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Does anyone know how BMC made up the lettering that we see on castings and forgings?
ie; 12G940 what does the 12 refer to, the G and the 940 ?
I have experimental parts of similar types but with different casting numbers, and wondering why this should be so.
29Dxxx and 22Gxxx very nearly the same component, how were these numbers decided on?
It would seem the first three digits would refer to the type and from then on simply a component number.
Anyone got any definitive answers please?
Cheers

Dunno if this is of much help, I have lifted it from Winabbey's post here http://www.mokesinc.org/index.php/topic,8716.75.html

winabbey wrote: Spider - you probably know what I've included below but there may be others interested in how BMC part numbers are created. The following is extracted from the BMC Australia Standards document - A15 (Part Numbering System) - last update April 1972.

The format is aaannnn (i.e. three alpha character prefix, followed by four numerics).

The first character of the prefix is A to F for mechanical, and H to Z for body (omitting I, O, Q and S). Allocation starts at A (for mechanical parts) and moves through B, C, etc. as numbers are used up.
The second character is used to indicate the Company or Branch in the organisation which originates the drawing. For BMC Australia it is Y.
The third character indicates the model range for which the drawing was first created. Valid character are A to L, omitting I. Interestingly, E isn't used, although may have been added at a later date, or been used for experimental parts. It doesn't appear in any parts book, price book or supersession list.
The four numerics are 0001 to 9999, sub-divided into groups to indicate the section of the vehicle.

So AYE3067 is a mechanical gearbox part with the drawing created by BMC Australia.

The two cylinder engine had castings starting with 19D

Could the D be for development ?

A lot of cooper s parts are AEG which I believe has some reference to morris engines

Also noticed that Austin Healey 3000 use AEC and they can from same factory

707 seams to be for special competition parts , also made at morris engines

All the above are for engine parts

I was told by ex weslake man that d signified "development". all prototype / non production heads i have are assigned a d.

maybe it designates a part's functional success. i.e G = Gold! D = Dogshit, or Destroy!

Spider, thanks for the effort but that relates to part numbers, not casting numbers.

251 ENG, you may well be right about the "D", my first "Ant" box has casting numbers 19Dxxx, I think this box came from the '66 Ant prototype that looked like a halfway house between Moke and Ant, very developmental.

Will Grant, you too maybe right, especially about the dogshit! The above box is not well cast at all. I think it was cast in kitty-litter, not sand!

So come on, how were casting numbers made up?
I'll post some Ant casting numbers up tomorrow.
The reason I ask is because there seems to be two batches of Ants with differing details, and differing casting numbers. I'm trying to establish if they're different years, different departments, different factory sites. They seem to have made changes for no obvious reason.......

Prototype / Development and Production ?

We're really not sure what's going on! All the Ants we have on record thus far are of the same type as per the one at Gaydon. One of the Ants I have has different body pressings and different casting numbers on suspension and transmission components with subtle minor differences.
We thought all 24 were built at the same time in the same place. It now seems not.
The workshop manual which is dated '68 has drawings of both types! So that's no use in tying it down.

Someone somewhere must know how the numbers came into being, i think I have more chance of having this verifed than directly finding answers about the Ants themselves.

Have an ask around please chaps, this is losing me sleep!

you have to remember that with the uk derived part numbers (ignoring the aus listings shown above which appear to have some common sense in them, but they did come from one factory, at one time!) that bmc was using part number systems from more than one source, and they just all got a bit jumbled up when all the various firms came together. they didn't really sort it out until the 1980s when some sense seamed to come back. i.e with part numbers starting with 'dam', 'cam' etc.

if you look at some of the mid 1950's parts books for stuff like big healeys, a70's etc, there is a far clearer stream of part numbers, with a far more sensible 'blocks' of numbers with clear letter starts that could give a large hint as to what they might be for.

if you get the collection of 1950's books its possible to cross reference the start point of numbers that came into existence far later and sort of see where they came from, i.e a number that starts '3h' will have originated from one sequence of one particular part for one car.

its not a boring subject at all, I love part numbers, in fact a true anorak should be able to part number a mini front to back from memory, go on try it, its easy

Guru, can you tell me anything about the following starts to part numbers?
22Gxxx
19Cxxxx
Any idea which factory is which, dates, or just about any info at all, no matter how insignificant !
Cheers

22G are mechanical rather than body parts.

We don't have 19C part numbers on production UK Mini's.

I have seen somewhere many years ago (possibly at Gaydon) a factory part number book with a guidance note on the issuing of part numbers. The numbers were just a numerical sequence so if 24A1402 was for a Mini there is no reason to think that 24A1403 was for a Mini, it could be for any model that BMC produced at the time.

As a general rule for Mini's:

AEA/AEG = mechanical

AKD = printed matter

AUA/AUB/AUC/AUD = fuel system

BTA = suspension & steering

The vast majority of items with a G in the part number (so whether AEG or 8G or 22G etc) tend to be mechanical components.

Ok Simon, that's starting to move it forwards somewhat.
Considering that I'm talking BMC prototypes/development vehicles/Pre-production vehicles, in your opinion would 19Cxxxx be further back in the prototype stages than 22Gxxx which is taken from what is classed as a pre-production vehicle.
Did any particular department have sole use of prefixes?
Did any particular plant have sole use of prefixes?