Lotus Elan

Diff pinion oil seal

PostPost by: Geoffers71 » Sat Aug 06, 2016 10:57 am

I'm trying to pluck up the enthusiasm to replace the pinion oil seal in the nose of the rear axle. It's been leaking more or less since I finished the rebuild, but I left it as I hoped it might seal itself up once the car was in use again. Faint but useless hope! :roll: I think it's getting worse :evil: I just want to confirm how I think it goes before biting the bullet and crawling underneath. So...
1. undo the rear of the prop shaft and swing out of the way
2. Remove flange by undoing the retaining nut, remembering to mark it's position so that it can be tightened back to the same tension. Is this nut captive or peened over in some way?
3. Hook out the deflector dust seal and the seal itself. This sounds easy enough, but I suspect it isn't. Any tips as to the best way to do this?
4. Re-assemble in reverse order with new seal.

It's not going to be this easy I'm sure, I've worked on Lotus' for too long to believe that. What problems am I likely to encounter. Eg. How difficult is it to remove the flange once the nut is off? Is there a danger of pulling the pinion out of engagement? If so, what to do about it? Is there any need to replace anything else, eg the collapsible spacer, or the bearing, or can I get away with just the dust and oil seal?
The more I'm talking about it the more my enthusiasm for the task is dwindling away. Any helpful hints and tips very gratefully received, ...and a dollop of enthusiasm wouldn't go amiss! :D
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
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PostPost by: RichC » Sat Aug 06, 2016 12:04 pm

easier than you think ...
nut not captive . ( mine was actually not much more than finger tight ).
Flange then comes off easily
I just hooked my old seal out with a screwdriver .
I too settled down to do the job with fear and dread & got myself a new collapsible spacer but never used it .
There's a breather hole somewhere on the top of the diff housing ... i forget where ... but its worth making sure it's not blocked as that will cause pressure to build up inside diff which will blow oil out past seals
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PostPost by: nomad » Sun Aug 07, 2016 4:39 pm

From what I've seen the nut is staked into the key way. Hopefully that wouldn't cause a problem but I would prefer to try removing some of that staking with some sort of home made tool.

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PostPost by: AussieJohn » Sun Aug 07, 2016 7:49 pm

Mine was leaking after replacing the seal, oil was leaking down the thread, used some locktight threadseal which solved it.
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PostPost by: Geoffers71 » Mon Aug 08, 2016 6:58 pm

Right, I've ordered a new seal from Matty. Thought I'd have a look at what was involved today, so backed the car up my ramps and had a close look at what was happening. Seems oil is being flung out and is liberally deposited on the underside of the body as well as dripping on to the exhaust. From other posts I've read on the topic that might have more to do with oil working itself down the splines. I can't say that there appeared to be THAT much oil, if any, dripping from the seal area itself. Anyway I decided to have a go, despite Paul M telling me himself that it would be easier to take the whole diff out. :( Removed the propshaft bolts and lifted it out of the way. Examined the nut with the aid of a mirror and see that looks like an original, i.e. Not locknut !
Not sure what "staking" means, see above, but there are dimples both in the nut and the shaft which coincide. Are these an indication of some form of key? Not a Woodruff as such, but maybe a roll pin of sorts, which prevent the nut from turning on the shaft. If so, how do I get it out? It's below the surface of the nut. I thought they might just be marks to line up nut and shaft, but I've had a half-hearted go at trying to loosen the nut and it's tight, won't move at all. I haven't really given it a proper turn yet as a) it's very difficult to get a 'swing' on the socket and b) I have this nagging doubt about the roll pin.
Can anyone throw any light on whether the nut is pinned ( staked?) or not. If it is how to get the pin out ?
if no pin, then I need to work out how to get turns on the nut. Oh joy, what fun this is. I can see me taking the diff out yet...........or maybe I'll just get a larger drip tray :lol:
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2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: nomad » Tue Aug 09, 2016 3:13 am

When you first mentioned the problem I immediately pictured removing the diff from the car but it may be possible in the car. Good luck! I've yet to tackle such a project in an Elan but have done several in other British car's. I have a tool made up to hold the U joint flange while doing the job and it might help you to make up a similiar tool. Just a bar drilled to bolt to the flange with clearance for the socket used on the pinion nut.

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PostPost by: Gray » Tue Aug 09, 2016 3:13 pm

Geoff

The shaft the nut goes on is punched at the end to retain the nut. I can show you on an old diff if you want to come over, you can also see that my Elan does exist!

