Series Land Rover gearboxes are more simple than those found in modern vehicles, but the DIY mechanic will still need a good basic grounding in general workshop techniques in order to accomplish a gearbox overhaul.
This brief article is not attempting to describe the detailed procedure for overhauling the Series I,II,IIA or III gearbox (small design features and several component parts were modified throughout the history of the Series Land Rovers). Step by step details of overhaul procedure can be found in both official and aftermarket manuals. Here I am attempting to set the record straight as regards accounts of what is and what is not possible; also advising on a more convenient plan of attack for the average Series Land Rover owner than the aftermarket manuals suggest.
Firstly, it is commonly stated that the Series gearbox can ONLY be removed through the passenger doorway and not through the driver's side. This is simply UNTRUE. Granted, it is more convenient
to do it through the passenger side but, if for any reason, access to that side of the vehicle is restricted, then the steering wheel is the only additional item that needs removing. Extra care must be taken to hoist the gearbox horizontally so as to be able to guide it past the steering column.
The most effective lifting points to achieve a horizontal lift are shown in the photo above. The rope is looped around the housing behind the transmission brake and the other end tied to the gear lever mounting bracket. Chain can be used, but rope is more convenient as a figure of eight loop can be tied in the central position: this ensures the crane hook cannot slide along and cause the gearbox to lift at a problematic angle. If chain is used, you need a ring in the central position else the hook may slide along, just as in the case of an un-knotted rope.
A mobile crane is the standard means of removing the gearbox from a Series Land Rover and it is important to note that the distance from the outer lower edge of the
door frame to the lifting point is the critical measurement: 32inch (80cm). This measurement is the same from either side of the vehicle. So, if you are buying a crane, note that it is not the length of the lifting arm that is critically important and yet this is usually the only measurement that is advertised. Suitable mobile lifting cranes available in the USA can be found on the tools page. The gearbox can also be removed by two people using a length of strong steel water piping but re-fitting is then more difficult unless either a third person is available to jiggle the gearbox into alignment with the clutch, or one end of the piping can be supported on e.g. a strong table.
When doing the job alone it can be useful to use a scissor jack to press the gearbox fully home onto
the flywheel housing.
But it's important not to try to force alignment, because the engine mountings can be damaged. All the flywheel housing studs should have entered their respective holes in the bellhousing before the jack is used to close them together.
If it is only the main gearbox that is to be overhauled, then it is not necessary to separate all four gearbox components (main box, bellhousing, transfer box and 4-wheel-drive unit): the bellhousing will need to be removed and the main gearbox separated, but the 4-wheel-drive unit and transfer gearbox can remain fixed together. A suggested procedure for main gearbox inspection and overhaul is:
1. Remove the 3 selector springs from the main gearbox, gear lever assembly and top cover
2. Remove the three gear selectors and then the bellhousing
3. Remove the input shaft and bearings from the bellhousing
4. Slide the roller bearing and synchro unit off the mainshaft
5. Lift out the layshaft
6. Remove the bearing cover plate and end cover from the back of the transfer box then remove the special nut, tab washer and gear from the back of the mainshaft.
7. Drive out the mainshaft from the back of the gearbox with a soft faced hammer
8. Remove the bottom cover to the transfer box
9. Release and pull out the intermediate gear shaft whilst supporting the intermediate gear by hand and then remove the intermediate gear
10. The transfer box can now be separated from the rest of the assembly by undoing the bolts from within the transfer box.
If you are lucky, you may not need to use either a blow torch or gear pullers to separate components. You may have all the tools required also (none of the special tools referred to in the official Series Land Rover repair manual are essential. But be prepared to have to stop work and obtain that one tool you don't have that halts progress.
If it is only the transfer gearbox and/or the 4-wheel-drive unit that is to be overhauled, then these can be removed from the Land Rover
without taking the whole gearbox unit out of the vehicle.
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