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5 Speed Gearbox Conversion - Carl Hayward

The article below appeared in the Spring 1996 edition of the Locust Enthusiasts Club Magazine which at the time was called the Locust Experience.


Carl Hayward Fits A 5-Speed Gearbox

I've owned my Locust for almost two years now, having bought it in a roadworthy condition. In that time, I have probably changed everything on it that the original owner/builder had constructed it with; from the wiring to the wheels, the engine to the exterior panels, and the dashboard to the drive-shaft. I hasten to add that none of this would have been possible without the help of my father's considerable engineering experience and expertise. Geoff, a family friend who is a Technology Teacher and who has built from scratch his own T & J Hornet and aided others in the construction of various other kit cars, and most importantly, my mother Lynda, who has endured years of tea and coffee making, greasy hand towels and sinks, and generally putting up with every trait that an enthusiast (and associates) has, whilst developing his new found relationship with his kit! ....... you all know what I mean, don't you?

Anyway, back to what this article is really all about. My Locust was built in 1992/93. It is currently powered with a 1700cc Ford Crossflow from Vulcan Engineering in Hanwell, Middlesex, and until a short while ago, this was mated to a very old Ford 4-speed gearbox. This gearbox had obviously passed its sell-by date due to its inability to select second gear when given serious stick in first gear off the line (very embarrassing), popping out of third gear on the overrun, and leaking oil like a sieve, not dismissing the fact that in top gear at 65/70 mph the engine was screaming like a banshee. There was no other solution, a 5-speed gearbox had become the next job on the list.

I spoke to a friend of mine who co-owns Power Engineering in Uxbridge, to ask him the going rate for a second-hand 5-speeder. He seemed to think 150 was about the price to expect. I went down to my local breakers yard, explained my situation and I was directed towards no less than three gearboxes. I cast my mind back to what I was told about checking the box. First, try the gear lever and make sure you can select all five gears, plus reverse. Then remove the top cover and have a good look inside. Rotate the spigot shaft and have a look for cracked or chopped teeth and anything floating around inside! Also check the play on the spigot shaft. There should be a small amount of up and down play, this enables the shaft to connect with the clutch housing. There should be minimal play, if any, in or out on the spigot shaft. Check also, the mounting point for the cross brace at the tail end of the gearbox (one I looked at had been cut off with a hack-saw!), make sure you get the cross brace and the gear lever with the purchase, and also you will need the tail shaft which slides in the back of the gearbox where you attach the propshaft (you need this as the diameter of a 5-speed tail shaft is slightly larger than the 4-speed, if you're replacing a 4-speed that is). If it's known, get the history from the breakers as to how the gearbox came into their possession. The way in which the vehicle ended up in the 'scrappies' may have a bearing on how well you think the gearbox should be. At the end of the day, you're buying a second-hand component, you may be lucky with your choice, you might not. However, most breakers give a seven day exchange guarantee, so fit it soon after, should you buy it.

After checking a couple of gearboxes, I set my heart on one from, I believe, a 2.0 litre Sierra. I asked how much, and was told 150 (funnily enough). It would have been slightly cheaper had I been exchanging it for another 5-speed gearbox, and he wasn't interested in my 4 speed box! Money exchanged hands, and I was the proud owner of a 5-speed gearbox. The next daunting task .............. to fit it!

Along with my trusted companions, we jacked the Locust up, stood it on axle- stands and started to unbolt the gearbox and ancillaries. Geoff told me that he had seen a box come out the bottom of another Locust without removing the engine. However, my car had to be different. With the propshaft off, gearbox detached, would it drop out through the chassis rails, .............. would it'eck!

This left us with the task of taking the whole lot out. We bolted the gearbox back onto the engine and then started to remove the 'gubbins' in the engine bay in order to take the lot out. Once the nose cone and radiator were out of harms way, it all came out effortlessly. Having done this, we bolted the 5-speed to the engine and put it back again. In no time at all we came to realise three things. Firstly, the gearbox would fit, secondly, the gear lever would come up through the tunnel in an ideal position, thirdly, the bottom chassis rails were too close to the bottom of the gearbox, giving us no room for engine/gearbox movement under power and the gearbox wouldn't sit level ............... RATS!

