AJS 1954 18S Rear Swing Arm

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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AJS 1954 18S Rear Swing Arm

Postby deejaybrown98 » Sun Apr 14, 2019 11:24 am

Hi, Just joined Jampot and this is first post.
I acquired above 'loosely built' bike CEU 946 and just getting round to taking it apart to see what i have and what is needed.
The bike has been painted at some time and the Rear swing arm seems to have been painted over in situ.
I have removed the Jampots and the arm doesn't move except with encouragement from a heavy rubber mallet.
How freely should the arm rotate?
I'm not sure if problem is the paint or if there is some internal adjustment required.
At the moment I haven't even been able to remove the oil level screw due to the paint over it.
How are the pivot end caps removed? Are they just prised out of if remove the layers of paint?
Would appreciate any offered advise.
Many thanks
David Brown

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Re: AJS 1954 18S Rear Swing Arm

Postby Rob Harknett » Sun Apr 14, 2019 12:10 pm

The caps are held by a spoke. Undo the centre screw with draw the spoke. Caps will then fall off if not stuck with paint. The SA moves up/down on a bush, you could just try and un seize it. Lay the bike over each side and flood it with penotrol after removing the end caps. Surely you could have seen these parts in your parts list, how to remove etc. in your instruction book and workshop manual. If you do not have these books, you should not touch the bike until you get them.

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Re: AJS 1954 18S Rear Swing Arm

Postby Mick D » Sun Apr 14, 2019 12:15 pm

Hi

The swinging arm should rotate freely, drop under it's own weight or with minimal finger pressure. Yours sounds like the pivot has rusted and is no longer rotating freely within the bronze bushes.

The end caps are retained by a spoke through their centres - if your arm is assembled correctly the nipple should be on the timing side. Note to remove the spoke and swinging arm you will need to remove the primary chain cases.

SA Cap.png


The cap screw in the photo is temporary - you should have a slotted screw there.

Regards Mick
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Re: AJS 1954 18S Rear Swing Arm

Postby Groily » Sun Apr 14, 2019 12:20 pm

It should pivot fairly easily with the rear units off. Steel pin, bronze bushes and detachable discs at the ends with long through-screw like a spoke & nipple, and off-centre other one for level. Also thick felt washers to retain some slime . . .
Probably suffering from lack of lubrication as it's often ignored - I don't think paint alone could have the effect described.
I ignored one of mine (also '54, but a twin) for far too long and it seized up a few months back. The arm wouldn't move AT ALL even with a heavy mallet, big tube over end of fork, etc.

So . . . I had to get the alloy casting off, press out the pin (which took no fewer than 8.5 tonnes to budge and made a noise like a howitzer when it did), and start again. A fairly filthy job (literally as well as in terms of the PITA factor) as there are a lot of mucky bits to strip off to get to things if there's no alternative. As in: toolbox on drive side, battery & carrier, primary drive complete, seat, mudguard, regulator, chainguard, rear wheel etc. Think I even had to undo the oil tank too, to get the casting's fasteners out.

You might be lucky and be able to get it to move freely with some brute force and perseverance, and then get some fresh lube where it's needed - but then again, the bushes and / or pin might unfortunately be past it. The casting is a bit exposed, and shite does get in there - my bushes/pin were well seized on the inner ends, even though the outer sides seemed to have at least some lubricant in evidence.

Not a fun job, sadly.
(Just saw Rob's comment - and yup, here's hoping Fate gives you a break!)

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Re: AJS 1954 18S Rear Swing Arm

Postby Pharisee » Sun Apr 14, 2019 3:46 pm

The swinging arm assembly that came with my '53 G3 basket case was in a very rough condition and I certainly couldn't move it by hand. Unlike Groily, though, I didn't need 8.1/2 tons of pressure to get it apart. It succumbed to a length of M12 studding, a piece of thick wall steel tube and a suitably sized socket. It made some screeching noise as I pulled the pivot pin through the bushes but it did come apart. The pivot pin was scrap but the bushes were OK. After cleaning the crud off them, the new pivot pin fitted perfectly. The swinging arm and alloy csting were powder coated and assembled with new felt washers, end caps and securing nipple.

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Re: AJS 1954 18S Rear Swing Arm

Postby Andy51 » Mon Apr 15, 2019 8:03 am

Hi David, I wrote an article for Jampot a few years ago on removing and replacing swinging arm bearings. PM me and I will send you a copy. Andy

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Re: AJS 1954 18S Rear Swing Arm

Postby deejaybrown98 » Mon Apr 15, 2019 10:47 am

Hi, Many thanks for all the responses and the info.
Most the the items around the swing arm are already removed as they were only loosely attached.
I have tried to remove the centre screw but with all the paint over it it I didn't want to go to hard on it and chew it up.
I will wait until next week when visitors have left and carefully try to clean the head of the screw.
Will let you know how I get on.
David Brown

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