Mix and match
ONE of the reasons old Land Rovers are so interesting to work on is that you can see how the basic design evolved over time, from the original 1948 Series I to the Defender. The 1970 Range Rover provided an injection of fresh design ideas which worked their way through the product line, with the Ninety and One Ten being essentially a crossbreed of Series III and Range Rover components. The Discovery 1 was basically a reskinned Range Rover with a new diesel engine, and it was only when the first-generation Freelander and P38 Range Rover appeared that the link was broken, these vehicles sharing very few mechanical or structural components with what had gone before.
As a result there is a great deal of interchangeability between different models. Land Rover’s owners (firstly Rover, then British Leyland) were forever short of cash, and when new designs were introduced, wherever possible the tooling for the previous version was reused or adapted. The 200Tdi engine provides a good example: the cylinder block was designed to be machined on the same transfer tooling as the outgoing 19J turbodiesel (itself a progressive development of the 1957 Series I diesel engine), which is why a 200Tdi is so easy to fit into an older Land Rover. Even when the block was comprehensively redesigned for the 300Tdi, which shares barely a single component with the 200Tdi, the same transfer tooling was used again. The 300Tdi block has several threaded holes in it which serve no purpose whatsoever, other than to remind us that in Solihull old tooling never dies.
As these vehicles age and some components become hard to find, it is often quicker and cheaper to adapt a component from an earlier or later model than to find the correct item. Armed with a pile of parts catalogues and a basic knowledge of the development timeline, it is usually possible to find a way to work around a missing or damaged component. I found myself putting this to the test when a customer brought me a large box full of gearbox components which he had acquired. He had been assured that the parts would build up into a complete Series IIA gearbox and wanted me to do just that.
I had a rummage through the box and spotted a problem straight away: although most of the bits looked to be Series IIA items, the bellhousing was from a Series III. This meant that it had the mounting points for a horizontal clutch slave cylinder cast into it. Series IIA and earlier gearboxes have a vertically mounted slave cylinder on a separate bracket, with a crank and cross shaft to transmit movement through an oval aperture in the side of the bellhousing. The Series III arrangement, with a pivoting cast fork and replaceable release bearing, is a simple and robust design but will not fit in a Series II / IIA chassis as the slave cylinder fouls one of the strengthening gussets on the chassis crossmember underneath the bellhousing. It would be possible in theory to make a blanking plate to cover the slave cylinder hole in the bellhousing, but I didn’t fancy my chances of cutting an oval hole through a thick aluminium casting, on a diagonal and in exactly the right place to accommodate the Series IIA cross shaft and its rubber seal. I needed a Series IIA bellhousing.
The gearbox which this was being built to replace was still in the vehicle. The serial number on Series II/IIA gearboxes is stamped on the right hand side of the top cover and most of it was covered by the
overdrive lever bracket, but I could just make out the suffix letter E. Early Series IIA gearboxes had a small front layshaft bearing carried over from the Series I: from suffix B onwards the layshaft was strengthened, with a larger bearing and a slight bulge in the edge of the front cover to accommodate it. So the plan I agreed with the owner was that I would put together the new gearbox up to the point of needing the bellhousing (which is just about the last bit to go on), then remove his old gearbox and transfer the bellhousing and front cover onto the new one.
I cleaned and inspected the components and realised that the job was not going to be a simple reassembly. Third gear had seized onto the plain phosphor-bronze bush on the mainshaft, and the back end of the shaft was damaged as well. I had an incomplete Series IIA gearbox which had been gathering dust in a corner for ages, having come in with a job lot of other bits. This was a suffix F box and had a fair few bits missing, but yielded a good mainshaft, bush and third gear among other useful parts. Series IIA gearboxes are simple old beasts with very little in the way of shims and bearing preloads to worry about and I soon had a complete transmission (less bellhousing) sitting on the bench.
