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Glyn Harper

Gearbox woes

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So, I've had a leaky driveshaft oil seal on my '88 Esprit Turbo (Renault gearbox) for a while, but as I don't do millions of miles I've put off changing it until today. It's been leaking a bit of oil, but I didn't think that much.

I've noticed though the gearbox sounding a little 'whiney' which is why I didn't want to put it off any longer.

So today, I've popped my drivers side (RHD car) driveshaft out and caught the oil that came out... which unfortunately looks like metallic grey/gold paint. Yes, I know what that means, sadly.

I measured it, and about 3/4 litre of oil came out in total. So anyone who's popped their driveshaft out before able to guesstimate how low my oil level was? I know they are supposed to hold 3 litres when full, but obviously it won't have all come out of the driveshaft hole.

So then I try to remove the old driveshaft seal, but it's just not happening. The seal puller I've got is one with a spring loaded 'adjustable' one which keeps springing round, so that's no good. The seal is suitably damaged though that I have to get it out now or the car will probably only travel a mile without emptying all it's oil.

Assuming I do managed to get the old seal out, and fit a new one, I have a new 1 litre of the correct original Castrol TAF-X oil. Although I'm worried now 1 litre may not be enough.

Thing is, I'm going to need to get the gearbox out to get it either rebuilt or swapped, which is going to involve some driving.. I appreciate the logical thing now would just be to whip it out instead, but I don't want to do that job at the moment. I've had the gearbox out before, and I just don't want to do it at the moment.

So, if I get some Castrol Syntrax (which I read on here is the recommended replacement) will that mix with TAF-X ok? I'd rather not buy a whole 3 litres of Syntrax if I'm going to end up draining and changing it in a couple of hundred miles anyway.

Anyone else offer any other words of wisdom at this point? I'm just hoping I can get it back together really for now. I don't do millions of miles a year (probably 500 at most) so even if the gearbox is worn, I'm sure it'll keep me going till next year when I can properly plan getting it changed or repaired, either by making sure there is someone able to get the parts or alternatively source another decent gearbox in the meantime over winter.

Not a good day. I'd actually be happier if I'd managed to at least get the old seal oil out.

Cheers in advance for any advice.

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Just to add.. I’m not going to risk mixing Taf-x. As the oil that’s come out is full of metal particles, I’ll drain the whole lot and replace with new Syntrans GL4 which is the correct spec. Just ordered 3 litres. 

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Just another update. I love this thread I'm totally alone on!!

This is the swarf I took out of the oil, and also a video of the oil where you can see it looking a bit metallic.

But now a couple of people are telling me, if the oil hasn't been changed for a long time (it hasn't) then it's probably normal.

Despite the leak I've had, I took 2 and 3/4 litres out when I drained it, so it's only been 1/4 of a litre down on what it's meant to have. I'm wondering now if it's as bad as I've been worried about? Thinking I may just fit a new seal, fill it with new oil, and see how it goes? I only do 500 miles a year probably, so maybe it's not worth a rebuild at the moment.

 

Photo 15-10-2017, 4 03 08 pm.jpg

Video 15-10-2017, 5 21 24 pm.mov

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I'm no gearbox expert but I'd be surprised if that was 'normal'. That swarf means that some parts of your gearbox are now smaller than they used to be and that can't be good...

Edited by eeyoreish

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That's what I was worried about. But apparently, the way gearboxes engage, you do get more mashing together of metal than you do in a the engine. So maybe this is normal if I've not changed the oil in the gearbox for about 10 years/5000 miles?

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The swarf will also be in the (needle) bearings etc of the Gearbox. Bearings only like "clean" oil and not oil contaminated with particles. The same applies for the gears and the synchrorings.

I would open the (pandora's) gearbox.

just my (2 euro's ) thoughts.

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The whine I get from 5th only and I assumed typical for the Renault gearbox.

I asked a while back if the newer and more available Renault Traffic gearbox was a suitable alternative fit but didn't hear from the experts here.

