Automotive Fastener Transition - NCRS Discussion Boards

Automotive Fastener Transition

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  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    Automotive Fastener Transition

    It used to be that one area where the "old remained alive" was automotive fasteners. That's because even though cars changed a lot over time, the fasteners used to keep everything together didn't change very much. So, one could obtain fasteners through GM Standard Parts for very old applications that remained available in their exact original configuration (headmark excepted) many years after the car was out-of-production. Of course, as we all know, not all fasteners used in PRODUCTION were ever available in SERVICE, but many were.

    Unfortunately, all that changed with the transition to metric. For Corvettes, the transition to metric fasteners began at the end of the C3 era. The C4 era was the major transition period and by 1996, about all that remained of standard, English size fasteners were most of those used on the engine. For the C5 era and beyond, virtually every fastener on the car is metric.

    As the use of metric fasteners increased on newer vehicles, the phase-out of standard size fasteners in SERVICE inventory began. Virtually no new standard size fastener part numbers have been added by GMSPO for years and those which have been staples for decades disappeared. At the same time, metric fastener part numbers have increased dramatically.

    As I mentioned, the transition to metric fasteners has just about completely taken over in GM vehicles. The only exceptions are certain engines which are long in the tooth. That's because GM has never really changed-over fastener type for basic engine families---whatever they start with, they end with. The Chevrolet Gen I and II small blocks are an example. They were born in 1955 with standard size fasteners and they are built to this day with MOSTLY standard size fasteners. Of course, these engines have not been used in PRODUCTION for several years. They are built today for SERVICE, marine and industrial applications only.

    The only PRODUCTION engines built today which use MOSTLY standard size fasteners are the 3800 V-6 which dates back to about 1964 and the 4300 V-6 which is based on the old Gen I small block V-8. The 3800 is now used only in the Pontiac Grand Prix and the Buick LaCrosse and Lucerne. The Grand Prix goes out-of-production any day now and the 3800 engine plant is slated for closure at the end of the 2008 or 2009 model year. The 4300 is used only as the base engine in Chevrolet and GMC pick-ups and will soon be replaced by the in-line DOHC engines.

    So, it won't be too long that they're won't be a standard, English-sized fastener used anywhere on any GM vehicle. Certainly not Corvettes; they haven't used standard size fasteners in a long time. If all one works on is C5 and C6, one doesn't really need any standard size tools in one's tool box.
    In Appreciation of John Hinckley
  • Terry M.
    Beyond Control Poster
    • September 30, 1980
    • 15573

    #2
    Re: Automotive Fastener Transition

    Perhaps it is a specialized fastener, but the rear axle nut (at the outboard end of the axle) on the C6 is kind of interesting. Owners have found some take a 33mm socket, and some a 34mm. At the factory they use a 1 5/16 socket and it fits all of the nuts. So far I have been unsuccessful in getting a print for the nut so I can find out if it is really metric or English.
    Terry

    Comment

    • Terry M.
      Beyond Control Poster
      • September 30, 1980
      • 15573

      #3
      Re: Automotive Fastener Transition

      Perhaps it is a specialized fastener, but the rear axle nut (at the outboard end of the axle) on the C6 is kind of interesting. Owners have found some take a 33mm socket, and some a 34mm. At the factory they use a 1 5/16 socket and it fits all of the nuts. So far I have been unsuccessful in getting a print for the nut so I can find out if it is really metric or English.
      Terry

      Comment

      • Joe L.
        Beyond Control Poster
        • February 1, 1988
        • 43193

        #4
        Re: Automotive Fastener Transition

        Terry-----

        From what I can tell, it's an M27 thread size.
        In Appreciation of John Hinckley

        Comment

        • Joe L.
          Beyond Control Poster
          • February 1, 1988
          • 43193

          #5
          Re: Automotive Fastener Transition

          Terry-----

          From what I can tell, it's an M27 thread size.
          In Appreciation of John Hinckley

          Comment

          • Terry M.
            Beyond Control Poster
            • September 30, 1980
            • 15573

            #6
            Re: Automotive Fastener Transition

            But that does not necessarily dictate a metric hex, does it? I know if it were a standard nut it would, but then why do some owners report one size socket works and others need a larger size? I know about standard deviation in larger hex sizes, but one would think that would be minimized -- unless it would cost too much.
            Terry

