Gearbox help

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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Gearbox help

Postby Ludwig » Sat Nov 09, 2013 5:10 pm

Hello,
I'm involved in the overhaul of a G8 of a friend of mine.
At the inspecton of the gear box, we found a badly worn small sleeve on the outpt shaft, which acts as
bearing track for the mainshaft bearing.
Wall thickness is less than 1mm.
A look into the manuals doesn's show this sleeve, it seems that the shaft itsself acts as bearing track.
The diameter of the shaft is actual 1 1/8", maybe someone has skimmed it down to carry the sleeve as
repair.
The remainig bearing (without inner race) seems to have an outer diameter of 2" and a width of 1/2".
To make the confusion complete, the club's spare scheme lists the bearing (#041266) as a NU 205,
which is normally listed as a metric bearing with 50mm od, 15mm width and 15mm id.
Can anyody enlighten me?
Thanks in advance,
Ludwig

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Re: Gearbox help

Postby Ozmadman » Sun Nov 10, 2013 2:43 am

Ludwig wrote:Hello,
I'm involved in the overhaul of a G8 of a friend of mine.
At the inspecton of the gear box, we found a badly worn small sleeve on the outpt shaft, which acts as
bearing track for the mainshaft bearing.
Wall thickness is less than 1mm.
A look into the manuals doesn's show this sleeve, it seems that the shaft itsself acts as bearing track.
The diameter of the shaft is actual 1 1/8", maybe someone has skimmed it down to carry the sleeve as
repair.
The remainig bearing (without inner race) seems to have an outer diameter of 2" and a width of 1/2".
To make the confusion complete, the club's spare scheme lists the bearing (#041266) as a NU 205,
which is normally listed as a metric bearing with 50mm od, 15mm width and 15mm id.
Can anyody enlighten me?
Thanks in advance,
Ludwig


Presume you mean G5? Ok, I am getting to be a bit of an expert on this part of the gearbox having had mine apart many times and in the last couple of days have spent ages scouring the bearing manufactures sites for the correct bearing. This bearing is a real odd ball, is not a standard size and very expensive to buy. It does not have a inner track to run on as the rollers run directly on the output shaft which, as you say, is the bearing track(it is not a separate sleeve). There is a separate track but this presses over the spline of the output shaft for the main seal to run on. The size is 52mm o/d 15mm width and 32mm i/d. Be very careful if someone tells you that an NU205 or a 2NU05 is the correct one (and which is stamped on the bearing if you have the original SKEFCO one) and which are sold with an inner track which you are to supposedly remove. This won't fit, I have tried it with the exact same bearing because with the track removed the shaft won't fit in the rollers as the inner diameter of the rollers on this bearing is 31.5 mm and the shaft is 32mm. The correct bearing (AND IF YOU WANT TO HOLD FIRE FOR A COUPLE OF DAYS FOR ME TO CONFIRM THIS IN PRACTISE AS I AM WAITING FOR MINE TO ARRIVE) can be had from Simply Bearings but you won't find it on their website you will need to email them. Go to this page, it is the SKF search page
http://www.skf.com/skf/productcatalogue ... nation.jsp put in the dimensions above in both columns and highlight "cylindrical roller bearings".. the part number you get come up is RNU205, this, and I will definitely confirm in a few days that this is the correct one and is sold without the inner track. this also has a steel cage as opposed to the nylon/plastic ones in the other so called correct bearings. AND NOW THE COST... £52.20 + £10.44 vat = £62.64 with free shipping and this is the cheapest I can find for the correct one, as I say, I will confirm definitely when it arrives. Ask me any other gearbox questions as I have had a few of these apart and re-built them but don't ask me why you have so much lay shaft end float, if you have, cos I don't know that and nor does anyone else it seems. Finally, if you need the lay shaft bush that goes in the end casing don't get it from the club spares(sorry) as their's have a seriously undersize flange and your top gear will rub on the casing and wreck it, try Russel motors or AMC classic spares, check out the picture and you will see what I mean, the thick one is the correct one and just in case anyone is wondering this isn't the reason for my excessive end float as I have the correct thick one fitted. Looks like you may also need another output shaft as it appears that someone has modified it in the past to suit the wrong bearing or to compensate for wear.

