Gearbox change for 38/26

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Gearbox change for 38/26

Post by trophy »

Advice please. My 1938 350 AJS38/26 has a Burman type H gearbox fitted, the one with the clutch operating gear inside the outer cover. Is it possible to replace it with a later Burman box? And if so how difficult would it be?
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dave16mct
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Re: Gearbox change for 38/26

Post by dave16mct »

Yes it is possible. I have a friend with a Silver Streak 38/26SS which has a CP box fitted. You could use a WD CP box, engine plates and rear sprocket giving you a 5/8x3/8 rear chain.
Dave.
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Rob Harknett
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Re: Gearbox change for 38/26

Post by Rob Harknett »

It sounds like you have the correct, rare, H2 Burman box. Used only on 250 & 350 1938 and 250 only 1939. I have seen these years with wrong, later, CP boxes. From memory I believe the rear chain in 38 changed, so a CP sprocket would be ok. Prior to 1938 the rear chain was the same size as the primary chain. I have no idea how easy it is to get a CP box to fit within the plates, get chains aliened & get primary chain adjustment parts fitted.
May be you could get someone with the wrong gearbox to swap for your correct one? That person would also know how to get it in. Perhaps swap with his bits to bodge it in for your correct bits. Is that what you really want? Wrong box bodged in instead of all being correct.
Just noticed Dave's comment. His friend may like to swap boxes and bits to make his bike correct.
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Re: Gearbox change for 38/26

Post by trophy »

Thank you Dave and Rob. I will give it more thought. Seems like it could be more problematic than I first thought. Thanks a lot both.
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dave16mct
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Re: Gearbox change for 38/26

Post by dave16mct »

Is the bike together or in bits?
Dave.
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Re: Gearbox change for 38/26

Post by trophy »

Hello Dave. Bike is all together and on the road.
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Re: Gearbox change for 38/26

Post by trophy »

dave16mct wrote: Thu Oct 14, 2021 12:24 pm Is the bike together or in bits?
Dave.
Hello Dave. My previous reply to your question should include the reason I wondered if the CP box could be easily used. The splines on the gear selector quadrant have seen better days and I cannot source a replacement, nor do I know of any company that can recover splines.
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Duncan
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Re: Gearbox change for 38/26

Post by Duncan »

You may already know that the CP box was fitted to the 1939/26 so yes it can be be done as Dave has already said, it was also an upgrade that was carried out to earlier bikes in the post war years when there were plenty of surplus CP boxes and other parts about.
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