Wishbone Part Number Mystery

[Detonator]

I was cleaning up a '40 passenger car wishbone getting ready to paint, when I noticed the Ford Part Number on the yoke: 78-3412-M38. The M38 is a little hard to read, but on the other yoke (which is really hard to read) it looks like M39.


These numbers don't appear anywhere in my "bible." Could this be a "yoke-only" repair piece?

[V8COOPMAN]

I BELIEVE that M38/M39 will more than likely have to do with the forging process of that particular forging rather than an identifier. DD

[36rgtop]

Most likely the left and right PN that when welded together with the other components make the 3405 assy.

[34PKUP]

Yep! and the ball probably has it's own part number and was not offered as replacement parts, thus no listing as separate parts.

[Detonator]

So maybe these were “internal” part numbers? I figured the M38 and M39 were right and left... so whoever was assembling the wishbone wouldn’t end up with two left shoes.

[V8COOPMAN]

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Just to add to the unknown, ANY year FRONT wishbone is known as a "3405 assembly", with a prefix describing it's FIRST year of application, as in this case a "78A-3405". The "78" denotes 1937 model ('37-'40) and the "A" denoted "passenger car and light pick-up". DD

[Carl]

Originally Posted by V8COOPMAN

Just to add to the unknown, ANY year FRONT wishbone is known as a "3405 assembly", with a prefix describing it's FIRST year of application, as in this case a "78A-3405". The "78" denotes 1937 model ('37-'40) and the "A" denoted "passenger car and light pick-up". DD

I believe the “M” indicates the outside manufacturer of this particular piece. I forget which co. M stands for. They made tools, also. David R could enlighten us.

[barnfind08]

Moore forge

[DavidG]

As 34PKIP suggests, Ford part numbering system was not primarily used for creating identification for service parts, but rather as basis for an orderly process to design components for the production of vehicles. Every fastener, paint, sub-assembly, and assembly was assigned a part number at the design stage which was retained throughout the service life of the vehicle and beyond. If you were to look at a copy of the drawing of the subject part or any other components made up of multiple pieces at the Benson Ford Research Center in Dearborn you would see all of the part numbers for all of those pieces. Often only the whole assembly was provided for service and therefore the part numbers and the names of their subassemblies/component parts do not appear in any service parts catalogue.

As for the subject part number in this case, it seems to depart from the usual Ford numbering practice of a numeric basic number (the 3412) preceded by the model year prefix for which it was first used (78 in this case which as V8COOPMAN notes is 1937) followed first by a letter starting with 'A' and continuing through the alphabet to account for all the design variations that existed for part number 78-3412. If there was more than one supplier making the part in question, a number was added after the letter suffix.

What is odd in this particular instance is that is highly unlikely that the there were thirteen design variations of this part that the 'M' would normally represent, let alone 38 or 39 different suppliers. One can only conclude that those part numbers are hybrids, likely those of the supplier. Moore did mark most of the forgings it made for Ford with an 'M', most often encountered on the hand tools they made for Ford's tool kits. It is as good a theory as any to explain the part numbers' partial nonconformity to Ford's usual numbering practice.

[Detonator]

Thanks Fred and David, as usual I'm humbled by your knowledge of our cars.

[rotorwrench]

The numbers meant something to those that were involved with the manufacture of a part. As was mentioned, it could be for assembly ID or tracking. It also could have had something to do with the forging dies. Cast parts and forged parts generally always have some unidentifiable numbers or letters to folks that had no part in the original manufacturing processes.