Hi everyone,

I am wondering if it is possible to find replacements for original nuts and bolts. We have a '54 B31 and I have managed to break several of the bolts that fit the panniers to the racks. I assume they are BSF / Whitworth. I also want to find some other nuts and bolts that we need to replace. How do people who are restoring incomplete bikes for example find the correct fittings? Or do you just replace with the closest metric alternative?

Thanks, Michael

Try not to use metric if you can help it, simply because it means that you have to carry 2 sets of spanners in your toolkit. Most of the BSA ones you need will be cycle thread at 26 teeth per inch, on 1/4" this equates to the same as BSF, most are available from specialist suppliers or from eBay. Some of the larger sizes use 20 tpi as the 26 tpi are too fine for that particular application. If you aren't sure what sizes you need please just ask on here as someone will know.

email (option): davmax@ntlworld.com

You can get the correct cycle thread fixings from here quite cheaply. They are English made and zinc plated.

http://www.nookysnuts.com/

Ron

email (option): ronpier@talk21.com

Thanks guys, that's great. I'm glad I can get them. That supplier is on holiday at the moment. Can I upload a picture here to see if anyone can identify the nuts and bolts or should I describe them? Then maybe I can find them on ebay. Not sure how to upload a photo though?...thanks!

Bolts are measured 'under the head'..(the shank length)..Thread diameter gives the size and thread type the pitch of the thread etc. Additionally in the case of Cycle thread you must specify whether the thread is 20tpi or 26tpi as required. The head size will automatically match the rest once those specs. are defined.

'Bolts' have an unthreaded section on the shank..

Threaded all the way to the head they are known as 'set screws'..

So,for example a 5/16"x 26 x 1", Cycle thread, hexagon headed bolt would be...

A Whitworth form (size)Hexagon head.
1" long under the head.
5/16" Cycle thread at 26 tpi.
Would not be threaded for the full length.

Screws normally have a 'filister' pattern head...this has a slightly domed top. With a screw driver slot screws are known as 'cheesehead screws'...(not 'panheads' which have a different form and crucially, a larger head diameter...
So you are looking for cheesehead screws with a filisteter head...If you want them fully threaded they are 'full thread'.....
Hope this helps...
'Non standard' fasteners, such as the anti drain valve fitting in the timing cover for example, will have to be sourced by BSA part number and description if needed and will be more difficult to find generally and in some cases not available.....Ian

email (option): ian@wright52.plus.com

That's great, thanks! If I'm not sure how do I upload photos onto the forum to check? Thanks, Michael

You have to do it with a Photobucket account and some computer wiz kid will probably tell you how. Or you can email them to me and I'll post them until you can do it yourself. Ron

email (option): ronpier@talk21.com

Various thread forms have different angles.
BA (found on electrical equipment )has 47 deg angle.
BSW and BSF has 55 deg angle
BSC, Metric and UNF has 60 angle.
BSA use mostly BSC, BSF, BA and a few BSW, but never metric or UNF
You can mix thread angles ONLY if you cannot get the original replacement AND the fastening is not high load bearing.
You must never mix different pitches. Note that 5/16" BSF has 22 TPI and 5/16" UNF has 24 TPI. The nut may fit but will be tight.

When all else fails, use threaded rod cut to size and corresponding nuts. I have brazed nuts to threaded rod, machine the nuts round and machined screwdriver slots.

Download the thread tables available from many sources on-line and get yourself a thread guage.

To get your bike on going, its OK to use metric nuts and bolts. You should file off any metric markings and change them if and when you get the correct replacement.

Use a thread lock compound. For hidden nuts (under mudguards etc, you can also use nyloc nuts.

email (option): pvlietstra@gmail.com

Thanks for all the help guys! That's great. I'll get myself a guage and a ruler...all the best