Renault UN1 transaxle, everything

Hi Bruce, no it doesn't. All primeshafts , whatever the UN1-XX versions were all helical and with the same ratios.

The only straight cut gear is the reverse. Maybe, what you consider to be the first gear is the reverse one, as it is a bit different than the earlier versions : teeth stand over a wider surface on the shaft because ont these UN1-XX versions , reverse gear is synchronized.

Best
Youre right. I did know this, but when I looked at the picture on the 'lotus' link above, you can see a very wide, straight cut gear, which from a quick glance I took it as the newly cut 1st gear you get on uprated shafts. I just went and checked a few standard shafts in my workshop and the reverse gear on a standard input shaft, the width is very small in comparison to the one in the photo, like only 13mm or so wide and that one looks almost like 30mm+ in size! Hence I thought it was the straight cut first. Interesting to notice these differences in shaft design. But I see what you mean now about the synchro reverse gear.

Just thinking, I went and had a a look in one my assembled box with uprated shaft, and there is plenty of room to have the reverse gear teeth wider as seen on the shaft in the photo link above. I did also notice, that the uprated shaft did not have the straight cut reverse gear made wider along the shaft, but cut very narrow as the earlier boxes are.

I also have this other theory, that this is also the narrowest part of the whole shaft. And having the gear teeth spread out further along the narrow part of the shaft like that, would make the shaft stronger with less flexing less about that area. Maybe that was one of Lotus's 'strengthening upgrade' ideas as well?? Bugger - I should have had mine made up like that!
 
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Hello Bruce,

Your assumption is right. These long splines add strength to the shaft. It is not reserved to Lotus gearboxes : Some late R25 V6 gearboxes are setted like this and if I remeber well the UN1-21 wich is the gearbox for the Espace V6 is also setted like this.

Late alpine too. No ideas for the venturis, I don't have the workshop manual but would be interesting to investigate.

I have the same uprated shaft (still in the box) like the one in photo, it comes from Quaiffe and is supplied by GTO. Nice piece so I do not worry about the strength. I also had a specific 3rd gear set custom cut as because the 1 & 2 ratios are different with the quaiffe one, there was a too big jump using the original UN1-3rd gear.

Neverthless, for me one very interesting point in the difference through lotus and renault un1 is the brass locker for the forks you can see on the pics taken from rear.

They used the locker from a UN5 and not the one from the UN1. I will see to use this setting for my gearbox.

The other point is already known : the bigger bearing for the secondary shaft shaft and a smaller for the prime one. My experience showed me to never have seen a standard UN1 with burst bearing while I saw a lot with the small primeshaft bearing totally burst. So here, I beleive the original setting to be better.

Best

Stephane
 
Having given up the hunt for an economical strengthened input shaft, I have reassembled the box. It has been flipped, and I now have 5 forward and 1 reverse gear. :laugh:

However, it dawns on me that the input shaft, now being under oil, only has a dinky little oil seal between the shaft and the tube around the input shaft stopping oil from travelling forward towards the clutch area.

Does this create problems, or are there already solutions?

Clive
 
Hi Clive,

Ive just inverted my Renault gearbox,but I havnt used it yet...

I got Chris Cole the main person in the Uk who works on Renault gearboxes to rebuild and invert the crownwheel on my gearbox. I know he has done this in the past, he didnt mention any problems with that oil seal. I think you should be ok.

Mick
 
Having given up the hunt for an economical strengthened input shaft, I have reassembled the box. It has been flipped, and I now have 5 forward and 1 reverse gear. :laugh:

However, it dawns on me that the input shaft, now being under oil, only has a dinky little oil seal between the shaft and the tube around the input shaft stopping oil from travelling forward towards the clutch area.

Does this create problems, or are there already solutions?

Clive
Any update on the inversion?
Thanks
 
Hi Clive,

Ive just inverted my Renault gearbox,but I havnt used it yet...

I got Chris Cole the main person in the Uk who works on Renault gearboxes to rebuild and invert the crownwheel on my gearbox. I know he has done this in the past, he didnt mention any problems with that oil seal. I think you should be ok.

Mick
For what it`s worth I inverted my Renault box back in the late 80s/early90s and it works fine.
 

Terry Oxandale

Skinny Man
Supporter
It reverses the rotation of the half-shafts. In other words, if not inverted, you'd have the drive gears become reverse gears. The same thing can be achieved by swapping sides of the ring-gear, but generally inverting the transaxle is easier.
 
Hi again, Inverting the Renault box makes it turn the wrong way so you have to turn the diff the opposite way. The exception to this is the Alpine GTA because it is rear engine, like Porsche 911 so turns the correct way in a 40 when inverted. I inverted mine when lowering the engine to fit IDAs, and driveshaft angles looked too extreme. I did articles on it years ago in the club mag plus GTD club mag later, cheers, Kev
 
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