The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: KeithJ on 11.04. 2013 08:30
-
Appreciate some input from those with a font of knowledge. I know some heads are A/F sizes but I am being told some UNF threads have been originally used. I don't think this is so. Am I wrong?
-
Hi Keith, my experience has been either Whitworth or cycle threads (which are typically whitworth head sizes anyway), but with a few BA's thrown in for good measure!
I know the guys on the forum can be much more specific about whats used where though, but I dont think (early) British bikes ever used UNF at all.........
-
Hi Keith.
UNF and UNC are imperial threads, and were common in the engineering industry upto the change to metrication, I was brought up with these threads in the 60s, can confirm they are not used on BSA,s as they left the factory. That,s not to say some of your bike has been modified using these thread,s by previous owners.
-
Thanks for the replies which confirm my understanding.
ATB
-
The later A50/65's are a minefield of threads. UNF & UNC as well as some cycle and whitworth.
Cycle, Whitworth and BA on A7/10's.
Cheers
-
And we won't mention some of the threads that Amal & Lucas used!
Trev.
-
You might find some "period" aftermarket parts like pillion footrests or silencers etc are UNF/UNC.....