Gearbox repair
ALONG, long time ago, when I had only just started repairing Land Rovers for a living, a customer asked me to drop a Rover V8 engine into a Ninety in place of the 2.5 petrol lump with which it had left Solihull. I was delighted to be entrusted with such an interesting and frankly lucrative job, and set about the task with some enthusiasm. The job was complicated by the fact that the Ninety needed a new bulkhead. I had bought it unseen via an Internet auction site, bid good money on the strength of a few photographs, which made it look much better than it was, and then not been nearly brave enough to walk away when confronted with a Land Rover with the vent flap hinges no longer attached to the bulkhead, and a big shaven-headed vendor with a pit bull terrier and the general air of someone who would be rather handy in a pub fight.
The engine was the easy bit: I had acquired for breaking a totally-rotten Series III 109 V8 with a genuine 40,000 miles on the clock. I lifted both cylinder heads for inspection, confirmed that the bores were totally unworn, and buttoned the whole lot back together with a pair of SU carburettors from a Range Rover on top. But how to fit it to the Ninety? I had two options. The first was to use an adapter ring to mate the V8 backplate to the four-cylinder LT77 gearbox. This was a common enough conversion back in the old Series days, but brought a couple of problems with it.
The main issue was the engine positioning, well back in the engine bay if an adapter ring was used. Factory-built Ninety and One Ten V8s had the engine sitting close to the radiator with a very long gearbox bellhousing and input shaft, and Land Rover did that for a reason. Two reasons in fact: firstly because if the engine sat in the same place as the lesser four-cylinder lump the front axle would mash the oil filter flat in anything approaching serious off-roading, and secondly because there was insufficient room between the two footwells to provide clearance for the exhaust manifolds.
In Land Rover world everything is do-able and that includes fitting a V8 into the space previously occupied by a four: a remote oil filter mounted on the wing takes care of the first issue, and cutting and welding the footwells will deal with the second. But it would be better, I felt, to be able to put the V8 engine at the front of the engine bay where Land Rover intended, since I would then be able to use off-the-shelf hoses, exhaust system and engine mounting brackets. So I needed a longer gearbox. Two obvious possibilities presented themselves. One was to use the LT85 Santana gearbox deployed by Land Rover in factory-built V8s. This massively-strong, heavy and rather agricultural ’box would bolt straight onto the LT230 transfer box already in the Ninety, but the good news ended there. To shoehorn the LT85 into an Lt77-shaped space, the Solihull engineers had ended up having to redesign the floors, transmission tunnel, seatbox, gearbox mounts, transfer box linkage and propshafts. Most of these parts were only available secondhand, and no one seemed to be breaking a Ninety V8 at that particular moment.
So I started looking at the second option, which was to fit the long-stick LT77 gearbox from an early five-speed Range Rover. Like the LT85 this bolted straight onto my existing transfer box: unlike the LT85 it was externally identical to the four-cylinder gearbox as far forward as the bellhousing, so no major changes were required to make it fit. The long bellhousing bolted straight to the back of the V8, the input shaft snuggled happily into the spigot bush (using a conversion plate would have meant having a special thin-wall spigot bush made up) and the engine positioning was the same as a factory V8, give or take an inch or so. The LT77 might not be as strong a gearbox as the LT85 but I felt it would stand up to the power and torque of a low-compression 3.5 engine on carburettors, provided it was not mercilessly abused. The only problem was that I rang round all the breakers who had been out of stock of LT85S, and found they didn’t have any long-stick LT77S either.
At this point I came across something of a rarity for the time: an R380 gearbox out of a late first-series V8 Discovery, allegedly in good working order and very reasonably priced. Significantly stronger than the LT77 and about the same overall length, it seemed to meet all my needs, except that it had the short-stick gear selector mechanism which would have left me with the gear lever poking up through the seatbox where the customer wanted me to put a nice new deluxe cubby box. After trial-fitting the unmodified gearbox and V8 engine to the rolling chassis I consulted the parts book and workshop manual, concluded that it was probably possible to convert an R380 from short-stick to long-stick configuration, ordered new selector components and a gasket kit, and set about pulling the R380 to bits.
Nowadays this conversion is an easy one: Ashcroft Transmissions supply a very neat kit of parts with which you can convert an ex-discovery R380 to fit a Defender in a matter of minutes. But this kit was not available back then: the job required me to change the selector rail, which meant completely dismantling the gearbox. In theory I needed to purchase around £300 worth of special tools just to be able to remove the fifth gear extension
case from the back of the gearbox. I cannot remember how I got round this problem. I have a feeling I may have taken an angle grinder to the seal collar on the back of the mainshaft. We were all young once.
I managed to change the selector rail and fiddle the whole thing back together without too many bits left over. The engine sat exactly where I wanted it to, plumbing it in was delightfully easy (even the aftermarket performance exhaust system went on with no trouble) and on the road test the Ninety turned out to be a proper hooligan machine, with very brisk acceleration on the standard 1.410 transfer gearing and 235/70R16 tyres. I booted it a bit too hard on a narrow lane and only just managed to wrestle it back into shape before hitting a stone wall, which would have been awkward to explain to its new owner before he had even taken delivery. The only problem was that the gear change was a bit awkward and notchy. I told myself (and the customer) that it was just the new selector components bedding in, sent it out of the workshop and a week later it came back with the customer complaining that the gear change had if anything become worse.
