Allen Seat Bolt

Excel

Excel

Retro Guru
am a bit stumped and was hoping someone could advise as I'm currently rebuilding a 1960's frame that is missing its integral seatbolt (screws straight into the fastback seat cluster without the need for a nut) my question is that a 6mm is just a bit too narrow, 8mm is too big leaving me to think it must have an Imperial thread, I have tried offering a standard seat bolt to see if that screws in but that is also too big so I was wondering were these integral seat bolt threads standardised back then or is a trial and error process in trying to find the right threaded bolt? (M7 bolts don't appear to be available option)
would appreciate any help
Griff
 
Back in the 70's we had to go back to the builder or try and find a suitable bolt as quite a few were different. SABA did some titanium replacements and another (who's name escapes me) did a range of stainless steel ones.

I wonder if Ceeway does them ?

Shaun
 
I know what you mean. My Dave Russell has a similar thing and I never discovered what the REAL thread was. I just found a steel cap head allen bolt of the right diameter and sort of re-tapped the frame by screwing it in and out a little bit at a time.

Not recommended, I suppose I was lucky not to completely ruin it!
 
Maybe if you have the binder professionally tapped? Very old frames with long gone standards and fittings can be the most frustrating part of a quality restore. Which is why I am so pleased when a frame comes with the proprietary bits in place. Just try sorting a seat binder for a 50s Legnano.


Steven
 
Just had a look on the ceeway site, can't see them but would be worth an e-mail :) i wonder if the thread is the same as a brake centre bolt? Might have to re-tap to a modern metric size as mentioned

shaun
 
My best guess is 1/4 inch BSF, 26 TPI. The tapping size is 5.5mm, if you happen to have a 5.5mm drill it should just go through the hole to check the size.
A 6mm x 1 would be a very loose fit, but would feel it was going in.
Keith
 
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