My gut feel is that is too much metal wear.

I've seen advertised but can't recommend (as I've never tried them) alternative oils that may work better than the original specification that were available 30 years ago.

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I'm going to try some of the new Syntrax.

I think for the sake of the £40 worth of oil it's worth filling with oil, and seeing what it is like for a little while. If it becomes a problem again, then I will take the gearbox out. My thoughts are, if it is already damaged, then the parts will need replacing anyway so I may as well get some more use out of them first. The car drives fine apart from the slight whining noise. With the oil seal changed so it doesn't leak, it may do another few years before I need to worry about it properly.

It is a lot of swarf, but it's also a lot of years since it was last changed. :) In fact, on the photograph, the area the swarf is in, is only about 3cm across.

Edited by Glyn Harper

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Whoever told you that is normal is talking nonsense: the glittery dust you've recovered is the case-hardening flaking off of the gears inside, most likely due to overloading, or possibly overheating due to a lack of lubrication. This wear will accelerate. And there shouldn't be any whining noises coming from the gearbox either, which indicates another problem, possibly with the synchros.

The swarf from the case-hardening will work its way into every single part of the gearbox, which is on it's way to being completely knackered, and it's not going to heal up at any time. If you strip it now, you might save yourself from buying some more internal parts.

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Ok - here comes the advice from a full on esprit gearbox smashing expert.....

ive smashed a CWP on a v8 and the second gear dog teeth on my s4. Whatever you do from this point forward - anything other than a strip and rebuild ain't gonna fix that box. It's fooked. You may slop in some new oil - and it may last a few 1000 miles more - but you will just be delaying the inevitable. If it goes bang badly it may screw up some very much more expensive bits than are already damaged. 

If it was me - I'd whip it out and have it rebuilt. Feel free to ignore me - I have a whole pile of smashed parts I can show you though ?

It should take no more than 1.5-2 hours to remove - hardly life changing time

I'd be very much interested in what the CWP looks like and if that gearbox has been previously refurb'd - any historical info on that ??

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I'll add my 2¢ as well. You're up for a gearbox rebuild. Even if you were to ignore the case hardening flakes as Ian said, the large needle like piece is still a worry. I have no whine in fifth either.

Sorry.

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My bets - that needle piece is a section of CWP tooth - and the flakes are from the very same place. I've got one like it in the garage missing much much bigger bits 

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Cheers chaps. Yeah, I’ve resigned myself to the fact it needs to come out now and get opened up.

When it was rebuilt about 3 or 4 thousand miles ago (years are irrelevant due to how often it’s used per year!!) it was mainly syncros that were replaced. Although it was stuck in 2nd gear that time so I’m not sure what else was changed. Bit disappointed it’s gone again to be honest. My car puts out 280bhp (confirmed on a rolling road) and it’s not a V8, so the power shouldn’t be an issue.

My next dilemma is whether to rebuild this gearbox, or get another. There’s one on EBay at the moment out of an SE that would drop straight in, for £650. It’s been sat in a container for several years apparently, but apparently is fine. The guy sounds genuine.

If I got that, I would still have it opened up to check, and new gaskets fitted and maybe syncros.

may end up being cheaper to do that, than a full rebuild on mine. I don’t even know if all the bits are still available for them.

Or would it? I’ve no idea how much it would cost to gut mine. Bit wary about getting it done again. I thought the reason it had gone again was because it had a leak I’d not spotted and I’d therefore allowed it to get damaged. But when I drained the oil there was 2 3/4 litres, so although a little low, probably not enough to cause the damage it’s got.

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It's not that simple, there are at several variations of the UN1 transaxle, the early Renault boxed cars ran the UN1-016, these were replaced as the cars became more powerful with the UN1-026 (high torque box), Have a look at the rear casing of the box, there should be an aluminium tab attached to one of the cover bolts, it will be stamped UN1-016 or UN1-026.

I would suggest that, if you are going to replace it, you should look for the later UN1-026 or 028 (as used in the GT3). The power your car is making is too much for the early box. It may be necessary to change the selector and cables as they are on the other side.

