UN1-013 5th gear

Rob Bromfield

GT40s Supporter
I'm told I can replace the 5th gear of this box with the 5th gear from a UN1-08 box , as used in the Renault 2.5 V6 turbo, in order to give a ratio of 0.76 rather than 0.82.
Has anybody done this or have any other 5th gear swaps?
Hello Rob,
This is exactly the path I took, but I asked Chris Cole to swap the 5th gear over. Just to recap, I had the 5th gear from a R25T swapped into a R21T box. It gives 5 well spaced ratios, the 5th gear may be a little high for the racetrack, but it is superb for the long motorway runs. At 3000rpm I'm travelling at about 85mph.
Here's a couple of questions:
1. How can I be certain that my box is a Renault 21T?
2. Where does one obtain a Renault 25T fifth gear?
3. I assume it's necessary to obtain a 2-gear combination?
Alright, 3 questions!
tony normally on the rear end of the box their will be a tag which is bolted to the rear cover it should have the numbers un1-13 denoting it is a type 13 box with the 3.44 diff and 0.82 5th gear you could also count the number of teeth on diff of the box in question.hope this helps
chris cole as far as i am aware purchases the renault 5th gear direct from renault around 3-400 gbp