Sure enough it was worse. I found a loose locking nut on one of the adjuster bolts on the gear lever turret. These bolts bear against the biasing springs which hold the gear lever central in the third/ fourth plane, and if they are incorrectly adjusted you end up trying to select an imaginary gear which sits somewhere between first and third in the gear change gate. So I tweaked the adjuster bolts and locked them down, dealt with a few other minor problems of the sort that emerge on freshly-rebuilt vehicles (doors not latching properly, wipers parking at an odd angle, that kind of thing) and set off on a long road test covering a circular route of around 30 miles, determined to ensure that the vehicle was 100 per cent in all respects and would not keep coming back to me for rectification work until Doomsday.
About half-way through the journey I started to get the impression that the gear change (which had been perfectly acceptable to start with) was getting notchy and obstructive. I changed up and down through the gears a few times which seemed to free it off a bit, carried on a little further and was just approaching the top of a hill on a dual carriageway, doing around 70 mph, when there was a humming sound which rapidly built into a loud shriek. I dipped the clutch and knocked the transfer box into neutral just as the main gearbox seized solid. Luckily the vehicle still had enough momentum to carry me onto the forecourt of a petrol station, where I ordered a large coffee and a recovery truck.
I never did find out why the gearbox had failed. By now I had rather lost confidence in my ability to work on the five-speed Land Rover gearboxes, so I ordered a reconditioned unit from a specialist, fitted it free of charge under warranty, ate dog food for a month while my wallet recovered, and thereafter shied away from any job which might involve pulling apart an R380 gearbox, or the closely related LT77. As it happens, reconditioned five-speed gearboxes are not dear, and faced with a worn-out gearbox it usually makes better economic sense for me to order a rebuilt ’box and let someone else bear the warranty cost if it goes pop.
However, I always had it in mind that one day I would have one of these gearboxes to bits again to see what it was made of and whether it could be easily worked on. I had a couple of suitable guinea-pigs lined up, an R380 and an LT77, both removed from non-driving Discoverys, untested and therefore pretty much unsaleable. But before I had the chance to dismantle them in a relaxed and leisurely fashion, fate intervened in the shape of a One Ten on a tight deadline and restricted budget, with an unexpected problem to add to the already far-too-long list of work to be done.
The vehicle was in to be fitted with a 300Tdi engine in place of a rather sick 19J turbodiesel, high ratio (ex-discovery) transfer box and a fair amount of chassis welding. I had road tested the vehicle before starting work and the gearbox felt fine with no noticeable clunks or rattles. Even so, in the back of my mind was the risk that removing the old transfer box might uncover something nasty. I wrote about this particular issue a couple of years ago: the transfer box input gear slides onto splines on the end of the gearbox mainshaft. Up to around 1995 these splines received no lubrication beyond a smear of grease at the factory, once the grease hardened with age and heat the splines would start to wear on both the shaft and the gear, until eventually there would be a loud bang (usually when moving off from rest in first gear) and total loss of drive. The transfer gear can be replaced easily enough without major dismantling, but to replace
the gearbox mainshaft, the gearbox must be completely dismantled, pretty much down to a bare casing.
When changing a transfer box I like to remove the input gear first, as it makes it easier to separate the transfer box from the main gearbox and then manoeuvre it backwards to clear the mainshaft before it can be lowered to the floor. Removing the input gear is simple. Undo the ring of six bolts securing the rear cover to the transfer box, remove the cover, the two bearing carrier screws (not fitted to later vehicles) and the carrier, and then simply slide the gear back off the mainshaft, turning it slightly to clear the intermediate gear cluster. This particular gear was jammed solidly onto the shaft and I knew I was in trouble. The splines had worn so badly that they had ended up wedgeshaped and had locked the gear firmly in place, rather like a taper shaft and pulley. A couple of well-placed hammer blows sorted that problem, but the gearbox mainshaft was scrap. Lead time for a reconditioned gearbox: ten days. Time available: four days. Number of good secondhand Defender LT77 gearboxes for sale within a 100 miles radius: zero.
So I had little choice but to try and repair the gearbox. And what surprised me, once I set about dismantling the gearbox, was how easy it turned out to be. An adapted bearing puller took care of the mainshaft collar, and an old spring shackle with a bolt welded to it proved perfect for locking fifth gear to remove the stake nut. Standard two and three leg gear pullers dealt with the rest. It is in some ways a nicer ’box to work on than the Series four-speeders with which I am intimately acquainted. I like the way you can stand the mainshaft and layshaft upright on the end plate, engage all the selector forks and simply slide the casing over the whole lot. So the gearbox went back together with a new mainshaft and a few other bits, and unlike my previous venture into five-speed gearbox repairs all those years ago, this time it worked faultlessly.
Looking at the time it took me to strip and reassemble the gearbox, and even allowing for a learning curve effect by which the next one will probably only take me half as long, I still don’t think there will be any cost saving for customers if I rebuild their gearboxes myself rather than buying them in. But at least I know I can have a Land Rover five-speed ’box to pieces and repair it if circumstances dictate. It seems you can indeed teach an old dog new tricks.