Renault UN1 output shaft issue

Hello,

I’m after a bit of gearbox advice...

I have a UN1-13 that I had rebuilt by Chris Cole a good few years ago, in fact it was the first bit of my car that I bought. I actually finished the car and started driving it last year and have only done about 1500 miles but I’ve developed an issue.

Recently I’ve noticed a knocking coming from the rear when coasting along, it seems to disappear under acceleration and breaking though.
I found a loose rod end which was definitely an issue but it turns out not the reason for the knocking though.

So after further investigation I have found significant play in the output shafts which is noticeable through the drive shaft adaptors as per the videos attached.

can anyone shed any light on the issue that I have as something is clearly not right?

I’ve started stripping down the drivers side and will do the other side tomorrow but suspect I’ll end up removing the box, that said I would really like some guidance before jumping in feet first.

(Prob should say, I have removed the locking tab for the large castellated nut, it was on there until today)

Regards
 
Hi Paul,
looking at the videos, you shouldn't have any movement there and it looks like diff bearings are lacking the correct amount of pre-load. Personally I'd have the gearbox out & stripped to minimise any further damage
Regards,
Andy
 
thank you.

That was my thought, it’s all very frustrating as it was rebuilt only 1500 miles ago but obviously we’ll past any warranty period as the build took bloody years...
 

Shaun

Supporter
Hi Paul, mine have nowhere near that amount of play even when the oil O rings were missing, as andy says its best get that sorted it won't go away
Cheers
 
i have seen play there before when the splines have some wear on them - drain the oil and then pull the adaptors, see if the diff is actually moving as it definately shouldn't.
 
Thanks all,

I’ll get the box out and see what I can do. I suspect the preload has not been set or set incorrectly but I may be wrong, we’ll see...
 
Ok so it’s apart now, fortunately from what I can see it would appear the issue is that the preload was not set by Chris Cole when it was “rebuilt”. There was as expected significant play on the diff bearings, I don’t believe this is something that can have changed over the 1500 miles as the castleated nut was locked into position.

Typical in that the only part of the car that I did not build myself is the bit that fails, as they say if you want a job done properly, do it yourself...

So onwards and upwards I now need to rebuild the box.

After reading up it seems that to set the preload the diff has to not be connected to the rest of the gears, question number one is can I just remove the lower shaft and gears without stripping the whole box or does it all need to come out?? It looks like it may come out but don’t want to balls it up...

Secondly I don’t currently have an LSD so this is obviously the time to fit one, that said however I can’t really afford one (so my wife says) at the moment but in reality this is my one opportunity to fit one, so talk to me, do I need one, will it make a big difference, will I notice the difference??

Finally (for now) does anyone know where I can get the tool for setting the preload nut or even better have one I could borrow?

Appreciate your help
 

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Shaun

Supporter
Ouch.....I have a LSD on mine but cannot comment as its still very much in build as you know. Sure there will be comment on here, as you say good time to do it but they are not cheap, still no foreign holidays for a while so treat yourself!!
I did read on the web someone made a tool using an other castellated nut and used that with studs tapped into it the tighten the one in the box.
 
The Quaife ATB type LSD diff makes your box capable to handle more engine torque as it always even out the engine torque over both wheels. Less stress over just one wheel side drive line and so on internal in the tranny.
So if you have the change to do it as your transaxle is already open its now time to do it.
 
The Quaife ATB type LSD diff makes your box capable to handle more engine torque as it always even out the engine torque over both wheels. Less stress over just one wheel side drive line and so on internal in the tranny.
So if you have the change to do it as your transaxle is already open its now time to do it.
Bloody hell it perfectly sensible advice like this that is going to get me a divorce....

Thank you (I think) ;)
 
Ouch.....I have a LSD on mine but cannot comment as its still very much in build as you know. Sure there will be comment on here, as you say good time to do it but they are not cheap, still no foreign holidays for a while so treat yourself!!
I did read on the web someone made a tool using an other castellated nut and used that with studs tapped into it the tighten the one in the box.
Thank Shaun but I suspect a spare nut is harder to find than the tool it’s self...
 

Howard Jones

Supporter
I put a Quaife in my R21 when I had the one-piece input shaft upgrade done. It absolutely transformed the car. I consider installing a TBD diff to be the most practical and essential upgrade that can be done to a GT40 after good tires. Do it now, She will get over it. The car will always be better forever. Do it! Do it!
 
This is what the tool looks like. Mine only just arrived 1 month ago and I ordered it before Xmas 2020. Took a long time to get to me in NZ from EU (seller blamed due to covid-19 items are taking a long time)
 

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Davidmgbv8

Supporter
Well there’s no going back now...
Better to ask for forgiveness than ask permission! Chapter 3, verse 1 of the marriage hand book I failed to receive in marriage 1,2. My girlfriend has gone with me to look at 3 original 40’s, Studebaker, Gilmore, Arburn Cord Dusenberg, Indy museums, and is encouraging the building of a 40. She has a new Mini Cooper S she rarely drives under 90mph. I love her. We have agreed not to marry so we can keep enjoying our car hobby.
 
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