Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: Stuleslie on Sunday,May 06, 2018, 07:32:10 AM
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I changed both output oil seals on a NG1 gearbox on my 72TC. N/s seal is ok but I have had the o/s seal off four times in trying to cure the leak. It is not just an odd drop but I estimate I lose 250ml every 50 miles. In the pic. there is a drip on the drain plug and a small pool of oil at the bottom edge of the castellated nut after a rest drive of 10 miles.
1. I have shimmed the drive shaft and there is no play there, the roll pin is very tight.
2. I have added sealer around the o-ring at the base of the gearbox splines
3. I have fitted a 35mm internal diameter seal instead of the nominal 36mm hoping that would seal better.
4. I have checked that the spacer between the inner bearing and the shims/driveshaft that covers the o-ring and makes a seal with the oil seal is not oval, measured to within 0.01mm.
The only thing I have found is that I can move the splined output shaft sideways by a few thou. Is this enough to lose so much oil? Has anyone any idea if there can be any play in the gearbox output bearing?
Any advise would be appreciated as I any going bonkers :headbanger:
Thanks Stuart
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Did you seal the threads on the seal/bearing carrier. I couldnt see the pic. Use a non setting sealant on the thread such as blue hylomar
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No I haven't tried that, I'll give it a go, Thanks
Sorry the pic did not download, here are new ones.
It looks like there is no oil coming through the splines. I just can't understand how so much oil can be leaking so quickly.
I checked the air breather thinking there might be pressure in the box but it was ok.
Stuart
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It's a bit of a bodge up to allow the shafts to be load bearing.
How are you fitting the seals? They have to be fitted from the inside of the diff nut.
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Yes done that JB, several times.
The left side is OK and was treated in the same way.
I wonder if there is movement from the diff when driven. I cannot feel any play at the shims or the U/Js or the wheel bearing.
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The seal-nuts set the position and preload of the differential. Any chance it is a bit loose and the diff (and output shafts) able to move around?
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I cannot tighten the nut past the mark I made at the beginning of this work but that is not to say it is in the right place. The history of the box is that I only ran it a few hundred miles before I striped the car and then it has sat for the best part of 15 years idle. The problem has only shown itself since I have had the car back on the road. It could mean the leak has always been there. I think it might be time for a strip-down.
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Looking at the pics it looks like the oil is pooling out of the threaded seal holder. It will leak from their if not sealed. And it will pour out I know as when I built my box I didn’t seal the thread.
As long as you put the seal holder back to where it was you should be ok but these seal carriers control the diff bearing clearance and the diff backlash. The manual goes into a lot of details on setting this up and it has to be done with the gearbox out and the bell housing removed to check the backlash.
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Took the seal out again today. Checked seal position, checked the inner spacer for roundness. On re-assembly, I sealed under the spacer around the o-ring and the nut threads. Result....just the same!
Buzzer, there is also a pool of oil at the bottom of the seal lip that touches the driveshafts. The leak must be around the turning shaft.
I spoke to Richard at Banks and he said he has another solution which will take a couple of weeks to get hold of, so I’m waiting with bated breath.
I will let you know what happens in a few weeks.
Thanks very much for everyone’s input.
Stuart
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Ok so definately looks like the seal. I think I actually have a leaking seal at the moment, but as I’m just getting it on the road I will bed it in and monitor for other leaks etc and address them later. I also had a leak on the selector seal which on the 365 is low down. I seam to have fixed that but bizarrely I am getting leak above that seal now near the mountings at the rear.
Be interesting on Richards fix. A tighter seal?
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No doubt its the plug which has the 5th gear detent ball and spring behind it. You will need to remove it and seal with silicone if the aluminum sealing washer isn't doing its job. Its a coarse thread, so needs torque to seal but with the slotted screwdriver its hard to get torque. I've always sealed with silicone to get it leak free.
Jerry Rude
4005R
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Yes that was my thought but just assembled it with blue hyloma so May have not sealed it properly. I’ll monitor and confirm.
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It was suggested to me that the leakage problem might lie with the o-ring behind the spacer at the bottom of the splines on the output shaft. After measuring I bought an o-ring 21mm id x 29mm od x 4mm thick. this caused the spacer to sit proud of the bearing but when the drive shaft, shims (same number of shims) and roll pin was inserted I think a good fit was made. The result.........no difference!
I then received the 'good' seal from Richard which turned out to be exactly like the Renault original complete with castellated nut. I think he got the nut machined up locally. See picture of new Renault seal with the original (below) I took off in the first instance. You will see it includes a metal shell and felt washer.
