Author Topic: Clutch oil seal and sleeve gear bush  (Read 2918 times)

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Phil C

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Re: Clutch oil seal and sleeve gear bush
« Reply #60 on: 24 July, 2020, 08:33:06 »
Looks like a closed-end bush?
Unless the hole is stepped (counterbored) and it's a cap?
 Phil
« Last Edit: 24 July, 2020, 09:06:21 by Phil C »

Phil C

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Re: Clutch oil seal and sleeve gear bush
« Reply #61 on: 11 August, 2020, 14:04:13 »
Hello everyone, To remind you, it's a 1965 B40F. Having fitted my NOS clutch cable, I went for a quick run out this morning, just a couple of miles. The clutch seemed okay. When I got back, I put the bike on its sidestand and had a peep underneath to see what was happening regarding any oil leaking.  The photo shows what I saw.

I think (my colour vision is very poor, but I got my wife to have a look also) the oil you can see has an orange hue about it, which tells me it's come from the gearbox (where I put the dye.) The vertical surface beneath the layshaft bush is not visible, but I ran my finger along that surface about 15 mins after parking up, and it felt dry, but I guess any oil, being warm, might simply have run off it by then (should have checked sooner.) But as the bike is on its sidestand wouldn't oil still be coming from there if that was the source of the leak?

You'll see a large drip of oil hanging in the foreground of the pic, so quite a way from the bush, and also on the horizontal surface, along the line of what I think is a casting seam. It is also on the horizontal surface out of sight in the foreground.  The vertical surface (facing us) where I had the dribbles before felt a bit oily, that's all. As you can see, the drain plug looks fairly dry.

I know we've discussed this before, but can I just recap, and check where the gearbox oil could be coming from (yes, I know, the gearbox.) Am I right in saying it must be from one or more of the following?: 
- the seal behind the clutch;
- the layshaft bush;
- the drain plug.
Any other possibilities?

Thanks as always,   Phil.

idie

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Re: Clutch oil seal and sleeve gear bush
« Reply #62 on: 11 August, 2020, 14:16:50 »
Maybe a porous casting. I know it happens on engines maybe it can happen on gearboxes. Or could it be a crack that opens up when hot.

Dean Southall

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Re: Clutch oil seal and sleeve gear bush
« Reply #63 on: 11 August, 2020, 15:06:22 »
If you have  a wprn shaft that won't let the seal remain oil tight you can get a repair sleeve. I have used these and found them reasy to install and effective

https://simplybearings.co.uk/shop/Products-Speedi-Sleeves/c4747_5335/index.html
BSA: turning ordinary men into mechanics since 1910

Phil C

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Re: Clutch oil seal and sleeve gear bush
« Reply #64 on: 11 August, 2020, 15:30:21 »
Okay thanks very much Dean, that's worth keeping in mind.

I've just been for another spin down the road, and this time felt the vertical surface under the layshaft bush as soon as I parked up. There was oil on it. But there was on the other surfaces around there too.

Anyway, re my post earlier today, any thoughts anyone on possible sources of the leak(s)?

Phil

Phil C

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Re: Clutch oil seal and sleeve gear bush
« Reply #65 on: 24 June, 2021, 16:31:31 »
Well, time has passed, and my search for the source of s slight leak has been unsuccessful again. I've had the clutch out, replaced the seals, renewed the circular plate gasket, also the alternator wire grommet (and incidentally done loads of other stuff which I came across) but the dribble remains (see photo.) I'm annoyed with myself for not checking to see if the bush on the main shaft is split or not (I was so distracted with other things I found that needed doing.) Can't see a split on the photo but guess it could be out of sight. Anyway, re the dribbles, ideas welcome as always. I'm pretty sure it's chaincase oil not gearbox oil (I have a very slight gearbox oil leak also and that's a different colour.). Phil

Phil C

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Re: Clutch oil seal and sleeve gear bush
« Reply #66 on: 25 June, 2021, 10:48:54 »
Re the above, I can see I'm going to have to take the clutch out again to check if the bush is split longitudinally or not. Sigh. Maybe come the autumn/winter. I wonder, could oil leak out of the chaincase by tracking along the threads of the countersunk screws which hold the circular cover plate? They are done up nice and tight, but do you think oil could nevertheless escape that way? Clutching at straws here maybe.  Phil