Specifications, Service and Repair of Farm and Lawn Tractors


Massey Ferguson 8250 Power Shuttle gearbox - Removing and install the rear clutch

Remove the MF 8250 front clutch. Remove the input unit.

Remove the screws (70) and remove the cover (38).
Recover the spools (44) and the springs (45)
Remove the thick springs (62) and the pins (71).

On cover (38), remove:

- the plate (43)
- the seal (42) and discard it
- the piston (39)
- the seals (36) (41) and discard them
- the unions (72), the 13 bar valve (77) and seal (75) on the 17 bar supply port.

Immobilise planet carrier (49).
Remove screws (99) securing the cover (34) and remove it.
Remove the discs (47) and the intermediate plates (46).

Separate the output sun gear (58), held by the snap rings (61), from the primary shaft (55).
Remove snap ring (98).
Remove the planet carrier (49) with the double and single pinion gears (52) (59).

On the planet carrier (49), remove:

- the plates (63)
- the double pinion gears (52) and the pins (50). Note and mark their location.
- the single pinion gears (59) and pins (50). Note and mark their location.
- the snap ring (56) and bearing (57).
- rotation of pinion gears around the pins (50) is on two rows of needle bearings (60), joined and separated by a spacer (51).
- if the pinion gears and the pins are to be removed, check that no unwanted needle or spacer remains in the planet carrier after refitting.

Clean and check all parts. Replace any defective ones. Check that the ports in the pinion gear pins and the channels in the planet carriers are not clogged.

Where necessary, fit the pinion gears with two rows of needle bearings coated with miscible grease and separated by a spacer.

On the planet carrier, refit:

- bearing (57) and position snap ring (56),
- the double and single pinion gears (52) (59) positioned,
- pins (50), with the lubricating ports placed facing those in the planet carrier (49).

Each end of the pins (50) contains:

- a port, one of which is closed off by a rivet (35) while the other is used for pinion gear lubrication,
- a flat and a shoulder that stop any pin rotation or any side movement.

Install the partially assembled planet carrier. Fit the snap ring (98) and the rear snap ring (61) on the output sun gear (58). Position marks "R" (punch marks) on the double pinion gears (52) so that they pass through a centerline meeting at "O".

The mark on the front side of the planet carrier corresponds to the alignment of the two splines. It is mandatory to respect these positions of the punch marks during assembly of the output sun gear (58).

Slide the output sun gear (58), correctly oriented, on to the primary shaft (55), making sure that the punch marks of each pinion gear remain in the required position.

Install the front snap ring (61). Soak the discs (47) in a Massey Ferguson 8250 transmission oil bath for approximately 1 hour. Check that they are correctly saturated.

Install the discs (47) and the intermediate plates (46) depending on the type of tractor. Check that the centering pin (17) is fitted. Install cover (34).

Check that it is correctly positioned on the pins (50) of the pinion gears and in the centering pin. Immobilise the planet carrier, using the same method as used during disassembly.

Fit and tighten screws (99) to a torque of 36 - 46 Nm with the threads previously lightly smeared with Loctite 242 or equivalent.

On cover (38), check for the presence of rivets (40) at the end of the channels and refit:

- piston (39) with new lubricated seals (36) (41), gradually and alternately striking around the piston rim with a plastic mallet. Check that no fragments of the seal remain after assembly,

- plate (43) with a new lubricated seal (42), aligning the holes of the plate with those in the cover (38).

Insert the plate using the same method as used for piston (39). The thickness of the plate (43) differs according to the number of discs and intermediate plates.

Refit pins (71) and springs (62) in their respective locations on the input unit. Coat the spools (44) and the springs (45) with miscible grease.

Fit and stick the spools in each compartment of cover (38), with the points towards the unions (72). Slide and stick a spring (45) in each spool.

On the outside face of the cover (38), place three sufficiently long and equally spaced studs in the holes provided for screws (64).

Install and position the cover, with the 13 bar valve port (77) turned upwards. Before fitting screws (70), check that the spools (44) slide freely in each compartment of the front cover on the input unit.

To do this, compress the springs (45), using a screwdriver passed through the tapped holes of the unions (72). If the springs cannot be compressed, it is important to find the reason. Pre-tighten screws (70).

During pre-tightening, check that the spools (44) still slide freely. Also check that each end of the springs (62) are correctly housed in their bases.

Definitively tighten the screws (70) to a torque of 29 - 37 Nm. After completing the tightening, check the sliding movement again and return of each spool to its initial position.

A spool that is blocked open may limit or interrupt lubrication to the Massey Ferguson 8250 front clutch.

Install the 13 bar valve (77) with its seal on cover (38) and tighten to a torque of 12.5 Nm - 13.5 Nm maximum. Fit and tighten the unions (72). Install the input unit and the front clutch.

Disassembling and reassembling the driving pinion - Shimming the shaft

The rearward position of the Dynashift, caused by the presence of the rear shuttle clutch in the housing of the unit, limits the space available at the rear of the input unit. This is why the secondary shaft (1) and the pinion (2) are machined as a single component.

Remove the MF 8250 tractor front clutch. Remove the input unit. Remove the rear clutch. Remove the Dynashift device. Pair bearing cones and bearing cups together if they are to be re-used.

Remove screws (13) and casing (5). Recover the locating pin (4). Where necessary, remove bearing cup (16) and shims (3). Take out the secondary shaft (1), pinion and bearing cones (7) (9) assembly from cover (14).

Remove bearing cup (8). Where needed, separate the bearing cones from the shaft. Drive out the roller bearing (1), the gearbox front intermediary shaft support. Take off oil deflector (2) and discard it if necessary.

Check that the ports of the secondary shaft are not clogged and check for the presence of lubrication restrictor "R"
Clean and check parts. Replace any defective ones.

Lubricate the bearing cones and cups with MF 8250 transmission oil before assembly. Insert bearing cones (7) (9) in contact with pinion (2) using a suitable press and fixture. Place the bearing cup (8) in cover (14). Install the secondary shaft (1), pinion and bearing cones assembly inside the cover.


Determine the thickness of shims (3) required in order to obtain a temporary clearance of 0.10 mm to 0.15 mm approximately. Place the previously determined shims in casing (5) followed by the bearing cup (16).

Place the locating pin (4) and the unit on cover (14). Tighten screws (13) to a torque of 29 - 37 Nm. Place the unit in a vice with jaw protectors, and carry out a definitive shimming of the shaft.

Shimming the shaft (1). The principle consists in determining a thickness of shims (3) to fit between the bearing cup of bearing (16) and casing (5).

It is recommended to remove oil deflector (2) in order to avoid any interference between it and the shaft (1).
Position the feeler of the dial gauge on the end of the shaft.

Pull hard on shaft (1), alternately turning it from left to right in order to correctly seat the cones in the bearing cups.
Set the needle of the dial gauge to zero. Repeat operation 118 this time while pushing.

Depending on the clearance measured, select a new shim thickness (3) to provide a preloading of: P1 = 0.05 mm to 0.15 mm - Where possible, shim to the maximum tolerance.

Remove screws (13). Remove casing (5). Position the definitive shims (3) selected during along with bearing cup (16) in the casing (5).

Install the casing, shim(s) and bearing cup assembly on cover 14, first checking for the presence of locating pin (4).

Fit and definitively tighten screws (13) to a torque of 29 - 37 Nm, the threads previously smeared with Loctite 242 or equivalent. Manually check the rotation of the shaft.

Turn the oil deflector (2) and insert the roller bearing (1) in thrust against the unit housing. Install the Dynashift device. Install the rear clutch. Install the input unit. Install the front clutch.