Gearbox output shaft bearing

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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clanger9
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Gearbox output shaft bearing

Post by clanger9 »

I think my gearbox output shaft bearing is on the way out. Not only does my gearbox leak oil out of the left hand side, but it's started to grumble a bit and there's a lot of side-play on the input shaft.

Assuming it is knackered, is this the list of parts I need to fix a late-model CSR 'box?

044075 Gear driving main with bushes
041266 Mainshaft bearing
041267 Main Gear Bearing Oil Seal

Anything else I should replace while I'm in there?

The job looks straightforward enough, but I think my main challenge is going to be sourcing the parts. The output gear looks to be totally unavailable, for example. The seal seems to be out of stock in the spares scheme. The bearing is available, but blimey it's expensive! :shock:

Time to post a "Wanted ad", I think...

[edit] Just noticed that the seal is available from Norvil. As is the gear: £125!! :o
1989 Moto Morini Dart 350
1993 Ducati 750SS
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dave16mct
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Re: Gearbox output shaft bearing

Post by dave16mct »

Can't you just replace the bushes in the gear? The main bearing is about £27 and the seal is about £6.
Dave.
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Ozmadman
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Re: Gearbox output shaft bearing

Post by Ozmadman »

dave16mct wrote:Can't you just replace the bushes in the gear? The main bearing is about £27 and the seal is about £6.
Dave.
The main bearing (041266) is in fact about £70 it is a special size with no inner race as it runs directly on the bearing track on the output/sleeve gear. If you belong to the Norton owners club
http://www.nortonownersclub.org/html/sp ... spares.pdf they list that part number @£30 so if this is the current price then I would bite their hand off and buy it. I got mine a few years back now from simply bearings (RNU205) as at the time the club was out of stock but the price was similar, see pics or original and replacement bearing
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Last edited by Ozmadman on Sat Apr 08, 2017 12:46 am, edited 1 time in total.
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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Ozmadman
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Re: Gearbox output shaft bearing

Post by Ozmadman »

dave16mct wrote:Can't you just replace the bushes in the gear? The main bearing is about £27 and the seal is about £6.
Dave.
Yes you can replace the bushes in the gear 2x 041275 I think... but that isn't the whole picture. As mentioned the output bearing runs on a bearing track which is machined as part of the output/sleeve gear this track becomes pitted and renders the whole gear as useless unless you know someone who can sleeve it, machine it back to size and then case harden it!!
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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clanger9
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Re: Gearbox output shaft bearing

Post by clanger9 »

Yep, Ozmadman has got it spot on - I could replace the (cheaper) inner bushings, but from the side play and rumble, I suspect the outer bearing is U/S as well. It's probably corroded, because the gearbox was stored for a long time without oil. So I'm fairly certain I need a new gear.

I haven't dismantled the 'box, as I thought I'd try it first - it works perfectly, apart from this issue. Given the price of the bits, I'll probably just suffer it until the end of the year. :?

Presumably there are other seals and bearings (layshaft?) that should be changed while I'm fixing it? It weeps a bit from the gear selector shaft, so example.
1989 Moto Morini Dart 350
1993 Ducati 750SS
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dave16mct
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Re: Gearbox output shaft bearing

Post by dave16mct »

OK I've just twigged you're talking lightweight gearbox. I was wondering where you were betting that bearing from! I'll get me coat (again)
Dave.
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ajscomboman
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Re: Gearbox output shaft bearing

Post by ajscomboman »

dave16mct wrote:OK I've just twigged you're talking lightweight gearbox. I was wondering where you were betting that bearing from! I'll get me coat (again)
Dave.
And don't forget your cap, close the door on the way out. :rofl: :rofl:
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Ozmadman
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Re: Gearbox output shaft bearing

Post by Ozmadman »

clanger9 wrote: Presumably there are other seals and bearings (layshaft?) that should be changed while I'm fixing it? It weeps a bit from the gear selector shaft, so example.
there is a lay shaft bush which is quite likely to be worn and a small bearing at the other end of the main shaft which ideally should be replaced as a matter of course whilst the box is apart as they are a bit prone to breaking up if worn. When rebuilding the box do that end main shaft nut up tight and loctite it so it doesn't come undone and wreck the bearing. There is a kickstart shaft bush and a selector gate shaft bush but neither of these usually require attention. As for seals, apart from the main shaft seals there are only orings, one for the kickstart shaft, one for the gear selector shaft ( they do a modified version for these two with a X suffix to the part number, which actually are both the same seal for both shafts, so get these if possible and two small ones for the selector rod that passes through thee selector shaft. Finally, two case gaskets.
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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clanger9
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Re: Gearbox output shaft bearing

Post by clanger9 »

Brilliant, thanks Ozmadman! That's what I needed to know. :beer:
1989 Moto Morini Dart 350
1993 Ducati 750SS
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Ozmadman
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Re: Gearbox output shaft bearing

Post by Ozmadman »

clanger9 wrote:Brilliant, thanks Ozmadman! That's what I needed to know. :beer:
Just to clarity, when I said main shaft seals that should be seal as the only seal is the big one you already know about behind that output drive cog. I have taken a few of these apart and generally mine have been in good condition apart from what I have already mentioned. If you do need to replace the lay shaft bronze bush PLEASE CHECK IT CAREFULLY BEFORE FITTING the flange thickness MUST be the same, taking account any slight wear on your old one, as your old one. Club spares ones were incorrect in that department with a flange far too thin which would allow the end gear on the lay shaft to rub on the gearbox casing. There is a thread of mine on here that shows pictures of both.
Last edited by Ozmadman on Mon Apr 10, 2017 12:16 am, edited 1 time in total.
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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