BSA 1920 L pattern screw size

[Phil Russell]

I am resurrecting a 1920 BSA L pattern (L11659). Does anyone know the thread size for the loading tap cover? It currently has brass bolts that are a 'proud' fit but I cannot size the thread ... they do not fit any dies I have. All pictures I have show flush fitting bolts.
Cheers, Phil

[inproved]

Hi,

Thread size...for BSA's....Wait for it..hardly believable....It's Otto Bicycle....26tpi or 37tpi... Now then it's a problem....

Regard's

Inproved

[torrens]

Hi Phil, if it's 26tpi as suggested by Inproved then dies (and fasteners) are easily obtained, Cycle thread was used for many decades by BSA for guns, cycles and motorbikes. If it's finer pitch then it might be a problem. atb Torrens

[inproved]

Hi,

Re Screw Size...BSA's....Pre-War and Pre-1st World War...

The Dia is 165 dia..screw size 37tpi Cycle Thread.....For Side Plate.and even for Trigger Guard the same 37tpi...Some of the other threads are 26tpi...

Regard's

Inproved

[Phil Russell]

Thanks all ... helps a lot.

And for a useless bit of information: I think Raleigh used 26tpi for their cycle bottom bracket threads up until around 1960 when they switched to the standard 24tpi. More interestingly though ... the higher end cycles from the Raleigh stable had used the standard for many years before that.

Cheers, Phil