1953 18S rocker box to head thread size

Tellybelly · Post by **Tellybelly** » Wed Aug 17, 2005 11:31 pm

No it wasn't me! When removing Arfur's head, I found one of the rocker box attachment threads (5/16 Whit spanner size) missing . The bolt had been just placed loosely in the hole by a previous owner! Please can somebody confirm what the actual thread type and size is for helicoil repair. Is it 3/8 BSF ?

It's a fascinating voyage of discovery with a new old bike isn't it.

Thanks

TommoT · Post by **TommoT** » Thu Aug 18, 2005 12:35 am

Graham,
spares list says 5/16" x 22tpi which I guess makes it a BSF 5/16!

Tellybelly · Post by **Tellybelly** » Thu Aug 18, 2005 9:46 pm

Thanks Tom

Tellybelly · Post by **Tellybelly** » Thu Aug 18, 2005 10:05 pm

Tom - Just put my Victorian top hat on and it all became clear. The BSW hex size is 1/4 not 5/16".
1/4 BSW hex = 5/16 BSF x 22 thread.
Thank you indeed kind Sir for illuminating the error of my ways.
I'll take my hat off now.
Cheers

TommoT · Post by **TommoT** » Fri Aug 19, 2005 12:23 am

Ofcourse, something stirred in the back of my head too! Being brought with the metric system, I am still not totally comfortable with Whitworth and all its' intricacies. The difference between bolt and hex diameter also slipped my mind!