I’m going to replace most of the nuts on my M20 with stainless ones. There’s a website here in the Netherlands that has a wide selection of WW, BSF and CEI nuts and bolts: website www.montagetechniek.nl (Unfortunately only in Double-Dutch, but Patrick will certainly be able to communicate in English).
I made an inventory of all the nuts in the WDM20 parts list, and in the best British traditions there is a multitude of different part numbers for all the sizes. For instance, for 1/4" nuts there are 14 different part numbers: EA80, EA82, EA111, EB102, EB106, EB108, EB113, EB201, EB171, EB664, M202, M263, K234B, 15-447!
For some I can understand; for instance EB102, “Kickstarter return spring anchor pin nut” is a thin nut, but in what differ the other nuts from plain BS ones

email (option): viaconsu # planet dot nl

Hi Hans...I don't know the answer to your question but there could be material spec. differences for various applications that might call for identification for some of them. The thin nuts are called 'half nuts'.
It may be that they just gave a specific number to each nut purely because they identified each part of the bike individually in the parts lists..Ian

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

Yep I would think that apart from a slim nut or reduced hex nut. A 1/4" BSC nut is a 1/4" BSC nut. I also think most nuts on an M20 have a flat bearing side and a chamfered side. Perhaps there are differences in the chamfer profile. Ron

email (option): ronpier@talk21.com

Nuts with a 'flat side' and a 'chamfered side' machined from barstock were the 'standard' pattern in the motorcycle applications..Ian

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

Hans try this site: http://www.stainlessbits.com/link12.html

it's been invaluable for me as i'm mid restoration of an M21 and a B33, it's very time consuming rummaging through the Spares/Parts Manuals and cross referencing that with the web site but it's a hell of a lot easier then measuring up where a nut, bolt, washer, spacer or stud needs to go and what size and standard they are.

Hope that helps! -nick

Thanks Nick, but I know this list. Unfortunately, it gives no information about the nuts with letter-prefix (like EA.., EB.., M.. etc. in my 1944 parts list.
But I don't think that a not entirely correct nut will have much influence on my bike's behaviour...

email (option): viaconsu # planet dot nl

Hi guys,

I've been making drawings of all these studs, nuts, and the varients of head sizes and thicknesses.

Yes, it is tedious. I'm sorting things as I go aling, and hope I can get some help from you as a cross check. I will then publish the list and drawings here on forum.

This is real rivet counter work, but should be done for the sake of the bikes.

I'll send my list to you for annotation if you will help in this.

Cheers all

email (option): britool51@hotmail.com

Just send me what you have Robb, I'll add what I have done so far!

email (option): viaconsu # planet dot nl