            Comment

            • Terry M.
              Beyond Control Poster
              • September 30, 1980
              • 15573

              #7
              Re: Automotive Fastener Transition

              But that does not necessarily dictate a metric hex, does it? I know if it were a standard nut it would, but then why do some owners report one size socket works and others need a larger size? I know about standard deviation in larger hex sizes, but one would think that would be minimized -- unless it would cost too much.
              Terry

              Comment

              • Bryan L.
                Very Frequent User
                • June 30, 1998
                • 397

                #8
                Re: Automotive Fastener Transition

                Harley Davidson didn't cave into the "change everything to metric" crapola. My 04 Road King still had the correct good old standard American nuts and bolts. It drives me crazy to try to take off a metric bolt and have to grab 3 or 4 different sockets until you find the right one. I've resisted for many years but finally had to have a few metric tools but it still irks me. It's hard to teach an old dog something new.

                BL

                Comment

                • Bryan L.
                  Very Frequent User
                  • June 30, 1998
                  • 397

                  #9
                  Re: Automotive Fastener Transition

                  Harley Davidson didn't cave into the "change everything to metric" crapola. My 04 Road King still had the correct good old standard American nuts and bolts. It drives me crazy to try to take off a metric bolt and have to grab 3 or 4 different sockets until you find the right one. I've resisted for many years but finally had to have a few metric tools but it still irks me. It's hard to teach an old dog something new.

                  BL

                  Comment

                  • Joe L.
                    Beyond Control Poster
                    • February 1, 1988
                    • 43193

                    #10
                    Re: Automotive Fastener Transition

                    Terry------

                    Theoretically, a metric thread size would not necessarily have to include a metric size across-the-flats (i.e. wrench size). However, I have never found a single fastener that had thread size in one system and wrench size in another. It is true, though, that certain metric wrench sizes are very close to inch sizes.

                    I don't know why some folks would report that the nut had differing across-the-flats size. I would not expect that quality control on these would be that bad.
                    In Appreciation of John Hinckley

                    Comment

                    • Joe L.
                      Beyond Control Poster
                      • February 1, 1988
                      • 43193

                      #11
                      Re: Automotive Fastener Transition

                      Terry------

                      Theoretically, a metric thread size would not necessarily have to include a metric size across-the-flats (i.e. wrench size). However, I have never found a single fastener that had thread size in one system and wrench size in another. It is true, though, that certain metric wrench sizes are very close to inch sizes.

                      I don't know why some folks would report that the nut had differing across-the-flats size. I would not expect that quality control on these would be that bad.
                      In Appreciation of John Hinckley

                      Comment

                      • Wayne P.
                        Extremely Frequent Poster
                        • August 31, 1975
                        • 1025

                        #12
                        Re: Automotive Fastener Transition

                        The oil pressure sending unit on an LS1 is also standard size.

                        Comment

                        • Wayne P.
                          Extremely Frequent Poster
                          • August 31, 1975
                          • 1025

                          #13
                          Re: Automotive Fastener Transition

                          The oil pressure sending unit on an LS1 is also standard size.

                          Comment

                          • Christopher R.
                            Extremely Frequent Poster
                            • March 31, 1975
                            • 1599

                            #14
                            Re: Automotive Fastener Transition

                            I bought a Gen. 1 small block water pump at a flea market. It had been rebuilt by the time I got it. The cap screws holding the backing plate on are the usual 1/4-20x3/8". But they have 10mm heads. I still have them at home. I'm sure they are metric. I tried 9 ways from Sunday to fit a 7/16" or a 3/8" wrench on them. No go. The heads are not munged up, and I've cleaned the paint off them. They have "88" embossed in the heads. The bolts are flange head bolts. They do not have captured washers.

                            Comment

                            • Christopher R.
                              Extremely Frequent Poster
                              • March 31, 1975
                              • 1599

                              #15
                              Re: Automotive Fastener Transition

                              I bought a Gen. 1 small block water pump at a flea market. It had been rebuilt by the time I got it. The cap screws holding the backing plate on are the usual 1/4-20x3/8". But they have 10mm heads. I still have them at home. I'm sure they are metric. I tried 9 ways from Sunday to fit a 7/16" or a 3/8" wrench on them. No go. The heads are not munged up, and I've cleaned the paint off them. They have "88" embossed in the heads. The bolts are flange head bolts. They do not have captured washers.

                              Comment

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