UN1 Rebuild

LastPago · 02-01-09, 12:32 PM

Hi,

I finally decided to start my UN1-13 rebuild.

I got it from a R21 turbo 2L 1988-1989.The price was good (225 euros) and the gearbox didn't look too bad when I was under the car in the junkyard working to remove it.

Let's have a look.

(BTW, I am french so excuse my poor english and my lack of vocabulary for mechanicals words.)

Here it is :

LastPago · 02-01-09, 12:37 PM

A broken teeth indicates that the box has been previously opened- might be a good or bad news - I think bad as a broken teeth means that the guy that has done this work didn't had the right tools....

I marked the nut with the box, unsrewed the locker, and (using the right tool) loosen the nut.

LastPago · 02-01-09, 12:50 PM

Oil and water newer mix.... this rusted colour indicates that water entered in the box...normal I gave it a karcher wash few weeks ago.

So next move is to remove the bellhousing, not difficult, just few bolts to remove. The crown looks ok , no rust. Then, I removed the tube over the primeshaft.

Then, let's go at the back of the box, remove the sleeve that maintain the arm and unscrew the allen (take care of the screw and spring). The ball remains inside, I will get it later.

So, remove all bolts retaining the back side and remove the back (it comes easily).

LastPago · 02-01-09, 12:59 PM

Using an extractor, then I removed the fifth gear.

Then , just engage 2 gears (rear and drive) to block the shafts to allow the bolts for primeshaft and secondary shaft to be removed.

Then, unscrew the 3 bolts around the pinion on the secondary. It is important, not doing it will not allow to separate the housings.

Then unbolt all bolts from both side of the housings (do not forget the 4 big ones that came across the housings) and separate the housings.

Ok this sounds nice, the box is opened. I removed the reverse shaft.

Now it is time for a big cleaning of the housings and shafts to be in position to begin the serious work.

To be continued

Ian Anderson · 02-01-09, 04:02 PM

Great step by step guide on how to work on a UNi

I'm not sure I would have the confidence to do the same

Ian

Tobias · 02-01-09, 05:08 PM

great thread.... I wan´t to see more!!!

Phil · 02-01-09, 05:41 PM

Good thread, keep up the photos. I think your English is fine, and if thats any measure the rebuild should come out O.K. too.
Cheers
Phil

skeleton · 02-05-09, 04:20 AM

very cool, keep on going

LastPago · 02-06-09, 11:53 AM

To go on...

Done some cleaning to the housings, a lot of dirt and old grease removed.

Some superficial rust because metal was hardly cleaned, nothing of importance.

Work on this housing :

Cleaned all axles and forks,
Replaced locking balls and springs by new ones,
Replaced gear selector washer.

How to do :

Remove the reverse gear contactor, remove the sleeve of the 3/4 fork and remove the fork, then pull the axle out.

Be carefull to the locking balls that will came out, use a magnet finger to take the locking ball.

Remove the sleeves of the 1/2 fork, then pull the axle out.

Unscrew the screw of the reverse gear selector the remove it.

LastPago · 02-06-09, 12:01 PM

Then,

Using a tool to be stolen to your dentist (a good reason to give him a visit), remove the springs of the locking balls.

Give a good cleaning to the axles and fork.

With a soft file, gently adjust the forks and selectors side to remove any diseases.

Remove the magnet to have it cleaned.

Give a final clean to the housings, dry it carefully and spray some WD40.

LastPago · 02-06-09, 12:11 PM

So,

Engage the reverse gear axle, place the selctor with a new washer.

Place the new spring of 1/2 the axle, place a new locking ball, push down the locking ball and push the axle to put him in place.

Do the same for the 3/4 axle : new spring, new locking ball.

Put all sleeves in place with a special attention to the sleeves that come on the 1/2 axle. The head of the sleeve MUST not be higher than the thickness of the spring. Not doing so will make your sleeve to touch the pinion teeth.

Don't forget to place the magnet.

The reverse selector screw must be coated with loctite and screwed with a 3 nm torque.

To be continued.

Ps : If I am posting too much pics, let me know.

Cheers

Stephane

Murray Cowley · 02-06-09, 01:43 PM

Stephane,
this is an excellent blow by blow account of the rebuild, very informative and I am saving all the pictures to help me with a possible rebuild of my spare gearbox. Cannot have too many pictures. Well done and thank you.

Iron Sheik · 02-06-09, 07:20 PM

VIV LA FRANCE!!!!

