembly with respective bearings from the gearbox casing.

1. Position the magnet in its housing on the gearbox casing.

1. Position the gearbox shafts, complete with respective gear selection and engagement forks, in their seats on the gearbox casing.

2. Distribute a uniform layer of sealant over the entire contact surface between the gearbox casing and the gearbox gear casing.

1. Fit the gearbox gear casing (1b), using the fitting/extraction tool (1a).

1. Tighten the screws fixing the gearbox gear casing to the prescribed torque in two successive stages, following the sequence shown.

In the first stage tighten all the screws to 50% of the rated torque.

In the second stage tighten all the screws to 100% of the rated torque.

1. Position the shim of the lower layshaft bearing.

1. Using pliers (1a), position the seeger ring (1b) onto the lower layshaft bearing.

1. Using pliers (1a), position the seeger ring (1b) onto the upper layshaft bearing.

1. Using pliers (1a), position the seeger ring (1b) onto the main shaft bearing.

1. Position the gear selection/engagement mechanism (1a) and tighten the screws (1b) to the prescribed torque.

- Engage two gears.

The simultaneous engagement of two gears results in the gearbox shafts locking; this operation is necessary in order to be able to tighten the ring nuts securing the gears to the shafts to torque.

1. Tighten the ring nuts fixing the gears onto the gearbox shafts to the prescribed torque.

1. Position rear cover (1a) and tighten the fixing screws to the prescribed torque in two successive stages, following the order shown.

In the first stage tighten all the screws to 50% of the rated torque.

In the second stage tighten all the screws to 100% of the rated torque.

1. Fit the differential casing assembly (1a) with associated bearings (1b) and (1c) onto the gearbox casing.

2. Distribute a uniform layer of sealant over the entire contact surface between the gearbox casing and the differential casing.

- Refit the differential casing cover, the differential bearing preload thrust ring and the differential sealing cover, as shown above.

1. Position the clutch release sleeve (1a) and tighten the screws (1b) to the prescribed torque.

1. Insert the connector between the clutch supply pipe and the clutch release sleeve.

1. Insert the fastening clip for the connector, between the clutch supply pipe and the clutch release sleeve, into the sleeve.

1. Tighten the fluid level monitoring plug on the differential cover to the prescribed torque.

1. Tighten the fluid drain plug on the differential cover to the prescribed torque.

1. Tighten the fluid filler cap on the gearbox casing to the prescribed torque.

2. Tighten the reversing switch to the prescribed torque.

1. Using the tool (1a), fit the oil seal (1b) on the differential casing (clutch side).

1. Using tool (1a), fit the oil seal (1b) on differential casing (gear casing side).

1. Using a dynamometer (1a) and special tool (1b), check that the rotational torque of the main shaft falls within recommended values.

- Support the gearbox using a hydraulic lift.

- Undo the fastenings and remove the gearbox and differential from the support tool.

- Remove the support tool from the overhaul stand.

- Position the gearbox and differential on a suitable platform.