3 series vs NG series Renault gearboxes

[BDA]

Did your tranny have water in it?  That race looks pooched.  Do you still have your 365?

Sorry I missed this. No water that I’m aware of and I no longer have the 365. I think what you’re seeing is some grease I used to hold the rollers in the race to “install” the bearing onto the shaft.

That brings up a question: would it be a bad idea to use a little grease to hold the rollers in the outer race to make it easier to put the bearing on the shaft? Or would it be better to install them dry? Possible but not as easy.

[SwiftDB4]

Found the primary shaft bearing.
Renault # 7703090256
https://www.renaultgenuineparts.com/renault-7703090256-bearing-gearbox/

[jbcollier]

A little grease is just fine.  Glad to hear what looked like pitting isn’t!

[jbcollier]

PS: cleaned up, the pinion race looks fine.

[BDA]

Thanks JB. That gives me some real confort.

Congratulations, Swift! You found the last missing piece. As I said before, I've already asked Michel to find this for me so if he actually does find one, I'll take his. If not, I know where to go.

[kram350kram]

Try this stuff for tranny assembly:  Dr. Tranny Assemblee Goo #19250 by International lubricants (206) 762-5343.  I got under NAPA # 765-2615.   BAR CODE is 0 83137 19250 3

Holds heavy rollers, needle bearing, etc and then just melts away when heated under operation.

[BDA]

Thanks Kram!

[BDA]

The pinion shaft in my photo doesn't matter. It's from a box of used NG3 parts someone gave me. NG3 in the Europa is fine.
I got the pinion bearing # right off an old bearing itself. Used primary shaft bearing had no # at all.
As far as pinion shaft wear I'd go with it. Not ideal, but it should work. Trying to locate a new NG3  R&P is probably impossible.
Heck I had to grind down a wider snap ring from my used supplies because one in the trans was cracked. Renault used 2 different widths on the snap rings and they're unobtanium now.
Reusing snap rings isn't ideal either, but even Richard Winter admitted to doing it.
20,000 miles later no problems.

Woops, didn't see this either. Glad everything with your box is alright!

Michel said to use the snap rings over again, too. Mine came out ok. Hopefully they'll go back in ok. As I remember, they came in two sizes (30mm and 32mm IIRC) but I think I measured them as the same thickness. Anyway, I think I labled the position they were when they took them out so I THINK I'll be ok there.

[Richard H]

In the 46 years I've owned my Europa, it's had 336 [OEM], 395 [18GTS] and NG3-99 [Espace diesel] gearboxes.

The 336 came out at 71k miles by which time it had developed a low pitched rumble in all gears. This turned out to be the fault of a well pitted pinion bearing inner race, by comparison the one BDA photographed looks nicely run in. I replaced the bearing, not simple because the inner race needed to be ground such that it ended up with a split to relive the clamp load, tedious but the only way it was going to happen. That was 42 years ago, at the time it was replaced in the car with an almost new 395. The 336 has been doing static dry endurance in a variety of sheds and garages ever since..

The NG3 has a more precise shift quality I think because it has two selector shafts, one for fore-aft gear selection and the other to move across the gates. More travel, therefore any lost motion has less effect, selecting gears is very predictable these days, if having the feeling of 'moving some mass' in contrast to a modern shift that feels very light.

[BDA]

Very interesting, Richard! I’m curious about a couple of things:

Could you provide some details about how the inner race of your pinion bearing was ground and repaired? I assume the pits were ground out and something was applied to the surface to bring it back to the original diameter. I don’t understand about the “clamp load” or split but assume it is related to what brought the diameter back to spec. Since it has been doing “static dry endurance” since then I guess there’s no way to assess how successful that fix was…

What led you to replace the 395 with the NG3?

[jbcollier]

The three series transaxles have a separate inner race for the pinion roller bearing.  It is a VERY tight press fit and retaining compound is used a well. You have to grind a slot in order to break it free, very tricky but I’ve done a couple now with no issues.

[BDA]

I see why you suspected that mine had a separate race. I suppose it was a cost saving measure to grind a race onto the shafts. I'm puzzled why so much attention needed to be paid to the inner race not spinning on the shaft (I assume that's why the tight press fit and retaining compound) since the bearings on the other end of the shaft are "regular" double tapered roller bearings and double row ball bearings. Maybe it has something to do with the fact that the nuts on that end of the shaft help lock in the inner race??

I hadn't thought about it till now but the outer races of the output shaft bearings are not locked in the tranny halves so they can be adjusted for preload. That would seem to allow a risk that the outer race might break free and spin. How are they installed? The manual explains how to get them out (by gently taping them out with a 71mm tube or similar). Should I assume they go in the same way?

Speaking of those output shaft bearings, the manuals says to set the preload for those bearings with only the diff installed in an assembled case. Wouldn't the preload need to be readjusted after the backlash was set? Why is the preload supposed to be set before the box is build? Just to get it in the ball park?

Yeah, I know... questions... questions... questions...

[jbcollier]

It has to be super tight fit given the tremendous loads on the pinion bearing.

Had to scratch my head a bit.  What you call “output shaft bearings” are really diff carrier bearings.  The factory method is to set the preload in a position where there will be too much free play when it all assembled.  Then move each nut equally to get the free play correct.  It works, if a little involved.  I just get the free play set slightly too large (a thou or so) with zero preload and then turn one side to add preload and get the free play perfect.

The tapered roller’ race is tight into the “nuts”.  They don’t rotate.  I use an old race to drive the new ones home.  Do not drive the race out crooked.  This can distort the nut and impair the fit of the new race.  Make sure you drive it out square.  I just tap it out alternating from one side to the other.

Finally hammers and bearings are both hardened surfaces.  Hitting them together can cause chips which travel at very high speed.  Use a punch instead and wear eye protection.

[jbcollier]

Lastly, I have built a lot of diffs.  I mostly set them up by feel now.  Just go slow and don’t be afraid to back-up a bit if you’re not sure.  Diff preload is light weight in these transaxles.  Get it to zero, then add a smidge.  When rotating the ring gear you should be able to feel the difference between zero pre-load and preloaded.  Zero preload is just right when the free play in the diff carrier bearings disappears (No side to side on the ring gear).

[BDA]

You are of course correct that I was referring to the diff carrier bearings. Being the first tranny or transaxle I've ever rebuilt, I haven't gotten all the terminology and sometimes the relative orientation right. I think elsewhere I've used "hub" incorrectly... I'm learning and I appreciate your correction! 

I have set the bearing preload before (with your help - thank you again) so I pretty much know that drill but my curiosity was why did the manual say to set the preload before before installing the secondary and primary shafts. Since the ring and pinion back lash would have to be adjusted and doing that would require adjusting the finned nuts which moves the outer races and so you'll have to set the preload again. Is the reason to set the preload without the secondary shaft and pinion just to get a starting point? Also, I've noted the number of turns to take the finned nuts off each case half. Would it make sense to start there (primary and secondary shafts not installed)  rather than actually set the preload?

Thanks also for the tips for getting the old races out of the case. I already got them out and they were very easy to get out which got me wondering about how well they will stay stationary in the bores of the case. After all, if they are loose enough to move in and out, it seems like they could also rotate.

I also noted that the manual calls out using molykote grease on the sunwheel in the diff. Since I'm not rebuilding the diff, that gives me pause when I consider washing out the diff in my parts washer (that sounds silly since whatever molykote was used to assemble the diff originally would certainly have been washed off long ago with tranny oil) but I just want to make double dog sure it would be ok to clean the diff in my parts washer.