AJS & Matchless Owners Club

Well I found the oil leak source ! the round boss part has partially separated from the back piece ( green arrow ). Probably should have had a closer look after blasting and before priming ! Is this a brazing job ?

Also wondering what the metal flange was for ( red circle ) , it is well bashed about but I'm sure it had or has a purpose

Are these back plates easy to come by ?



Edit: After uploading I saw that the photo has a bit of an optical illusion , it is actually looking inside the back plate and if you stare long enough you will see it magically appear dished inwards, however on first look it appears to be the outside


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Your mention of optical illusions reminded me of this TV clip, which whilst probably well known to UK folk, may be new to you
Sorry it doesn't answer your query but it might provide some amusement.

Steve


https://www.google.com/url?sa=t&source= ... 7NOXZ8UUCd

That flang is a catch to grab oil slung up by the primary chain and divert it onto the dynamo chain. Yours is badly damaged, it should look like a U channel which tapers down towards the dunno chain

cfaber wrote:That flang is a catch to grab oil slung up by the primary chain and divert it onto the dynamo chain. Yours is badly damaged, it should look like a U channel which tapers down towards the dunno chain

Does anyone perhaps have a photo showing how this this "catcher" should look like , the part number for my 18S is 013679 (chaincase back-half)

The 'round boss' should have a bit of slide in it to accommodate gearbox movement, so you will never get it fully oil tight.
the shape of the rim of the chaincase should be smooth and uniform, yours shows quite a kink above the dynamo hole. when laid flat should be a good fit with no gaps, that a potential oil leak.

They do come up regularly and not a huge price, so sit back and wait for a good one. If you are good with a forming tool (hammer) its fixable

asterysk_usa wrote: Does anyone perhaps have a photo showing how this this "catcher" should look like , the part number for my 18S is 013679 (chaincase back-half)

This is the closest I could find.

Rob C

alanengineer wrote: the shape of the rim of the chaincase should be smooth and uniform, yours shows quite a kink above the dynamo hole. when laid flat should be a good fit with no gaps, that a potential oil leak.
They do come up regularly and not a huge price, so sit back and wait for a good one. If you are good with a forming tool (hammer) its fixable

It's new unused stock and on eBay now for £85. https://www.ebay.co.uk/itm/Matchless-AJ ... Sw7qRdvb2c

(Being sold by 'ITMA' whom some may remember from these Forums )
Fit the chaincase with the 'new' design club seal: http://www.amoc-parts.com/store/comersu ... duct=23441

The 'round boss' should have a bit of slide in it to accommodate gearbox movement, so you will never get it fully oil tight.

This gives an idea of the clutch shaft oil baffle arrangement although I'm not sure whether it was a factory fitment on all 50's chaincases, my '54 has never had one....

To clarify, the case with the circular deflector around the mainshaft was in use up to 1955 and it was fixed in position. The later sliding seal type in Spriddlers illustration was from 1956-57. It's a far better design and can be retro fitted to earlier models. There is however a very successful mod that can be carried out to the earlier case that help prevent the ingress of water and the escape off oil and can be carried out on road models. A dished competition deflector plate can be fitted between the gearbox sprocket nut and sprocket, and on the rear of the case either a felt or leather washer can be fixed with contact adhesive.

Slightly off subject, but where does one get one of these dished competition deflector plates? I have a '54 18S and would like to improve the primary chaincase sealing. I have suffered from water ingress, turning the oil to mayonnaise, and although the chaincase seal does not leak, I still lose oil from Dynamo or gearbox orrifices. Cheers, Andy

ajscomboman wrote:To clarify, the case with the circular deflector around the mainshaft was in use up to 1955 and it was fixed in position. The later sliding seal type in Spriddlers illustration was from 1956-57. It's a far better design and can be retro fitted to earlier models. There is however a very successful mod that can be carried out to the earlier case that help prevent the ingress of water and the escape off oil and can be carried out on road models. A dished competition deflector plate can be fitted between the gearbox sprocket nut and sprocket, and on the rear of the case either a felt or leather washer can be fixed with contact adhesive.

Thank you for the clarification, I have been scratching my head trying to work out how the circular deflector was meant to move !

I will keep an eye out for the later sliding version, I am on a mission to have an oil free floor (and I would also like to stop global warming )