B4 you remove the box, It may just be worth removing the rear cover, the 5th gear securing nut can wind down its shaft and grind away at the ally casing causing a whining noise and plenty of swarf.

FYI, the UN1-027 is the V8 box, the gearing wouldn't suit the 4 cylinder engines.

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The GT3 gearbox has a different CWP ratio, and not recommended for the 2.2 litre engine.

The  V8 box has a slightly higher 5th gear ratio.

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1 hour ago, ian29gte said:

The GT3 gearbox has a different CWP ratio, and not recommended for the 2.2 litre engine.

The  V8 box has a slightly higher 5th gear ratio.

Just found the 5th gear info - V8 has 0.76, 4-cyl has 0.82. I reckon the S4s would pull that higher V8 5th, but not sure.

I also read that the GT3 'box has a different 3rd gear to the 26 and the 28.

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Unfortunately there aren’t millions of UN1 26 boxes available it seems, unless I leave my car without a gearbox for the next year or two.

I’m down to getting another UN1 16 gearbox that’s on eBay, or repairing my own.

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Is it possible to get the stronger parts into a UN16? I need to repair mine really. I can’t really be swapping all the gearchange mechanisms over as well. Before I know it the car will be off the road for about 3 years and other parts will stop working.

bit depressed about the whole thing to be honest. Just been told it’ll be £1500 plus vat to overhaul my gearbox, and that I should be wary of gearboxes that have been in storage.

dont know why, or whether it’s just a line. I just know whatever happens it’s a nightmare and I haven’t got a bottomless pit of money. I’m on the Isle of Man so I can’t go to any other places to overhaul the gearbox. 

Edited by Glyn Harper

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UN1


> The initial Lotus unit - UN1-016 had a Torque Limit set at 315 Nm (232 lb.ft).
This Version used different Crown Wheel & Pinion Material compared to most other Renault Applications (except Alpine, which had a different direction of rotation). Differential also had 4 Pinions like the Alpine & some of the Agriculture Units
(UN1-023 and UN1-024).The Lotus Version also had extra Dowels in the bell housing joint to further control bending.


>The UN1-026 (known as the High Torque Box) had new Casings which were stronger to reduce Bending under the increased Torque. The Main Fixing Bolt Size & Torque was also increased. There were some revised bearings and retaining plates introduced at that time. The Torque Limit was increased to 400 Nm (295 lb.ft)

> When the V8 came along (UN1-027), it carried over all the 026 features. Plus, there were also updates to the shaft machining & gear assembly procedures as well as well as the revised 5th gear ratio, synchro was added on reverse.

> For the GT3 (UN1-028) we changed 3rd gear the Final Drive Ratio to suit the Engine Performance. This revised Final Drive Ratio came with a lower Renault torque limit of 300 Nm (220 lb.ft).

The Gearboxes had to use a specific lubricant to eliminate Severe Crown Wheel & Pinion wear (Mobil SHC-630M... no longer produced, or Castrol TAF-X... also recently discontinued by Castrol).This was introduced during the initial development testing. The standard Renault lubricant (Elf Trans elf TRX) did not give enough protection due to the Load and Heat produced by the rapid Esprit Turbo Engine Torque rise.

> At all times the gear ratios used in the Lotus application were standard Renault, but the Lotus Crown Wheel and Pinion used upgraded materials. The Renault CWP parts will fit, but they're not as strong.
The main problem was in the stiffness of the Transmission Casing and the loading on the Crown Wheel & Pinion. The Lotus versions of the Renault UN1 Transaxles are the strongest variants available. The only thing that comes close is the later Renault Alpine GTA UN1-019, but it has a different direction of rotation and different final drive Ratio.
> The UN1-013 from the Renault 21 Turbo would provide some of the gears (not 3rd, 5th or final drive) and synchros suitable for the GT3.


