Another oil leak mystery

[Pete Gray]

Going over old ground but i've just stripped down my A7 primary mainly to check why the adjustment on the tension was at maximum - I found a couple of broken chain rollers !
But at the same time I was soert of hoping to find a clutch centre with the incorrect spiral as the reason for the damned thing slinging ATF over the silencer whenever there's any level in the chaincase. Not the case, the centre throws the right way.
I've taken these photos and ask for any comment which might help, one noticeable issue is due to wet sumping there is engine oil issuing from the bottom 5/16" screw hole. The primary seemd to have more oil that I had expected and I wonder if I'm getting seepage through the crank shaft seal causing the "leak" from the clutch centre. The oil was certainly discoloured from ATF red!
If so is it possible to fit a new seal from the primary side ?

If only I could justify the money for a belt drive.

[muskrat]

 G'day Pete,
                 looks like the clutch centre could do with a polish at the scroll, the end looks rough.
 The seal can be replaced insitu, but I doubt if that's the prob. If all gaskets and threads are good the only place left is the sliding plate seal or the felt (I see you use cork) behind.
Cheers

[chaterlea25]

Hi Pete,
I think Musky needs to go and have his specs rechecked ?? as I can see a felt seal in your photos???
I prefer to use cork and use a non setting sealer on the sliding plate side
Anyway!!!
Looking at your setup it looks that the sliding plate is a pattern item?? any of these I have looked at have the "hole" pressed through, which is both oval and oversize 
I have also found that the felt "seals" supplied seem to act as sponges which soak up the oil and then leak it
onto the ground

Solutions???

I have both cut out the middle of the sliding plate and on different occasions (different bikes) turned up a new close fitting centre and re rivited it to the plate or on another I brazed a new bush to the plate and bored it to size
On the latest projects I'm going to make a bush with an oilseal fitted on the inside (clutch side) and a close fit on the shaft at the back, I will either braze this to the plate or rivit in place of the old piece.
Then cut off the scrolled portion of the clutch adaptor

Sealing the clutch with a lip seal requires a breather vent for the primary case, drill a tiny hole in the filler cap or invent your own???

HTH
John O R

[muskrat]

 Yep I do need new specs. The felt is corkish colour from the ATF.
I think either or both Brien and Orabanda use seals (lipped) in their sliding plates as well.
Gee I luv my dry belt primary. The '51 is next to get one.
Cheers.

[Hubie]

Musky,

Where do you get your belt drives from?  Am going to do the same for my a10.  I also cut the scroll off the back of  my clutch centre and then fitted an oil seal in the sliding plate which goes directly onto the mainshaft. Works great but I still get a dribble now and then from between the inner and outer cases.

Cheers,
Hubie.

[muskrat]

 G'day Hubie,
                  A bloke down your way http://www.lytedrive.com.au/index.html
 He can be a bit slow and funny to talk to. Mine is a sNorton Commical type but I see he now does 6 springers. cost $1K. A mate also has one on his Matchy 750 for a few years with no probs.
Cheers

[wilko]

Yes, Scabber loves to talk the talk! Might be an hour before you get to the point!

[Pete Gray]

On looking again I've realised that the scrolled boss is only just entering the sliding plate by a couple of milimeteres (that sounds like a kinky sex thing!)
I've also decided to have a new centre boss machined for plate, a closer fit and to increase the depth that the scroll fits into also incorporating a lip seal to the gearbox shaft. There is room to do both and hopefully this will be a double oil barrier.
A question for John :-
Where do you source the cork rings from - I can only see felt ones available ?

[chaterlea25]

Hi Pete,
I get some cork sheet from an industerial supplies co.
and cut them from this, I glue it onto the inner case and sand to thickness
in your case maybe the thicker cork will cure the scroll / plate problem
Beware of bending the plate too much and check for clearance behind the clutch chainwheel
HTH
John O R

[Pete Gray]

I've had the back plate modified, see the photos. Of course nothing is simple and I had quite a struggle with the diameter of the scroll being too good a fit in the new boss centre and binding when the centre bolt was tightened, the back plate doesn't sit perfectly square either giving some interference. So spent the afternoon grinding and fettling and, I hope, have now got a satisfactory fit.
The O ring should take care of any chucked ATF so fingers crossed.
I've got a Paul Goss oil filter kit on it's way so it'll be a while before we're ready to roll.

[renos-a10]

hi
it's possible to have the mm of oil seal?

[muskrat]

It won't be the same in your plunger, Renos. That's for a swingarm type. Or are you secretly building one?
Cheers

[renos-a10]

Hi Muskrat ,

 Thanks for your quick reply!! Yes i know that but i will fix my friend A10 swing arm with this problem.So i think that if it's possible to know the mm ( or part no. of oil seal ) is better for me.

Thanks
Renos

[renos-a10]

Also i would like to ask if it's possible to have the part number for oil seal and for the plunger because i think if i have time i will to the same and on my plunger.

Thanks in advance for your help!!
Renos

[muskrat]

Plunger oil seal part # 67-1242
http://www.a7a10.net/forum/index.php?topic=712.0  is one that Richard did.
Hopefully Pete will see this and give details of his s/a mod.
Cheers