[TR] How to tell the size of bolt or setscrew from the part number?
mdporter at dfn.com
Wed Jun 17 15:59:19 MDT 2020
On 6/17/2020 2:07 PM, Sujit Roy wrote:
> Hello Don,
> I have the standard triumph hardware catalog and have to refer to it
> all the time. I do see some sort of sequence with the last digit, but
> other places that sequence is off.
The system has to be designed to accommodate this, and I don't think
either the S-T or B-L systems do. And most manufacturers do this
differently. For example, GMC simply assigns part numbers
sequentially. An engineer needs a part number for a new a/c part and
goes to the parts book, creates the next new sequential number and a
description. The next engineer comes along and needs a new suspension
part and so the next new number, one number apart from the last one, is
a ball joint. Part numbers for the component parts of an assembly are
usually assigned by the people writing the parts manuals, and that's
where you'll often see consecutive part numbers for similar part types,
simply because they're doing breakdowns of a purchased assembly all at
I understand the pitfalls of this system since I wrote parts manuals for
a GMC product for quite some time. One digit off in ordering fifty
screws, and you could end up with a couple of pallets of a/c evaporator
motors (that's actually happened). And, lazy manual writers never
checked to see if a number had already been issued for a part used on
more than one type or style of purchased assembly from a vendor, so the
number of part numbers for that part simply multiplied. These never
showed up in the electronic parts management system used to create the
bills of material for each vehicle, since that was composed of top-level
parts only, so I had to create my own searchable database to purge them.
VW, for a very long time, has had a descriptive part number. IIRC, the
first number is the vehicle type (1 for bug, 2 for bus, 3 for
squareback/fastback, 4 for the 4lls and 412s, etc.) in which the part is
first used, the second is a two-digit code for where on the vehicle the
part was first used, then a code for part type, then a two or three
digit code for size and then a sequential number indicating that it's
the xxxx part of that configuration used in the manufacturing history.
As VW expanded its model line and options, they appended an -xxx number
to a part to indicate its use for trim or color purposes.
Ford uses a similar system to VW, except, as I recall, it's alphanumeric.
Never let anyone drive you crazy when you know it's within walking distance....
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