Gearbox Identification

Information relating to Matchless and AJS Models built prior to 1939
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upperstoker
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Joined: Sat Nov 17, 2012 8:54 pm
Location: WILTSHIRE UK

Gearbox Identification

Post by upperstoker »

I have a 1938 model 26 with a Burman gearbox which is in need of some repairs. The shell is stamped with 7HPBD 17697. Does this relate to any particular type of gearbox that I can refer to then looking for spare parts?
My basic findings are leading me to the box being a CP or BA, would one of these be right?
I have included a few images of the box in question, (sorry they are upside down! not sure how to correct them)
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dave16mct
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Re: Gearbox Identification

Post by dave16mct »

No its not a CP or BA, which are much heavier duty. Its a Burman HP1 which is a lightweight gearbox with smaller output sprocket for a lighter chain. I'm sure Rob will give you more info. He's the Pre-war officer.
Cheers Dave.
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Duncan
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Re: Gearbox Identification

Post by Duncan »

Alan

You might find this link useful: http://archives.jampot.dk/technical/Tra ... alogue.pdf
upperstoker
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Location: WILTSHIRE UK

Re: Gearbox Identification

Post by upperstoker »

Thanks guys
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Rob Harknett
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Re: Gearbox Identification

Post by Rob Harknett »

Yes Burman Model H. Of which there were, I believe 3 different versions. Hand change, Foot change with external selectors + the internal selector model shown. Actually the 1938 AJS model 26. had a new little oval shape stream lined gearbox. That did not have speedo drive , as speedo drive went to the front wheel. In 1939 the oval shape gearbox was only used on 250's. You may have an early 1938/26 using up old stock. However old stock was usually used up on the cheaper coil ignition models and side valve models. Spares for these boxes are very hard to come by, to non existent. I had a batch of 20 speedo gears and cables made. They soon went. If your speedo cable breaks, leave it in the box, That holds the speedo drive in. The speedo drive gear can easily come out and get lost. Kick starters are usually found with 1 to 3 of the first teeth missing. You loose a bit of kick because of that. You have to make do with that, so don't jump on it too hard and brake off more teeth. Gear changing is not easy. An egg cup full of oil in with the grease helps once it gets warmed up. Again some you have to put up with if the want to ride the bike. All part of the fun. You may have to change down through 2 gears then back up one to find a gear you want. Changing up is usually OK. One down and 3 up may catch you out if you also ride a post war AJS.
upperstoker
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Joined: Sat Nov 17, 2012 8:54 pm
Location: WILTSHIRE UK

Re: Gearbox Identification

Post by upperstoker »

Thanks Rob for the background and tips.

Currently it is slipping out of second gear when accelerating. I am obtaining a new pawl spring to see if that helps. I have not stipped the box as yet to see what else might be at fault. New to this game and it would be the first time I have stripped a gearbox - there has always got to be a first time!

How much grease (plus an egg cup of oil) should I be putting into the box?
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Rob Harknett
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Re: Gearbox Identification

Post by Rob Harknett »

Mines been slipping out of gear for ages. Many prefer a semi fluid grease. Cannot recall amount. It must be stated in the manual. Put a bit of oil in at the start of the riding season, then on if you don't ride often. Soon chucks it out. It will take a fair run for the gearbox grease to warm up and gear change improve. Changing down is most difficult, often have to go down 2 and up 1, but never really sure what gear you may have found. All part of the fun riding an old bike. If the 36 Ajay is a problem, get a veteran with no gears or clutch. After that you'll feel better with the 36 AJS. If your gearbox sprocket ever comes off. You should find you cannot see the thread to screw it back on. Put the gearbox in gear, then the shaft will pop out so you can get the nut on.
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