Rocker Molding Retainer Screws finish??? - NCRS Discussion Boards

Rocker Molding Retainer Screws finish???

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • James W.
    Extremely Frequent Poster
    • December 1, 1990
    • 2655

    Rocker Molding Retainer Screws finish???

    Looked through my 1963/1964 and 1965 judging manual and can't find any reference as to what the correct finish is (silver zinc or black phosphate) for the rocker molding retainer screws. This is for my late production 1965 coupe. Picture of the repro on the left and what I removed from the car on the right from my '65 that has been owned by my family for 50 years.

    Thanks,

    James
    Attached Files
    Last edited by James W.; February 8, 2025, 04:33 PM.
  • David B.
    Very Frequent User
    • March 1, 1980
    • 689

    #2
    Do you have a part number?

    Comment

    • Gary B.
      Extremely Frequent Poster
      • February 1, 1997
      • 7023

      #3
      David, James,

      Probably GM 3848300. Based in what I’ve read and seen first hand, repros tend to be zinc. GM examples that came with MOS retainers tend to be yellow/gold dichromate. My guess is that originals were black phosphate or dark, natural. Rich Pasqualone has said black.

      Gary

      Comment

      • Tom D.
        Extremely Frequent Poster
        • September 30, 1981
        • 2134

        #4
        I think... these along the bottom?
        https://MichiganNCRS.org
        Michigan Chapter
        Tom Dingman

        Comment

        • James W.
          Extremely Frequent Poster
          • December 1, 1990
          • 2655

          #5
          Originally posted by Tom Dingman (4889)
          I think... these along the bottom?
          No. There are six (6) total on each side to retain the rocker molding retaining strip. The U-nuts or clips are black phosphate, but I am trying to determine the screw finish. As you can see the repro is zinc plated.

          James
          Last edited by James W.; February 8, 2025, 09:07 PM.

          Comment

          • James W.
            Extremely Frequent Poster
            • December 1, 1990
            • 2655

            #6
            Originally posted by David Bartush (3288)
            Do you have a part number?
            The screw is part number 3848300 and the U-nut is 3846854.

            Comment

            • Gary B.
              Extremely Frequent Poster
              • February 1, 1997
              • 7023

              #7
              Originally posted by Tom Dingman (4889)
              I think... these along the bottom?
              Tom,

              The screws go in horizontally, holding the retainer to the fiberglass. They are not the screws that go up from the bottom, holding the rocker molding to the frame brackets.

              Gary

              Comment

              • Gary B.
                Extremely Frequent Poster
                • February 1, 1997
                • 7023

                #8
                Originally posted by James West (18379)

                Yes, six (6) total on each side to retain the rocker molding retaining strip. The U-nuts or clips are black phosphate, but I am trying to determine the screw finish. As you can see the repro is zinc plated.

                James
                James,

                In the ‘64 thru ‘67 AIMs those rocker panel retainer screws, 3848300, are the exact same screws as for the wiper grills. They are dark, probably black phospahte. Not zinc and not dichromate. If you search the archives for 3848300 you can read what’s been said before.

                Gary
                Last edited by Gary B.; February 8, 2025, 10:21 PM. Reason: Fix typo

                Comment

                • James W.
                  Extremely Frequent Poster
                  • December 1, 1990
                  • 2655

                  #9
                  Originally posted by Gary Beaupre (28818)

                  James,

                  In the ‘64 thru ‘67 AIMs those rocker panel retainer screws, 3848300, are the exact same screws as for the wiper grills. They are dark, probably black phospahte. Not zinc and not dichromate. If you search the archives for 3848300 and you can read what’s been said before.

                  Gary
                  Gary,

                  Did some digging and found a post that discussed them with pictures that match what I have. Looks like what I took off the car last month are the factory installed screws and U-nuts with the "P" embossed into them. Will bag and tag them to be finished on black phosphate. Since we've owned this car for 50 years, I doubt my dad ever replaced them when he had the car repainted in 1977.

                  Thanks,

                  James

                  Comment

                  • Michael G.
                    Extremely Frequent Poster
                    • November 12, 2008
                    • 2157

                    #10
                    I doubt that they are black phosphate, that finish would rust after the first rain in such an application. Fisher Body/Chevrolet had, in those days (and may still use something similar, I don’t know) a black exterior body finish (GM-6138M) that has multiple electroplates, followed by a black paint coating, for such applications. It lasts essentially forever.