The next stage was to get the vehicle into the workshop and pull out the gearbox. It was a lovely old Series II, 88in truck cab in grey, fitted with an unusually sweet-running five-bearing Series III diesel engine, in very solid condition all round and oozing period charm. On most Series vehicles the gearbox crossmember is welded to the chassis, so the gearbox has to come out through the passenger compartment after removing the seatbox. This can be a long and tedious job when the vehicle has not been apart for many years. The floors and transmission tunnel have to come out and the threads on most of the bolts and screws (of which there are very many) will inevitably be badly rusted and seized. On this vehicle the owner had done most of the hard work for me, with just half a dozen bolts to undo.
I hoisted the gearbox out with an engine crane and immediately spotted a problem. The front cover and bellhousing were the early (Series II) type, which meant that the gearbox had a small front layshaft bearing. With the gearbox out of the vehicle I could finally see the serial number which showed that the gearbox itself had started life in a six-cylinder petrol Series IIA, which has a
different bellhousing stud pattern to the four-cylinder engines. What I did not know was how many other parts had been changed to make the Series II bellhousing fit. Time to get out the parts catalogue again, and after studying it carefully over a cup of tea I concluded that I could marry the small-bearing layshaft and bellhousing to my rebuilt Suffix E gearbox. The result is not as strong as a pukka Suffix E unit, and it will baffle and confuse the next person to rebuild it in about 20 years time, but the alternative would be to try and track down a late IIA bellhousing, and such things are not as easy to find as they once were.
While the gearbox was out I took the opportunity to replace the crankshaft rear oil seal which was showing signs of oil seepage. After endless problems with various aftermarket seals (even OEM labelled ones) I finally did what I should have done years ago and placed a large order with Turner Engineering for the high quality Corteco seals that they use in their own engines. These look to have a steel rather than aluminium case and do not come pre-coated with sealant, but they press into the housing with just the right amount of force. Most rear crank seals come with a plastic guide to ensure that the seal lip slides over the end of the crank journal without being damaged. Usually these guides are crudely moulded and quite thick at the edges but the Corteco ones are rather better than most, and the new seal slipped into position with minimal effort. A new AP Driveline Series IIA diesel clutch completed the work at the back of the engine, and it was not long before the gearbox was bolted in, vehicle road tested and ready to be collected.
Many people seem to be wary of working on gearboxes. Dave the Landlord regards them as the devil’s own invention and won’t touch a gearbox overhaul with a ten foot pole. The sheer number of components can seem daunting at first and I must admit I would think twice before pulling apart a modern eight-speed auto box, but the old Series gearbox is just about as simple a gearbox as you will find, all the components work in a obvious way (once you have understood the basic principles of a constant-mesh gearbox) and like most Land Rover mechanicals of the Series era, the whole thing can be dismantled and reassembled using basic hand tools. Access to a hydraulic press makes the replacement of the mainshaft bearings a little easier but there are ways around that problem.
I currently have another Series IIA gearbox in bits, on which someone had tried removing the rear mainshaft bearing by hitting the end of the mainshaft with a hammer, causing it to mushroom slightly. This meant that the rear support bearing no longer slid over the end of the mainshaft: hammer marks on the rear cover showed how the rebuilder had overcome that problem. The idiot had also failed to tighten the four large bolts which attach the bellhousing to the main casing. The gearbox was in a project vehicle sent to me for finishing off – I filled the gearbox with oil and it all trickled out onto the floor. When I dismantled the gearbox I found that the third/fourth synchromesh hub had been fitted the wrong way round. Even if the gearbox had retained its oil it would almost certainly have jumped out of third gear when road tested. Some people should not be allowed to own tools.
As an aside, I have just stripped down a Series III for a chassis replacement and that has a very peculiar bellhousing which I have never seen before. It has the Series III slave cylinder mount and the Series IIA cross shaft aperture. The latter looks to be a factory job. I don’t know whether this was produced by Land Rover as a universal bellhousing for Series IIA and Series III gearboxes, or whether it is an aftermarket part. I would be interested to hear from anyone who can shed some light on this mystery.