fork tube thread size

james

Joined
Aug 24, 2005
Messages
198
Does anyone out there know the thread size and pitch of the threads in the top of fork tubes for BSA A10 / A7 / Goldstar?.
55deg. or 60deg. thread form? Thanks.
James
 
I had already tried checking the part number (65-5331) against that list for james, but the thread type is listed unknown.

However it is very likely to be CEI (26 tpi?) 60 degree thread I would have thought.
 
Thanks to LAB and norbsa48503 for checking this out. I have discovered that the thread size is 1 1/16" x 20tpi -- 60deg. thread angle.
Thanks again.
James
 
james said:
I have discovered that the thread size is 1 1/16" x 20tpi -- 60deg. thread angle.
Click to expand...

That could still be Cycle thread then?

As someitmes Cycle thread in 20 tpi was used instead of the more common 26 tpi?
 
the thread size of 1 1/16 x 20tpi is UNF form, close enough for my purposes -- making a tool to pull the fork tubes into the top yoke, and also to break the taper when removing the tubes. I believe that the difference between UNF and CEI threads is probably the thread form, radius or truncation of the root and / or crest of the thread. When I screwed a 1 1/16 x 20 UNF tap into an old fork tube ( BSA ) a small amount of material was shaved. Thanks for the attention to my question.
James.
 
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