The distance the seal is pressed into the nut is critical so that the seal lip rides the flat portion of the inner spacer. I measured everything and concluded that the metal shell of the seal on the new part should be pressed 2.5mm into the nut (from the back, if you know what I mean?). I went to the trouble of making a 2.5mm spacer so that the distance was correct and that the seal was square. All back together and road tested, the result......no difference!
You should see in the other pic. a pool of oil on the threads of the nut but the felt washer is also wet with oil. The amount of leakage I'm experiencing cannot be coming from the thread and must be coming from the seal lip. I can only conclude that there are some forces pulling the shaft laterally, particularly on cornering, to cause the seal to leak. This makes me think there is something wrong inside the Diff. Remember this gearbox has not been run for many miles since bought and could have had this problem from the beginning. Having said that why is the other side not leaking?
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When you received the banks kit did you ring him to talk you through it? I can't fully rammer but I'm fairly sure I had to change part of the seal before fitting it which I would not have know if I hadn't rung him.
Sorry that is vague.
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Hi Gary, yes I’ve been talking to Richard throughout this episode and he has not mentioned taking the seal apart. The main point is making sure the seal lip is rubbing on the inner spacer. The measurement is a bit tricky as a reference point is difficult to maintain. But there is at least 6mm to play with so I am sure I am putting it in the right place.
The latest line of thought from Richard is that the bearing may not be fully seated and that under stress it might move up/down, front/back and thus open the seal. I feel the amount of oil loss must be due to something causing the seal to move off the inner spacer.
I will be taking the gearbox out and removing the bell housing to check for backlash on the crown gear and check the position of the bearings. Watch this space :confused:
Stuart
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Hi Stuart,
I just had my box apart, changing it for a newer one. From your pictures, at least of the new banks nut and seal set, the seal appears to be in too far? It may not be where you ended up with, but note that the outer seal is a dirt seal, and it rides on the inner part of the yoke. The inner seal rides on the center of the spacer.
Also, how are you setting the axle/yoke shims? are you getting the assembly tight so the yoke cannot shear off the roll pin? I usually shim them so the pin drives in just a little harder than with no spacers so I know it isn't allowing any play and the yoke is tight against the spacer and won't damage the pin.
Also, when I disassembled this newer 365 box, it had the bottom of the nuts and the o-rings siliconed in. It had only 18k miles on it so either it was a virgin or had been sealed up by a dealer. Either way, I too used a 1/8 silicone bead around the outer, back of the bearing race, against the inner threads of the housing, and screwed in the nut into the silicone. Then used a small amount on the axle groove where the o-ring will sit, sliding the o-ring onto the axle, and then a small amount on the inner lip of the spacer where the o-ring sets. I was able to press the spacer on by hand up against the bearing. I let the assembly sit overnight and installed the axles, etc. the next day. So far, knock on wood, it hasn't leaked a drop in 300 miles. I tried the loctite thread sealant, but had such a time removing the nuts the next time I vowed to try something different.
Jerry Rude
4005R
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Hi Jerry, yes your right the new nut and seal in the top left of picture from Banks is too far in. This is how it comes, the back edge of the seal is flush with the back of the nut. After extensive measuring I pressed the seal into the nut by 2.5 mm.
I have ensured the axle/yolk is shimmed up tight.
I will look into using the sealer as you mentioned when I reassemble the box.
The strange thing is that I have had no trouble with the left hand side, it has been perfect since I changed the seal.
Stuart
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Problem solved :trophy:
I’ve got a dirty big b&*#;y hole in the casing!
I had to take the gearbox out to see if there was something wrong with the diff bearings. I took the bellhousing off and as I was looking at the bearing and saw light through the hole above the righthand bearing in pic 1. It turns out to be a hole for a speedo inductive sensor which senses the dog toothed gear attached to the diff casing in pic2. Evidently it is quite rare and is usually blocked off. There are many holes in the box casing but they are all blind ended (except my one). I plugged the hole with a 3D printed bung with a screw flange. Pic 3
Perhaps I should get the dummy award of the month but unless you take the bellhousing off you would never know that the hole was not blanked off.
FYI I made a bracket under the balance point of the gearbox and attached it by four M8 bolts into the box and bolted the bracket to my trolley jack. I could then pump up the box level to the engine and push it into the clutch plate single handed in pic 4 (sorry slightly out of focus)
Road test perfect, not a drip, I’m a happy bunny. :BEER3:
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I wouldn't feel too badly about it, Stuleslie. It's not something you would expect and a quick look through the NG manual, I didn't notice anything about it. I've certainly been caught by a lot more obvious stuff than that, but admittedly, that is a low bar.
I'm glad you finally solved the problem and everything is working!
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Well, what may have seemed dire a couple of days ago is now a simple issue with a straight forward fix. Sounds like a win to me. Glad you got to the bottom of things.