Cheers Graham
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PostPost by: Mick6186 » Tue Aug 09, 2016 3:20 pm

I had a similar problem with diff oil leaking down the splines. Rather than disturbing a diff which was working ok I undid the prop shaft flange and moved it to one side. I then thoroughly cleaned the inside of both flanges with degreaser. Next step was a bit messy but used plenty of RTV silicone sealant to fill the interior of both flanges. Finally refitted the propshaft with a good smear of RTV between the flanges and hey presto no leak.
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PostPost by: Geoffers71 » Tue Aug 09, 2016 8:07 pm

Well, I've bottled it :roll: Couldn't get enough room to turn the nut even if it wanted to. I lay under the car staring at the diff for a full 20 minutes, quite soporific actually, I quite enjoyed it :lol: weighed up the steps involved in getting the diff out and decided that now was not the time to be struggling with it......in fact probably no time was going to be right. I'm just too old to be doing this now, a few years ago I'd have tackled it no problem, but lying on my poor back struggling with Rotoflex, Lotocones, a heavy diff etc etc I don't need. Going to have to find someone knowledgeable and pay them to do it.......sometime......eventually.......direckly as the Cornish say.
I did mark where the filler plug lined up with the boot back wall and cut a hole to access it from the boot. Topped up the oil once the car was level again and found it took about 1/3 of a pint :shock:
Mick, if I'd have seen your post a bit earlier I would have tried that. :)
...and Graham, thanks for the invite, might just do that sometime, nice to chat about Lotus anyway :wink: where are you exactly?

EDIT: I did try to find the fabled breather hole, but no luck. Can anyone tell me where roughly I would find it? Is it in the cast iron front case or the back alloy case?
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: elanner » Tue Aug 09, 2016 9:13 pm

The breather hole is simply a small hole drilled in a plug that is screwed into the top of the rear cover. It's just like the filler or drain plugs, but slightly larger, and it has a small hole drilled in it. Nothing glamorous.

Checking it in situ would be a neat trick. :D But it's protected enough that it's hard to see how it might get blocked.

Nick

seniorchristo posted a photo of his recently. You can see the plug by the left arm:

dsc00432.jpg and
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PostPost by: Geoffers71 » Tue Aug 09, 2016 9:20 pm

No wonder I couldn't find it. Thanks Nick, one for the future perhaps :D
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: Wickey » Fri Aug 12, 2016 7:40 am

I remember many many many years ago having the diff nose seal replaced by Yardley Wood and due to the shaft actually having been also worn down with a slight groove (it was a high mileage car) they advised it probably would still leak but not as bad. Proper fix was diff out and possible sleeving or new diff. (big job and expensive) I was working on electical motor designs at the time so had many supplier contacts and managed to source a seal that was the correct outer dimensions but slightly smaller inner diameter across the flip edge. Sorry no details of the part but it sure did the job and fixed the leak............just saying...... as don't always assume a standard new seal will cure the problem and it is hard to believe that a groove could be worn in the metal shaft by the thin edge of a rubber seal but it sure had. :(
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PostPost by: richardcox_lotus » Fri Aug 12, 2016 7:48 pm

Geoffers - so what size socket did you find to undo the filler nut?

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PostPost by: Geoffers71 » Fri Aug 12, 2016 10:10 pm

Richard
11/16 AF. :wink:

Been thinking.....very very dangerous I know.... but it's dripped an egg cupful already, so maybe I will have a go at removing the diff, not now when I can drive the car and keep topping it up, but maybe this winter when I can take my time. After all I did build the bloody thing in the first place.....slowly slowly catchee monkey :lol:
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: Geoffers71 » Sun Sep 25, 2016 2:49 pm

Just know that you're all anxiously waiting to know if anything is happening with my diff :D :D Well...I've only gone and done it :mrgreen: Really took my time, only an hour or so a day, and giving it a rest for a day or two, but diff out, new seal fitted and back in. Sounds easy, but it really is a pig of a job, especially refitting the rotoflexes, despite ensuring they're clamped properly using jubilee clips or my own special clamps that I had made 30 years ago and STILL had in my glory box :D I followed the advice on here and ensured there was plenty of silicone on and around the retaining nut and the splines. Looking good so far, but I guess only time will tell. The old seal, despite being "new" only 25 years ago (car not used during that time), had degraded and deteriorated to the point of no longer being a seal! BTW, I took the opportunity to look for the breather hole that is supposed to be in the casing. No luck to begin with, even in the top of the brass plug located in the top of the case, but eventually I found it, drilled through the side of said brass plug, rather as a hole for a locking wire might be drilled in a hexagon headed bolt head. The hole goes right through the head of the bolt and out the other side. The bolt isn't really a bolt , but a hexagon head on a short tube about 3cm long. Hope that might be a help to anyone looking for the breather :) Anyway, all done and now looking to having a quick blast out, rain permitting. Thanks to all those whose suggestions helped.
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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