An original Esprit Renault UN1-016 is standard in the non-SE and the SE.
The high-torque box started in 1993... 1993.5 SE and the S4 in Oct 93.
Just by looking, the shift translator is on the left side, and there should be an ID tag, or stamping, on the gearbox.

Esprit Original .... UN1-016 ... Started with first Renault equipped Esprits
... 1988 DOM / ROW intro
... 1989 Federal intro, non-ChargeCooled, and SE.
... With 0.8205 5th gear ratio (0.8205 x 3.89 final = 3.1917:1 overall). Left side shift translator, 315 Nm (232 lb.ft) torque rating
Esprit Hi-Tork ... UN1-026 ... 1993 intro (1993.5 SE and the S4 in Oct 93)
... Stronger case with new castings
... RIGHT side shift translator
... 400 Nm (295 lb.ft) torque rating

Esprit V8 ....... UN1-027 ... 1996 intro, for the most part carried over 026 features
... V8 bell housing - does not share 4-cyl bolt pattern
... Higher 5th ratio (0.76)(0.76 x 3.89 = 2.9564:1 overall)
... Synchro-ed reverse
... LEFT side shift translator
... 1998, modified cross shaft for DIRECT CABLE shifter, no translator.
... Minor durability improvements w/ Sport 350 intro.
... 400 Nm (295 lb.ft) torque rating

Esprit GT3 ......... UN1-028 ... 1998, for the most part like 027
... With lower third & final drive ratios (1.41 & 4.11 ??)
... With higher 5th gear ratio (.076)(0.76 x 4.11 = 3.1236:1 overall)
... 4.11 CWP ratio not suitable for torque of 910 or V8
... CWP is Renault parts, not as strong as Lotus 3.89 CWP
... 300 Nm (220 lb.ft) torque rating due to a weaker CWP

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My car made 326lb of torque on the rolling road recently.. so basically the UN1-16 is useless and not worth rebuilding. And even the UN1-26 (which I can't find any anywhere and would need a whole load of extra gear selector parts) isn't really up to it either.

I'm knackered then basically. I may as well break the car and sell it as parts, or spend about 6 grand that I don't have.

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Want me to send a trailer ??? Save you the hassle 

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Sorry all, just a bit depressed about the whole thing today.. no good news really.

I just spoke to the guy that rebuilt my gearbox last time, and I do indeed remember he's moved buildings from when he last did it.. which was 16 years ago!! So in actual fact, I think it was more like 17 years ago it was last done. Time flies.

He spoke a lot of sense though. We discussed the amount of miles I do, and did back then, and it was certainly more when I first got it than these days. He said (and it's a good lesson to everyone) that not using them really does hurt them as the oil runs off all the gears and you get condensation building up on the shafts and the gears. He said every few weeks they should just be run for 4 or 5 minutes, the gears selected to make sure the shafts are lubricated, and they should last a lot longer.

I've only been using mine a few times a year for the last 10 or 12 years, so it's probably not surprising it's gone bad.

The extra torque I have probably isn't as much of a problem, as I just don't thrash it, track it or anything like that. I know they were built to be driven hard, but I do drive it nicely. Quick, but not like an idiot. I don't do wheel spins or dump the clutch or anything like that.

So, I'm just tempted to get this one rebuilt again as it was 17 years ago, and hopefully I'll get another 17 years out of it.. I'll certainly be doing less miles than I did when I first had it rebuilt.

Puts the state of the oil into perspective as well.. it's 17 years worth of oil and swarf that came out when I drained it.

I think the lesson here, is to change your gear oil every couple of years, and start the car and run it when it's sat in storage.

Just hope he can still get hold of the correct crown wheel and pinion, which Is the most critical part I gather.

I'll leave the power as is I reckon. It may not last 60,000 miles.. but if it lasts 6,000 miles, that's about 15 years with the usage it gets.

I'll keep an eye out for a UN1-26, which may come up in a few years time if I'm lucky, then think about swapping it at that point. Otherwise I really am going to go nowhere.

Edited by Glyn Harper

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