Paul
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Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: Gearbox help

Postby Ludwig » Sun Nov 10, 2013 12:45 pm

Hello Paul,
it's an AJS Model 8.
I noticed my mistake after posting and nearly couldn't sleep last night!
Thank you very much for your comprehensive answer.
The gearbox is in the moment at further friend of the owner, who has skill to do the repair, but he's not a club member.
I'll forward your infos to him.
Lightweight are extremely rare her in Germany.
Best regards
Ludwig

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Re: Gearbox help

Postby Ozmadman » Sun Nov 10, 2013 11:56 pm

Ludwig wrote:Hello Paul,
it's an AJS Model 8.
I noticed my mistake after posting and nearly couldn't sleep last night! Thank you very much for your comprehensive answer.
The gearbox is in the moment at further friend of the owner, who has skill to do the repair, but he's not a club member. I'll forward your infos to him.
Lightweight are extremely rare her in Germany.Best regards Ludwig
No worries, guessed it was a typing error(you can edit it after posting if you need to) mine is a Model 8 as well (1960), Not sure how you would go about repairing the bearing track on that output shaft though but it must be able to be done I should imagine and maybe it could be made to fit a standard and cheaper bearing??

Paul
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: Gearbox help

Postby Ludwig » Mon Nov 11, 2013 1:43 pm

Hello Paul,
Herbert, the guy responsible for the gearbox, told me that your info did exactly confirm his findings.
And your article will help to find a solution. Unfortunately, Herbert had an accident with a Commando 1 1/2 years
ago. The effect on the medical treatment after the accident was one leg shortened for about 10cm.
In two weeks he goes to the hospital again, they are going to try to extend it close to it's original length.
That's a long process, so the gearbox has to wait.
I'll keep you in the loop what's going on.
Thanks again,
Ludwig

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Re: Gearbox help

Postby Ozmadman » Mon Nov 11, 2013 9:12 pm

Ludwig wrote:Hello Paul,
Herbert, the guy responsible for the gearbox, told me that your info did exactly confirm his findings.And your article will help to find a solution. Unfortunately, Herbert had an accident with a Commando 1 1/2 yearsago. The effect on the medical treatment after the accident was one leg shortened for about 10cm.
In two weeks he goes to the hospital again, they are going to try to extend it close to it's original length.That's a long process, so the gearbox has to wait.
I'll keep you in the loop what's going on.Thanks again,Ludwig
That's some stretching!! nearly 4 inches for us imperialists, all the best to Herbert

Paul
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: Gearbox help

Postby Ozmadman » Wed Nov 13, 2013 1:58 pm

Just to confirm, the bearing has arrived and it is spot on and fits perfectly. Here are two pictures old and new
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1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: Gearbox help

Postby Julian_S » Wed Nov 13, 2013 3:10 pm

From Simply Bearings? They are a good outfit, a few years ago I wanted a clutch release bearing for an old Thwaites dumper, it's a pretty much bespoke item but I found a number on it and SB via some sort of national computer database found just two remaining in the whole of the UK. They got me it the next day and I was very pleased indeed :-)

FWIW, I'd recommend them any day over a rival company, The Bearing Boys.

Julian

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Re: Gearbox help

Postby Ozmadman » Wed Nov 13, 2013 3:20 pm

Julian_S wrote:From Simply Bearings? They are a good outfit, a few years ago I wanted a clutch release bearing for an old Thwaites dumper, it's a pretty much bespoke item but I found a number on it and SB via some sort of national computer database found just two remaining in the whole of the UK. They got me it the next day and I was very pleased indeed :-)FWIW, I'd recommend them any day over a rival company, The Bearing Boys.Julian
Yes from SB and it wasn't even listed on their website! I had a search on SKF's site once I got the measurements (cylindrical roller bearings without an inner track) and found what I was 99% sure was the correct one. I emailed SB and they said they do have it in stock!! excellent service and loads of help and answers to my questions very quickly.. Well recommended.. Not cheap though, but then nor is another gearbox rebuild, should I risk a rubbish bearing..

Paul
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

Posts: 345
Joined: Fri May 31, 2013 6:57 pm
Location: Warrington, Cheshire

Re: Gearbox help

Postby Julian_S » Wed Nov 13, 2013 5:19 pm

Ozmadman wrote:
Julian_S wrote:.. Not cheap though, but then nor is another gearbox rebuild, should I risk a rubbish bearing..

Paul


Sadly all Imperial bearings now cost the earth, especially the larger sizes. I rebuilt a series Landrover gearbox a bit ago and I had a long hard think and reused the ball races in the transfer casing as they were about 50 squids each. Metric would have been a tenner :-(

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