Excellent!!!!!

skeleton · 02-07-09, 01:42 AM

This looks great. Too many pictures, are you nuts man ? more more more ;-)

Question, do you have a list of replacement parts? I know every gearbox needs different care as they have undergone different usage and wear-out, but can you provide us a list of things always to replace?
This would be a great help while shopping around for the parts

LastPago · 02-07-09, 07:50 AM

Carlos,

I have a permanent access to renault references. I will try to edit screencaptures or will export them in an excel sheet. For sure, it is better to have the renault references of the parts needed if you want to stay in a friendly relation with your local renault shop : they don't like to spend hours to find what could be the reference of a locking ball wich will be invoiced few cents...

But the parts to be replaced may change from a gearbox to an other, it all depends of the work you want to be done : Repairing, refurbishing or rebuilding.

In my case, I am doing a full rebuild for this one, this will include changing all bearings and syncromesh for example. BTW, this is why, on the last pic I posted, you see a big hole in the housing, (I removed the differential locking bolt) as I have no more use to keep track of the previous settings : New bearings mean new settings.

Maybe the good way would be to realize a full renault UN excel with all references and maybe parts description as some can be sourced elsewhere with better prices.

Cheers

Stephane

LastPago · 02-07-09, 12:45 PM

Done some work on the rear housing :

Cleaned the cast,
Changed spring
Changed shells
Changed O Ring seals
Changed lip seal

It may sound easy and quick, in fact it is not...

How to do :

Unscrew the rear gear unlocking cable, pull the rocker. It would come not easily, if you don't succeed by hand, you can softly tap on its axle from the back of the housing.

The rocker axle has 2 O rings that need to be changed.

Then chase the selector's sleeve.

Using a metal fork, compress the spring and remove every half shell (4).

Then pull out the selector shaft.

Be carefull to the rubber boot, it costs 50 eur...Renault really sucks on this...

Remove the lip seal (selector shaft).

The housing is now ready for a final cleaning bath.

Dry it carefully.

On pic 53, these are the parts that need to be chnaged on the selector shaft.

Place the spring and the selector and engage the shaft (do not forget the rubber boot). Oil the back of the shells, compress the spring using the fork and place all shells one by one.

Place the big sleeve then place a second one in the big one.

Change the O rings on the rocker shaft.

Oil the shaft and oil the guide tubes (not sure of the name...:-(....

Oil the selector shaft.

Fill the sputting tube with oil and press on it, oil must get out and must be clean, fill in and press i until oil gets out really clean.

Place a new ring at the back of the rocker shaft.

To be continued.

Cheers

Stephane

LastPago · 02-12-09, 02:30 AM

Hello,

Didn't had too much time to post...Sorry.

Now, dismantling the secondary shaft.

How to do :

Using a press remove the 5th gear pinion.

Remove the big roller bearing, it would come by hand but the use of an extractor tool can be of help (I had to do).

Then remove the big wheel (it comes by hand) and it is the 1st gear pinion.

Then remove its synchro (comes by hand too).

Place a mark on the 2 parts of the hub to allow it to be replaced in the same position and remove it.

Then remove the locking clip. The tool I use on the pic is not the correct one, there is a special tool for this kind of clip but at the pics moment, I was unable to find it in my drawers....I will try to post a pic of the correct tool.

Place the shaft on its second gear pinion and apply pressure on the shaft (do not forget to protect the shaft). If you use a bigger press, place an horizontal extractor under the second gear pinion instead of a direct contact to press support.

Pics :

LastPago · 02-12-09, 02:45 AM

Now the primary shaft.

Remove the sleeve of the motion shaft.

Then separate them...some rust here...

Remove the seal.

Remove the locking clip (using the right tool not this one, see previous post).

Place a support under the 4th gear pinion (just under the big teeth not the little ones) and apply pressure on the shaft.

Then remove the synchro (comes by hand),

Mark the 2 parts of the hub to allow them to be replaced in the same position, then remove it (comes by hand too).

Remove the spring with the cylinders (3). I am sorry I don't know the name of this part in english...

Remove the washer (comes by hand),

Remove the locking clip,

Remove the hub internal (don't know the name in english too

)

Remove the synchro

Remove the 3rd gear pinion,

Place the shaft in the press and remove the roller bearing on the reard side of the shaft.

Ok, now its time to wash all these parts and to make a diagnose.

To be continued

Pics :

LastPago · 02-12-09, 02:53 AM

To allow a better understanding of the dismantling sequences, please find attached a drawing view of the shafts.

LastPago · 02-12-09, 03:27 PM

Just wanted to calculate what was the impact of fitting a 0.76 ratio 5th gear instead of the original 0.82.

In a theorical world, this would allow an 8.5% increase for max speed and a 8.5% torque decrease (5th gear) wich seems to be good as the weakness of the UN1 is the primary shaft 5th gear side...no talking about the speed increase....

I post my calculations.

Cheers

Stephane