3 series vs NG series Renault gearboxes

[jbcollier]

The idea behind setting the preload first is to eliminate the drag of the rest of the gears and bearings from affecting your readings.  Given the preload is so low, I wouldn't worry about it, just zero preload + plus a bit.  I recently did my Lotus Seven's diff as I fit a torsen unit.  There you measure case spread.  You tighten the adjuster nuts, keeping the proper freeplay, and spread the case by 12 thou.  That's quite a bit more than what the Europa gets as its cases are so much stiffer and the bearings much larger.  All that to say, if you get slightly too much preload, it is no big deal.

The races should be a tight fit into the adjuster nuts, not a push fit.  If you feel they might be not tight enough, use retaining compound.

If you have kept it clean and covered, there is no need to wash the diff assembly.  If it dirty such that you feel it needs cleaning, disassemble it and do it properly.

[BDA]

Taking apart the diff... Oooh... I really don't want to do that. Besides replacing the self locking bolts, I'd also have to replace the planet wheel shaft retaining collar. I might be able to get those but given the dance I've had to perform just to find bearings (which I still don't have), I don't have a warm fuzzy feeling about it. I'm already starting to feel a bit overwhelmed with this project and I want to have it all together for the LOG in a little less than a month. I think I'll wipe it down with solvent and blow it dry keeping as much solvent out of the inside of the diff as possible.

When you say "retaining compound", what are you talking about? Do you mean something like Loctite 660? Wouldn't that essentially glue the bearing race to the case?

[SwiftDB4]

Do not open up the diff unless there's a really compelling reason. I have had a couple open because I mistakenly thought the longer NG3 stub axles needed to be replaced with the shorter 'Lotus' ones. Because I have a twin link suspension that's not necessary. Everything went back together OK, but I had to reuse the bolts and retaining collar.

[jbcollier]

Wait a minute, I’m full of crap.  The races are pushed by the nuts but retained in the cases.  They should be a snug fit, not a press fit.  They should NOT be loose.  No retaining compound, please.

You can absolutely reuse the ring gear bolts.  Clean them and use red loctite when reassembling.

[BDA]

No worries, JB. I explained on my "Never a Straight Line" thread in the Member's Cars forum how I got them in. They are snug so I worried in vain. I didn't use any Loctite. I elected not to take the diff apart. I had the bearings pressed on the diff carrier and then I just cleaned the outside of it and blew it dry. Everything went pretty smoothly so I'm ready to receive my pinion and primary gear bearings and start putting it back together!

Thanks for checking in Swift and JB!

[BDA]

I'm anticipating receiving the last parts to rebuild my tranny (I'm holding my breath because I want to make the LOG on Aug. 25!). Getting all the parts cleaned and laid out so hopefully the assembly will be quick and error free (it is HIGHLY unlike me to be this organized!).

Can anyone who's built a tranny tell me if I should assemble it dry or should I squirt some tranny oil on the parts first?

[SwiftDB4]

Outside of oiling the diff  and R&P the rest of the internals probably don't matter. On start up oil will quickly get thrown onto everything else. You're also not loading most of it until you put it in gear.
However if it would make you feel better oiling everything it wouldn't hurt if you can keep the RTV case surfaces oil free.

[BDA]

Thanks, Swift. That's what I thought but I wanted confirmation.

[jbcollier]

I would lightly oil any rotating part (loose gears, bearings, etc).  ESPECIALLY 5th gear.  It take time for oil to get up there and work its way in.

[BDA]

Good idea, JB! Thanks!

[BDA]

I've set the ring/pinion backlash and when setting the bearing preload, the load to turn ring gear is too much - about 8 lbs (it's supposed to be between 2.25 lbs and 6.75 lbs) even though the side opposite the ring is loose. I can wiggle the output shaft on that side a little so it's clear the bearing isn't making good contact with the outer race. I squirted some oil on those bearings (not much inside the tranny though). There is a drag such that when turning the primary shaft with the box in neutral, the secondary shaft turns too. When you hold the secondary shaft it stops turning and the primary shaft spins by itself.

Because I don't know any better, I'm thinking this is because all the synchros are new, the pinion bearing and the equivalent primary shaft roller bearing have some grease on them (for putting it together), and that everything is a little tighter now.

I'm thinking I'll tighten the adjusting nut till the outer race makes good contact with the rollers in the bearing and then tighten a little more.

Does anybody have a better suggestion?

[SwiftDB4]

After sending you a couple of PM replies I reread your post. You set backlash before preload? Preload needs to be set first, then backlash adjustment by turning one side clockwise and the other counterclockwise an equal amount until backlash is correct. 8-9 lbs. preload would be in the ballpark. In fact reading my Hewland FT200 gearbox manual some transaxles don't even give a preload spec, just tight enough so rotation effort of ring gear isn't excessive.

[BDA]

The way I thought about it is the backlash is dependent on the interface between the pinion and the ring gear. That is set by adjusting the bearing on the ring gear side - making sure that the diff is fully against that bearing. Then the preload can be set by adjusting the bearing on the other side of the diff. This doesn't change the relationship between the ring gear and the pinion so your original backlash setting is preserved so less tail chasing.

I think either way works. I have to confess that I had trouble following the manual but looking at it again, it does go through the preload instructions first and much later goes through setting the backlash procedure.

[jbcollier]

You can’t set the backlash first.  If one side is loose, then the diff carrier can rock making it impossible to set the backlash.  You set both at the same time.  Dial in zero preload with slightly excess backlash.  Then move each in sync until backlash is correct.

Check backlash in multiple places!!

Lastly, the preload spec is for when there are no other shafts, etc in the transaxle.  You are setting it up fully assembled so the preload figure will naturally be higher.

[BDA]

Thanks JB! That makes sense. I see now that I should have set the preload before I assembled the box. I would note that about five years ago you helped me with adjusting my backlash and preload and I was able to get the preload within stated limits. (http://www.lotuseuropa.org/LotusForum/index.php?topic=1960.msg18526#msg18526)

I’ll double check backlash at different places on the ring gear.