BSA M20 Rear stand bolt seems to have two numbers.
24-6055
24-6058

And just to make it tougher, I've just found 66-4769

You can't trust the pattern bolts as I'm convinced, they are all wrong.
Could it be as simple as different hex sizes?
Help! anyone?

Mark

email (option): pes.sales@btconnect.com

My illustrated parts list for the RAF contract that ran from May 41 to Jan 44 quotes 2 x 24-6058. 66-4769 seems to have a split pin drilling as for a castellated nut? Ron

email (option): ronpier@talk21.com

66-4769 is in the 1940 illustrated civy parts list, but the nut doesn't look castellated. And a different part number for the bolts in 1939 15-6096. Ron

email (option): ronpier@talk21.com

I do wonder about the accuracy of some of these parts lists Ron.
I found some dimensions for the 66 bolt and it wouldn't fit a latter stand than 1940
As you mention it is also drilled for a split pin.
The first listing I've found for the 24-605? was for a G14

Mark

email (option): pes.sales@btconnect.com

Bsa used many rear stand bolts over the years 24- 6058 is from 1927 25/32” Hex
15-6096 is a Blue star type.
These are the origins of the parts numbers you quote.
66 parts numbers don’t originate until 37 and Val Page.
Harold Briggs was a better designer.


G models changed little over 12 years and therefore used many early parts

Thanks Darren, 24-6058 and 24-6055 is the biggest mystery.

Mark

email (option): pes.sales@btconnect.com

Hi Darren. 24-6058 are the bolts listed in the RAF M20 list. contracts C10655-C14052 (1941-44)and also in the list for S12424 (1941--)

Ron

email (option): ronpier@talk21.com

Thanks Darren, Ron.
I didn't go back as far as 1927, I do wonder if they are one and the same?

Mark

email (option): pes.sales@btconnect.com

Strange about that hex size 25/32" (which is near as dammit 20mm) So far I've only ever found that size spanners and sockets in AF? Ron

email (option): ronpier@talk21.com

It is a popular size on a M20 Ron, it has made me wonder.

Mark

email (option): pes.sales@btconnect.com

People have argued with me that it can't be a "Whitworth" hex size, but it clearly was used by BSA quite a bit. I think they expected you to use the special BSA spanners. But I have 25/32" AF sockets and spanners, plus 20mm, so I don't need to use those clunky old tools which are just nice to collect and look at. Ron

email (option): ronpier@talk21.com

Ron
It is definitely 25/32” others are wrong, also the BSA box spanner 15-832 used from the 20’s to post war is 25/32”.

There are 25/32” nuts from the teens.

A lot of nuts and some bolts actually Originate from the teens.
The earliest bolts and nuts have EB part numbers, same with K M EA B prefixes.

So basically a M20 is basically a collection of left over parts from the teens twenties and early thirties.
M202 are my rear axle nuts on my 1915 H model
EB 121 are my back stay bolts
Ea 80
Ea 82
EB 113
EB 102
EA 76
Just to name a few , come from the teens but are still used in the 40’s.
All these are also on my Vtwins , slopers, Blue stars and every other of my 20’s and 30’s models.

Why would BSA not keep using the same parts across multiple models and decades.

27-parts numbers originate from 250 models
15- 350 models
24-500 and 770 and 1000
31-30’s v twin

This is not always the case, but a great many do hark back to the early years of BSA.

I heard a rumour that 25/32” actually came from the Gun side of BSA.
But I have no proof.
But possibly BSA did this so you had to but their parts.

Stanley tools use an obsolete thread from the 1850’s, to force you to purchase their parts, rather than the superior English Record Tools parts.

Thanks for that Darren. Very interesting indeed. Ron

email (option): ronpier@talk21.com

Looking at the list of DME circulars again

Immediate action

B.147 8/11/41 Bolt, rear stand. Locknut for bolt. BSA

So the change came from the War Office and presumaby BSA drilled all the bolts for a split pin from this time on, but that doesn't necessarily mean the part number changed?

I'm glad I don't have a 1940 M20, how would I decide between safety and originallity? :grinning:

email (option): robmiller11(a)yahoo.co.uk