Quote: Are you comparing NOS samples to assembly line, factory issue parts? If so, you will find that assembly line metal parts were usually not coated or protected due to their immediate use in production. The NOS parts that could/would end up on a shelf for months at a time usually had some form of protective coating in anticipation of not being installed for long periods of time. I hope I was clear as to the parts you had access to years ago. Were they replacement NOS pieces or were they manufactured as assembly line parts?
Dave
If any of these have ever turned up as a "lunch box" type part, that is what I would like to see as it would settle this issue once in for all. To coat a bare metal part for protection because it isn't going to installed on a car coming down the assembly line, instead to go out and sit on a shelf as a replacement part makes all the sense in the world. However why would they have gone to the trouble of ecoating a raw casting prior to manufacture, just on parts that were destined to be replacement parts? It would have been far easier just to take a pallet of just assembled master cylinders that were slated to be replacement parts and spray a coating of paint on them for protection. That is what they did with all the disc brake Mopar cylinders. E coating is significantly more expensive than painting. Also, since the casting is machined after the ecoating, surfaces such as the outlet facings, piston retainer screw boss face, and firewall side of the flange are machined and left raw metal, which of course is going to surface rust. It just makes no sense that they would do this. And I worked in this industry and know firsthand that making ecoated parts for replacement and bare metal for assembly line would not be at all favorably viewed by the beancounters, QC, process engineers, industrial engineering or the actual workers in the assembly line. Here is a picture of a 134th day of '68 dated example off a SW car. When I started to clean the surface rust away there was some ecoating left.