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Thanks Guys for all you help and sympathy :))
I wonder how many gearboxes like mine are out there. The tag label states it was a NG1 but when you look at the diff. it has four planar gears like a NG3 box. :confused:
Stuart
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On the subject of leaking output shafts....
What size are the original O-rings?
There is mention of 21mm id x 29mm od x 4mm thick earlier in the thread, but that appears to have been a best efforts guess.
Thanks in advance :)
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Hi Stephan, that is exactly the size I fitted in my box. The 4mm thickness does require a bit of compression to lineup the roll pin holes. It was not difficult with the chassis on stands I just just slowly jacked up the wheel and the holes aligned. There is a company in the UK that can supply o-rings in any combination of id, od, and thickness at minimal quantities, so if you need their address I can look them up for you.
Stuart
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Thanks, I've got some that should be close enough so saves going looking for more.
Anyone got strong feelings on using/not using a smear of additional sealant on the spacer or splines?
At this stage I'm not planning to, but it's been mentioned to me by the local Alpine guy.
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If everything is super clean, it won't hurt. Don't use a sealer that sets otherwise it will be heck if you have to get the spacer out again.
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I chose to keep clear of sealant for now as it isn't a big job to pull the shafts and add if required.
Only had short 1 heat cycle/run but no leaking so far.
Have I mentioned how much I dislike changing uni joints?
Not the assembly, it's the removing the old ones that bugs me ;-)
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I think I can match the diversity of the gearbox oil leak through the driveshafts described above.
I bought 4376R and 4688R in pieces in a 40ft container via a dealer in Chicago who died, the whole lot went to a dealer in Houston, who also died, his widow sold them to an enthusiast in Louisiana who decided it was beyond him, so 4376R, 4688R and a whole load of other stuff, the good, the bad, and the ugly, was shipped in a 40ft container via New Orleans and Southampton to me.
I have completed 4688R which I am keeping, and I am finishing off 4376R at the moment. I put the gearbox in, drained and filled it with oil, and oil poured out of the diff output holes, both sides.
I thought putting the driveshafts in would cure the leak so set about getting the shaft splines lined up to bash in the roll pins. I check the holes are lined up with a 5mm drill. If that goes through and there is no inward play when I take the drill out, I know the shimming is correct.
The shimming was awful, so I went on eBay and bought loads of shims. £3.69 for 10. Cheap. I will have 10 in all the sizes please.
The shims arrived, and it was time to add more shims to get the play out before driving in the roll pins.
I thought I would see how big the gap was by undoing the big castellated ring thingy, and it was f'ing huge. 10mm. Something is wrong, all I could see was a rubber O ring.
I then undid the castellated ring thingy on another gearbox and saw a splined spacer covering the O ring. This spacer was missing on both sides on the gearbox which fitted 4376R.
Luckily the container came with a spare 4 speed gearbox, so I went to get the spacers out by undoing the castellated rings. They were f'ing tight. I have the special tool from Banks for undoing them, a 1 1/16" ring spanner to put on the end , a big hammer, so I started undoing the ring thingies. After about 1/2 a turn, they are normally easy to undo. This one was very tight, I put heaps of pressure on the ring spanner, bashed the spanner with the big 2kg hammer, and "Ouch". The spanner fell off and my head went straight down on the the selector rod on the end of the gearbox, and then my head started leaking. "Ouch" was not enough, time to go and clean up the wound.
I stopped the bleeding by pressure on toilet tissue on the wound. I summoned the courage to look in the mirror, took the tissue off and there is a Mercedes 3 spoke star right between my eyes. I looks like some sniper has assassinated me. Time to fit an Elastoplast.
Anyway, I removed all the shims, fitted one splined spacer, mastic on the ring thingy, tighten to the same place marked with a dot from a centre punch, fit the lock tab, line up the splines and the holes in the driveshaft, and with zero shims, the holes align exactly. Drive in the roll pin, and all looks fine.
So the oil leaking out from the diff output shafts was because the 10mm splined spacer was missing so the oil seal in the castellated ring thingy had nothing the seal against.
Tomorrow, the other side.
I now have to go down the pub with a plaster on my forehead right between my eyes. That will take some explaining. Taliban assassination attempt maybe.
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I had to laugh when you said "your head was leaking".....been there done that unfortunately ... :o (leaking body parts)
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Thanks for the laugh. Hope you can fix the leak. I am glad I have a red car. It hides all the leaking I have done.
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Thanks for the laugh. Hope you can fix the leak. I am glad I have a red car. It hides all the leaking I have done.
Head leaked in the pub. Landlord gave me a blue Elastoplast. Do they make plasters with targets on? I feel like a target yet to be hit with the blue plaster central just above my eyebrows.
I won't know about the gearbox oil leak until the car is driveable in about 3 weeks.