UN1 Input Shaft

Sorry if this covers old ground, but I've been unable to nail down anything in the search function.

Pulled my (20 year old but brand new) UN1 apart to flip the crown wheel. I'm inverting the box to lower the input shaft. A fairly simple box, but the input shaft is a nonsense. I'm surprised it can handle more than 100HP. Dinky little splines that would be easily shredded by any real torque.

So I'm looking at a replacement one piece input shaft. Having contacted Albins (Australia), they have apparently only ever made one. An English firm has quoted something over 2400 quid, a bit more than I'm prepared to pay for a bit of machined shaft.

Strikes me that by sourcing a same OD, larger ID input bearing, a one piece input shaft could be machined up, with an increased overall diameter. OK, this may only be 1 or 2 mm, but every little bit helps. This larger OD could mean that the clutch plate spline OD could also be increased, giving a far larger range of potentially useable clutch plates.

This shaft would require a clutch plate spline, a straight cut gear (reverse?), 2 helically cut gears, and a threaded end. And, I assume, some ground finish surfaces.

Given the potential market from not just GT40 fans, but Lotus and the off road guys, I am puzzled that no-one is advertising that they sell this sort of shaft at an affordable price.

I am exploring the local manufacture, to at least get a sensible cost.

But if anyone has a supplier they can recommend, I would certainly be interested.



GT40s Supporter
Locally you could try these guys www.eurospeed.com.au/UN5.htm

Re your request for upgraded replacement parts -- Firstly , there's better trans choices out there! Secondly , finding a specialist machine shop who knows his stuff (such as Albins) will custom make to your order .
To produce this part requires a capital investment of machinery and treatment plant at around $1/2 M min.
A lathe, spline hobbing mill, helical hypoid bevel gear generater, precision cylindrical grinder, heat treatment facility,. QA, warranty etc The engineeering knowledge from someone who knows his steels and their treatments.

Aaand the fitter, precision machinist / toolmaker is one of the poorest paid trades in this country :cry: ---(have you seen what a plumber gets for what he does --don't get me started...)
Your right Albins only made one and it happens to be mine I designed it and they built it for me. If your interested they could probably make me another one and note on the pictures that first gear is NOT a straight cut gear like all the rest are.



Many thanks for those pickies. It makes explaining my requirements really easy.

Looks like a lovely bit of work. Was much work required to adapt the r/h end gears to the new shaft? (Showing my ignorance - I've yet to dismantle mine to understand the various gears). It looks to be considerably larger diameter than standard, and requiring the gear cluster internals to be bored out.

I will be approaching local gearmakers with the photos.

Chris, I fully appreciate that particular trades require very expensive machines, with skilled operators. But if you can manufacture and sell 50 widgits instead of one, the price should come down. I think the competition to provide low cost remanufactured V8 motors illustrates this well.

Having said that, I also have some serious machinery for my business, but I'm being beaten to death by amateurs with el cheapo Chinese machines and no overheads doing it for bugger all.


I have a Rover V8, with a Renault UN 103 gearbox,and I want to invert the gearbox.

I have heard of people, cutting the bell houseing in half, turning it 180 degress, and then welding it. It has also been sugested to me that it may be possible to make an adoptor plate to go between the gearbox, and bell housing...

Any information you can give would be greatly appreciated



At this stage I am running an adapter plate (10mm alloy). I may need to finness it a bit, but it certainly all bolts up at the moment.

Running a smaller diameter flywheel to fit the Renault bellhousing, and will use a concentric slave cylinder.


I have delivered the shaft(s) to AMPA Engineering in Sydney, as a result of a favourable comment from a fellow 40's member in a post on this forum.

Tom (the epitome of the aged craftsman) explained that the manufacture of the shaft would not be easy to replicate, but I should leave it with him for further thought.

It's been a couple of weeks, so maybe I should touch base.

I will keep all informed.

Still puzzled that the NZ end of the equation is totally silent. Seems they've been there, done that, but have no interest in providing new product. Strange.


With the gearbox in pieces, I have been able to bolt the bellhousing to the motor, and use the input shaft housing to ascertain that my centerline measurements were out by about 2mm. I need to sit down and finess the bolt pattern, and look at getting the strongest bolt pattern.

Hence my tardiness in posting a .DXF file. When I get it right, I will post it.

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