fork tube thread size

[james]

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

 

[norbsa48503]

James , Get the part # for the top bolts (Fork cap) to some and find that # on this site:
http://stainlessbits.com/link12.html Mark this site it is very useful.

 

[L.A.B.]

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.

 

[james]

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

 

[L.A.B.]

I have discovered that the thread size is 1 1/16" x 20tpi -- 60deg. thread angle.

That could still be Cycle thread then?

As someitmes Cycle thread in 20 tpi was used instead of the more common 26 tpi?

 

[james]

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.