I recently came across the following attachments within some of my files which I'm happy to share here. It relates to BMC's parts information on Nuts/Bolts/Screws/Washers and its coding thereof found within Parts Catalogue pages.

The prefix details the type of part (bolt/washer/nut/screw), thread & finish. The four (4) suffix numbers detail size: The first two numbers represent diameter in sixteenths of an inch, the second two, length in eighths of an inch.

e.g. HZS507 [Front sub frame rear bolt]
HZS = UNF thread
5 = 5/16" diameter
07 = 7/8" length



Apologise if this information has already been included within these pages but hoping it is useful information for those wishing to undertake an 'nth' degree correct nuts & bolts re/placement within their restoration or otherwise.

Regards

Frank

Attached Nut codes

F

Thanks for these lists. Very useful and will print a copy.
But every so often the parts lists don't use these codes and have other part numbers from somewhere else.

Random example:
"SE604051 - Phillips head screw, top hinge to door"(the one you can see when you open the door).
But using these tables it should be something like PMZ410 (approx - I'm not sure of the length of the screw).

Why the differences?

Bill I must admit I have not seen or referenced the number which you refer in any of my publications. Where is this part no. reference taken from? These supplementary lists are (generally) referenced against the PUB / HYL / AKD Parts Catalogues.

With my book handy, the phillips head screw you refer is 3/4" length - "HZS406"

F

...I'll add - like most of the BMC documentation there are inconsistencies. Your PMZ reference is listed within the earlier 1056M Parts Catalogue, and from the recent attachments indicates it as a recessed phillips head.

I have cross-referenced from PUB1052 which is a later publication and it details HZS - a round head and not countersunk...

F

I was only trying to say that parts catalogues are not always consistent in their use of standardised codes.
My "random example" of a 1/4 UNF panhead screw for a mini door hinge should have been PMZ prefix, but according to Mini Kingdom's parts catalogue it is SE604051. Where do these other part numbers come from when most of the fasteners are predictably labeled?
Wouldn't "HZS406" be a hexagon-head screw?

Bill - firstly my apologies, I did get ahead of myself there... you are correct and I incorrectly referenced 'screw' without looking into hex head... PMZ it probably is at 3/4"

I would think that after market businesses detail their own parts referencing, albeit with a cross-referencing to the BMC Parts Catalogue

I don't quite understand either.
With a standard code system you can tell from the parts catalogue what size of fastener you need without having to buy through a specialist supplier.
Thanks again for the post.