Topic: Spring Shackles ~noted markings on 11/2/66 built San Jose

[67gtasanjose]

I recently ran a pair of good (light surface rust) original single exhaust spring shackles through Evaporust and made these observations: (note: pay particular attention to the extra note on the "nuts")

*Shackle side with studs: One had a letter "C", other had an ""E" stamped on the insides of flat steel

*Shackle plates: Both had "C6DA" stamped on the insides

*Nuts: 3/8-24 Top-Lok (looks like AMK B-12871)

Nothing particularly noteworthy EXCEPT for the reason of my post, I noticed two of the four original nuts have ONE of the sides marked with a BLACK paint or marker.   Only two of the four nuts have this marking and it is clearly NOT overspray from any repaint (I have noticed some minor overspray of body color elsewhere on these shackles from repaint, it is clearly dark green, and these marks are clearly black)

I am thinking these marks are an inspectors mark of a sort, any thoughts or other notes from others on similar findings?

[J_Speegle]

Haven't seen and/or noticed those will have to keep an eye open for other examples to establish a patter and support if it was done. But with your sighting will look for it

[specialed]

I found the c6da stamped shackles only on cars on west coast never on Dearborn cars

[67gtasanjose]

I found the c6da stamped shackles only on cars on west coast never on Dearborn cars

Yes this is a San Jose built on November 2, 1966, 67 example

[ruppstang]

I cleaned up some shackles off a 5-11-67 SJ car and also found a black mark on the nuts. They had the C6DA marking but what I found that was odd was the different color of the steel on the caps as compared with the body half. The caps almost looked zinc plated and both sides were the same. Has anyone else seen this?

[67gta289]

+1 on C6DA for SJ cars.

Marty, what are you referring to with the term "caps"?  To me each shackle has a stamped steel piece, two threaded studs, and two nuts.  Five pieces total, excluding of course the rubber bushings.

The studs are pressed in, and the shaft is "flute" like front coil spring saddle bolts.

It looks to me that the studs from both ends ("cap" end and threaded end) are the same darker color.  Since they are one stud, the same finish would be expected.

The ones that I see are all one color...rust

[J_Speegle]

..............The caps almost looked zinc plated and both sides were the same. Has anyone else seen this?

Nope

[ruppstang]

+1 on C6DA for SJ cars.

Marty, what are you referring to with the term "caps"?  To me each shackle has a stamped steel piece, two threaded studs, and two nuts.  Five pieces total, excluding of course the rubber bushings.

The studs are pressed in, and the shaft is "flute" like front coil spring saddle bolts.

It looks to me that the studs from both ends ("cap" end and threaded end) are the same darker color.  Since they are one stud, the same finish would be expected.

The ones that I see are all one color...rust

In the picture of the two together you can clearly see the cap or half the nuts hold on is a lighter color metal. I just thought it was odd.

[67gtasanjose]

+1 on C6DA for SJ cars.

Marty, what are you referring to with the term "caps"?  To me each shackle has a stamped steel piece, two threaded studs, and two nuts.  Five pieces total, excluding of course the rubber bushings.

The studs are pressed in, and the shaft is "flute" like front coil spring saddle bolts.

It looks to me that the studs from both ends ("cap" end and threaded end) are the same darker color.  Since they are one stud, the same finish would be expected.

The ones that I see are all one color...rust

Marty & I spoke on the phone a week or so back about this. When we spoke, I didn't recall anything different in the coloring of the stamped steel sides of the shackles. I have since this post, looked again at them this morning. Without any "rust" discoloration like John speaks of, I concur with Marty on the different coloring of the metal (though mine seem to only be slightly different in color). My original examples have been run through Evaporust and simply wiped off with a clean, dry rag, no "buffing" of the finish at all yet. I imagine using a bit of 000 steel wool, the color difference might be more noticable.

[ruppstang]

Richard mine like your were just run through Evaporust and no buffing.

[Bob Gaines]

The slight difference in shade may have to do with heat. I am convinced it is not plating . I wouldn't think so but there may have been heat associated with the process of pressing in of the heat treated hardened splined studs enough to change the shade.

[WT8095]

The slight difference in shade may have to do with heat. I am convinced it is not plating . I wouldn't think so but there may have been heat associated with the process of pressing in of the heat treated hardened splined studs enough to change the shade.

The studs would be darkened from heat treatment. It's the natural result of heat treating in the presence of oxygen (i.e. not an inert-gas or vacuum heat treat). Pressing the studs into the other component would not generate enough heat to cause discoloration.

[Bob Gaines]

The studs would be darkened from heat treatment. It's the natural result of heat treating in the presence of oxygen (i.e. not an inert-gas or vacuum heat treat). Pressing the studs into the other component would not generate enough heat to cause discoloration.

"I wouldn't think so" as I indicated in my post. The metal was darken by something . It may however be some kind of by product effect associated  along the way in processing in some way or another  that I am not aware of. That is what i was throwing out there SINCE there is no other reasonable explanation i can think of. For instance if a hot stud was pressed into a metal plate it could raise the temperature of the plate enough to effect the shade of the metal. I am not saying that is what happened just proposing a possible scenario.

[WT8095]

"I wouldn't think so" as I indicated in my post.

I was backing up your assessment, not disagreeing. Sorry if it didn't sound that way!

[1967 eight barrel]

My Dec '66 manufactured Shelby also has the C6DA stamped on the non-studded side of the shackle plate.

                                                                               -Keith