                    I don’t know if you can still get that finish, I doubt it, but instead I’d recommend you get the parts cadmium plated, (which will get you much better corrosion protection than zinc chromates) then spray them black yourself (after being on the GM fastener finish committed for many years, that’s what I do). That’ll last longer than you own the car.
                    Mike




                    1965 Black Ext / Silver Int. Coupe, L84 Duntov, French Lick, 2023 - Triple Diamond
                    1965 Red Ext / White & Red Int. Conv. - 327/250 AC Regional Top Flight.

                    Comment

                    • Ron G.
                      Very Frequent User
                      • December 1, 1984
                      • 865

                      #11
                      During all my years of research I believe that the 68 - 72 screws for the rocker mouldings are plated black oxide. This is opinion for the door sill plates as well. Although, 99% of all hardware that is plated black is usually plated black phosphate, the reason I believe that the aforementioned are plated black oxide is that they are visibly seen and is more eye appealing. Years ago, when I was researching with assembly line procedures and having conversations with GM employees, I was informed that they did use black oxide for some of their hardware. Hope this helps. - Ron
                      "SOLID LIFTERS MATTER"

                      Comment

                      • Michael G.
                        Extremely Frequent Poster
                        • November 12, 2008
                        • 2157

                        #12
                        Originally posted by Ron Goduti (8076)
                        During all my years of research I believe that the 68 - 72 screws for the rocker mouldings are plated black oxide. This is opinion for the door sill plates as well. Although, 99% of all hardware that is plated black is usually plated black phosphate, the reason I believe that the aforementioned are plated black oxide is that they are visibly seen and is more eye appealing. Years ago, when I was researching with assembly line procedures and having conversations with GM employees, I was informed that they did use black oxide for some of their hardware. Hope this helps. - Ron
                        Ron: I don’t know what you’re referring to as “black oxide”, but the finish GM referred to as ”black oxide” was used on exterior fasteners, but ONLY on stainless steel screws, as it lent NO corrosion protection whatsoever. GM had many fastener finishes designed for exterior use on carbon steel screws, black oxide was not one that was ever used in such an application. It is possible that GM-6138M was used, which has a smooth black oxide-type coating, applied over several electroplates. Black oxide alone will NOT work in such an application.
                        Mike




                        1965 Black Ext / Silver Int. Coupe, L84 Duntov, French Lick, 2023 - Triple Diamond
                        1965 Red Ext / White & Red Int. Conv. - 327/250 AC Regional Top Flight.

                        Comment

                        • Ron G.
                          Very Frequent User
                          • December 1, 1984
                          • 865

                          #13
                          Sorry, I was referring to the 68-72 models with emphasis on the 70-72's.
                          "SOLID LIFTERS MATTER"

                          Comment

                          • Alan D.
                            Extremely Frequent Poster
                            • January 1, 2005
                            • 2038

                            #14
                            Jim, I vote for the one on the right. As far as I can remember these are on my 64 (not going to take rocker Off)
                            Believe the screw is pn 3848300 and U-Nut pn 3846854, have not found yet in any of my books. Sorry still not use to this new format: top or bottom ????

                            Comment

                            • James W.
                              Extremely Frequent Poster
                              • December 1, 1990
                              • 2655

                              #15
                              Originally posted by Alan Drake (43261)
                              Jim, I vote for the one on the right. As far as I can remember these are on my 64 (not going to take rocker Off)
                              Believe the screw is pn 3848300 and U-Nut pn 3846854, have not found yet in any of my books. Sorry still not use to this new format: top or bottom ????
                              Alan,

                              Yes, the screw and U-nut on the right are the ones I removed from the car and soaked in EvapoRust. There was evidence that my dad had them off in 1977 when he repainted the car. He had cleaned and painted the the rocker molding retainers dull silver. The screws and U-nuts were as-found when I removed the rocker moldings a few months ago to begin prepping the car for flight judging.

                              James

                              Comment

                              Working...
                              Searching...Please wait.
                              An unexpected error was returned: 'Your submission could not be processed because you have logged in since the previous page was loaded.

                              Please push the back button and reload the previous window.'
                              An unexpected error was returned: 'Your submission could not be processed because the token has expired.

                              Please push the back button and reload the previous window.'
                              An internal error has occurred and the module cannot be displayed.
                              There are no results that meet this criteria.
                              Search Result for "|||"