Author Topic: burman thread size  (Read 1023 times)

Offline chaz

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burman thread size
« on: 27.10. 2010 08:48 »
I know not drectly BSA but does anyone know the size of thread on the  mainshaft of a Burman gearbox
clutch end, its 5/8 guessing 20tpi but what BSF,BSW?
actually on a Ariel Huntmaster
also is it acceptable/wise to get a damaged thread welded and re cut?
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Offline Goldy

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Re: burman thread size
« Reply #1 on: 27.10. 2010 10:35 »
I don,t know about Burman gearboxes, but 5/8 BSF is 14 tpi, BSW 11 tpi. I would think it.s BSC which can be 20 or 26 tpi.
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Offline bonny

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Re: burman thread size
« Reply #2 on: 27.10. 2010 12:05 »
I know not drectly BSA but does anyone know the size of thread on the  mainshaft of a Burman gearbox
clutch end, its 5/8 guessing 20tpi but what BSF,BSW?
actually on a Ariel Huntmaster
also is it acceptable/wise to get a damaged thread welded and re cut?

if you weld it you might (read will) bend the shaft with heat distortion , better to turn it down to the next smallest size or replace it , have you tried draganfly ?

Offline dpaddock

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Re: burman thread size
« Reply #3 on: 27.10. 2010 14:22 »
If you metal-spray it, the temperatures involved are too low to warp anything.
Alternatively, you could probably recut the thread to 9/16 CEI and still have a good grip if it's not a tapered shaft.

David
David
'57 Spitfire


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Re: burman thread size
« Reply #4 on: 27.10. 2010 19:01 »
It's 5/8 20 for sure. BSC I'd say for the lack of other matches. Problem with turning down is that the clutch push-rod on the Burman is quite a chunky thing and there isn't that much metal to play with if you clean right down to the minor diameter to start again. No chance of getting it back with a die and a new nut?
Faced with the same problem a year or so back, I cleaned things up as best I could, cut the thread just a tad deeper in the lathe and made a new nut a fraction under-size. Hell of a palaver but works fine.
Good luck!
Bill

Offline chaz

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Re: burman thread size
« Reply #5 on: 27.10. 2010 22:48 »
tried thread file to clean out, and thread pitch gauges but as half thread is missing thought best to ask.
currently using a new nut with loctite but looking at a strip down as found a spare shaft.

what I would like for a project bike is a mainshaft for a square four which I believe is around 3/32" longer than a
standard burman shaft.
allways willing to learn
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