Difference in UN1 to UN5 gear sets?

[Steven]

I'm hoping the GT40 "Brains Trust" can shed some light on any difference between the UN1 and the UN5, that would stop the use of the Albins UN5 1st and 2nd gear set in the UN1 case.
Albins cant tell me.
Possible problems maybe: Different centers spacing, primary to secondary shafts, difference in bearing ID's?
I do know the final drive is a bigger in diameter and further forward in the UN5, but as the Albins gear set uses the standard secondary shaft with new 1st and 2nd idler gears, pinion position remains correct with the use of the UN1 secondary shaft and final drive. Lastly the primary shaft seal is in a different location between the two transmissions but this is a minor problem. Albins need to know the reverse idler tooth count to supply the correct UN5 gear set, which makes me think if my UN1 has the same tooth count this maybe all that is needed to find the right gear set, as I have been told the UN1 was upgraded in production and the reverse idler also changed at the same time, perhaps the bearings where upgraded to the same as the UN5, Yes I'm grasping at straws now.
So does anyone know of anything stopping the swap?

Thanks
Steven

 

[Danny]

Are you in Sydney and is your box the UN5? I have a few boxes, UN1, Esprit, 367 and 369 as well as parts from the UN5. Interested also to do a comparison.

What are your plans for the diff?

 

[Steven]

Hi Danny

Yes mine is a UN1 and I have fitted it with a ATB from GTO RACING | Homepage - Renault UN1 Lotus Esprit GT40 Transaxles
Im in Wollongong, but get to Sydney often. Do you have a UN5 case or shaft? I could come up and measure them.

 

[Danny]

You're not too far away. PM with my phone numbers sent.

 

[Kevin Box]

Just looking through some old posts and I am curious as what the final outcome was ????


Thanks

KevinB

 

[Stephane Goria]

Quick answer :

The distance between the reverse idler and the shafts is different between a UN1 and a UN5.

This wasn't true with the very first UN5 gearboxes, (un5-01 to UN5-03 if I remember well).

Thus, if the albins upgraded shaft has been made upon the specs of a later un5, it won't fit without modifications to the gearbox housing but if made from an earlier UN5 it will...

The modification to do is to offset the idler shaft, this requires some welding.

I did it once some years ago to adapt some internals of a un5 into a UN1 housing in a configuration where I had to keep the UN1 housing (cronwheel offset).

Greetings

Stephane