Gearbox output shaft bearing

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Ozmadman
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Re: Gearbox output shaft bearing

Post by Ozmadman »

Yes clearly I am not very observant, no main shaft sticking through the sleeve gear!!! yes it will wobble about until the shaft is in and with your nice new bushes in the gear it should be fine!! let us know the result when all together
Paul
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Steve S
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Re: Gearbox output shaft bearing

Post by Steve S »

Yes the shaft, sleeve gear and sprocket are now perfect thanks.

Re-assembly was going well until I experimented with fitting the outer cover. I've figured out the way the footchange mechanism works and the position for the quadrant but can't press home the cover as I think the kickstart spring is binding on the inside of the moulding inside the cover. I've tried adjusting the spring's tension but every position seems to foul it.

Any ideas please as the workshop manuals or the rebuild article don't mention this.

Steve S.
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clanger9
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Re: Gearbox output shaft bearing

Post by clanger9 »

Are you sure it's not just binding on the gear change fork? It's really difficult to get the selector mechanism to line up (though waggling the selector shaft seems to help).

Anybody know the correct method for getting the cover on? I just know it's a right faff each time I tried it...
1989 Moto Morini Dart 350
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Steve S
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Re: Gearbox output shaft bearing

Post by Steve S »

Thanks Clanger, I excluded that possibility by offering it up without the fork in place and the kick start spring is definitely binding on the housing inside the cover. I have now tried winding up the spring with the kickstart lever and apart from it being a trick that needs 5 hands to attempt it doesn't seem to help!

Steve S.
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Re: Gearbox output shaft bearing

Post by Steve S »

Hi here are two photos showing marks the kickstart spring has made inside the housing and also how non-straight it sits, any suggestions please as I'm pretty sure this is what's stopping the cover slipping on, Steve S.
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Janet
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Re: Gearbox output shaft bearing

Post by Janet »

soory, I'm having a little difficulty seeing it properly but it looks to me that you have a washer underneath the spring which, as far as I recall, it shouldn't have. It should have a thrust washer neck to the kickstart ratchet spring. Is is possible you've fitted the washer next to the wrong kickstart spring?

Even when properly fitted, a spring won't necessarily sit perfectly straight around the shaft because of the forces exerted as it tries to unwind, but there should be enough clearance for you to fit the end cover.

Edit: I am, of course, now doubting myself.
Edit 2: It seems I was right to doubt myself as I was wrong. See later posts.
Last edited by Janet on Wed May 24, 2017 7:35 pm, edited 1 time in total.
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Steve S
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Re: Gearbox output shaft bearing

Post by Steve S »

Yes there is a washer behind the spring Janet and looking at the exploded engine pdf it should be inside behind the ratchet spring as you say. I haven't taken it off yet but I can see it is forcing the shaft of the hook end of the spring upwards which is making the spring sit non square. I have also noticed that I'm missing two washers to the gear selector shaft; these were parts which I had not dismantled and it looks like they were re-assembled incorrectly by the person who made such a mess the last time the box was touched!

Thanks, Steve S.
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clanger9
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Re: Gearbox output shaft bearing

Post by clanger9 »

I can't be certain, but I think the washer is meant to be there. It's not shown in the exploded diagram, but you can see it clearly on my "good" gearbox:
IMG_1155.jpg
The washer under the spring is also just about visible in the workshop manual (figs. 49 & 50):
IMG_1158.jpg
Just to be different, my "scrap" gearbox doesn't have a washer fitted:
IMG_1157.jpg
However, the outer cover still fits over the kickstart spring just fine. Though the spring also looks a bit different (it has fewer turns, for example).
I hope I'm not just adding to the confusion here... ;)
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Last edited by clanger9 on Wed May 24, 2017 7:24 pm, edited 1 time in total.
1989 Moto Morini Dart 350
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clanger9
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Re: Gearbox output shaft bearing

Post by clanger9 »

Aha, I think I found the answer: "...[later gearboxes] are fitted with a circlip 042900 encircling the kickstarter axle 042130 with a thrust washer 042091 to prevent pre-loading also wear on the axle bush" - p.51 of the workshop manual.
1989 Moto Morini Dart 350
1993 Ducati 750SS
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clanger9
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Re: Gearbox output shaft bearing

Post by clanger9 »

Yep, that's it. The washer and circlip were added later to stop the return spring from pulling the kickstart pinion against the bush.

There's a flat thrust washer between the pinion and the bush. You can clearly see the circlip on the shaft as well:
IMG_1159.jpg
The "domed" washer fits over the shaft and gives the circlip something to butt up against.
IMG_1160.jpg
Finally, the spring fits over the top to hold the whole thing together. This is actually a bit of a rubbish modification, because it just means the circlip is pulled up hard against the domed washer by the spring, meaning the washer wears away instead...

Back to your problem with the spring fouling: is there a chance you've just put a bit too much pre-tension on it?
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1989 Moto Morini Dart 350
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