So, out came the engine and gearbox again. We were getting good at it now. Armed with a hacksaw we cut away the lower lip of the angle iron (which the gearbox cross brace sits on) about 4 or 5 inches back from the end starting at the engine bay. The engine and gearbox were put back in and hey-presto everything was starting to look hunky-dory. However, there was no longer a ledge for the cross brace to sit on to support the tail end of the gearbox. This was remedied by bolting a piece of angle on each end of the cross brace so that we could use the vertical edges of the lower chassis rails (below the gearbox) to bolt the cross brace up against. Now, these cross brace mounting bolts are more accessible as they run horizontally through the angle of the chassis, rather than vertically, up through it, where its always fiddly getting the nut on the bolt when your hand is sandwiched between the gearbox and the tunnel.

Anyway, by now things were taking shape. The gearbox was sitting level and all associated 'bits' were clear of their 'bobs'. We took the engine and gearbox out again, this time to install the clutch, and bolt everything up tight. The clutch we had to use (because of the number of splines on the crankshaft) was from a 1.6 litre, 5-speed Sierra, along with this we bought a new thrust bearing. With the gearbox now finally attached to the engine, in it went.

The propshaft would have fitted, but we needed the 5-speed tailpiece attaching to it. We took it to Propshaft Services, near Heathrow, and for £75.20, they replaced the tailpiece, shortened the shaft by 3/4 inch (as requested), balanced it and sprayed it a lovely shade of black. A day or so later, the propshaft was. on. In the meantime, we had been cutting holes in the top of the tunnel to accommodate the gear lever. This was a relatively painless task with the gear lever sprouting out from the back of the box as it was originally intended. The only modifications were to use a Quick shift kit from Burton's which has dramatically reduced the distance between each gear change (this involved a little manipulating of the original gear lever) and to put a swan-neck in the lever, so that in 1st, 3rd, 5th and reverse, there is room for my hand between the gear knob and the bottom of the dashboard.

The one thing we hadn't done was to replace the starter motor. I offered it up to the bellhousing, but it wouldn't seat properly! Bother, I cried. I took it back out and had a look in and guess what. The hole in the metal gasket (between the bellhousing and the engine) which the starter passes through, did not line up with the hole in the bellhousing. This can be attributed to the fact that I had used the bellhousing that the 5-speed gearbox had come with, and although I had compared the numbers stamped on the outsides of both bellhousings, there was a slight difference. This was suitably cured with the use of (ashamedly) a cold chisel and hammer. Soon we were smiling again as a quick test of the starter motor in position with the spark plugs out allayed our greatest fears of having to bump start the bloody thing wherever we went!

By now, we were very close to its maiden voyage. After putting synthetic gear oil in the gearbox (don't use a hypoid in a 5-speed, as its a b"*'*d to change gear when it's cold), we were ready for the off ............... Oh the anticipation!

In I got, started it up dumped it in gear, and off I jolly well trotted. I simply couldn't believe the transformation. The gearbox felt so smooth, the gear change so positive, and to be able to cruise along at speed with the rev counter only showing 3000 rpm was sheer delight, oh this had to be one of the most beneficial (and not to mention 'reasonably' straight forward) changes that we've made.

There were no strange noises, no more jumping out of gear and I think my fuel consumption must have improved, although this is mere judgement as the ratio between the Ford 5-speed gearbox and my Triumph Dolomite speedo are now greater than before. Now I've apparently had 110 mph out of it, and my 0-60 time is about 5 seconds. I think my 10% speedo error is more like 30%! Still, it impresses my passengers (they're not to know). The car is now ever so much more driveable, and I don't know how I ever coped with the 4-speed gearbox. The BIG QUESTION. How much did it all cost then, Guv'nor? Well, Here is what I bought:

Propshaft shortened/balanced
Clutch/thrust bearing
Quick-Shift Kit
Synthetic gearbox oil

Total cost, a few washers short of 300. Yes I know its more money spent on the 'blessed' car, but let's face it, it was well worth it!

Carl Hayward.


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