Question for Joe,John, others- 67 Diff - NCRS Discussion Boards

Question for Joe,John, others- 67 Diff

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  • Gary R.
    Extremely Frequent Poster
    • April 1, 1989
    • 1796

    Question for Joe,John, others- 67 Diff

    I have in a 355 diff out of a 67 BB, date coded in 1966. This appears to never have been touched, still had the Hyatt bearings in it. The odd thing is the carrier (housing) is the later type used in the 69-79 run,it has the thick cast shims and is the wider version. I think I may have had a similar 66 or 67 like this a few years ago, but usually they have the narrower housing and thin 080-090 shims.

    Any reason for this? I thought it might be a '76 housing but it's not. The internals are all 60's version. Along with the bearings, the posi is the first design used from 65-68. It has the HD yokes and1310 yoke.
  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    #2
    Re: Question for Joe,John, others- 67 Diff

    Originally posted by Gary Ramadei (14833)
    I have in a 355 diff out of a 67 BB, date coded in 1966. This appears to never have been touched, still had the Hyatt bearings in it. The odd thing is the carrier (housing) is the later type used in the 69-79 run,it has the thick cast shims and is the wider version. I think I may have had a similar 66 or 67 like this a few years ago, but usually they have the narrower housing and thin 080-090 shims.

    Any reason for this? I thought it might be a '76 housing but it's not. The internals are all 60's version. Along with the bearings, the posi is the first design used from 65-68. It has the HD yokes and1310 yoke.
    Gary-----


    The PART NUMBER (not the casting number) for the carrier housing changed for the 1967 model year. It is possible, though, that early 1967's used the previous part number. In any event, part number 3917861 was used for 1967, if not from the very beginning of the year, right through the 1979 model year. I believe the feature that you described is a feature of the 3917161. So, I would expect to find that configuration for 1967-79 Corvettes excepting, possibly, some early 1967's.
    In Appreciation of John Hinckley

    Comment

    • Gary R.
      Extremely Frequent Poster
      • April 1, 1989
      • 1796

      #3
      Re: Question for Joe,John, others- 67 Diff

      Joe
      You're probably correct, I would have to go back and look up some 67 & 68 diffs I did to see if there is a break in the run. If I get some time I may just do that to see.
      Thanks Joe
      Gary

      Comment

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

        #4
        Re: Question for Joe,John, others- 67 Diff

        Originally posted by Gary Ramadei (14833)
        Joe
        You're probably correct, I would have to go back and look up some 67 & 68 diffs I did to see if there is a break in the run. If I get some time I may just do that to see.
        Thanks Joe
        Gary
        Gary------

        I actually have an NOS GM #3917161 [not for sale] that I purchased from GM MANY years ago when they were still available. It was supplied in a very heavy cardboard box with the part number stenciled on the box. When I opened the box, the carrier case was packed in "cosmoline" and inside of a bag. As I recall, there was also a muslin bag which contains shims that was packed inside. I never even took the case out since I did not want to remove the "cosmoline" and I didn't want to get it all over everything. So, the carrier case still resides in the box it was supplied in awaiting my possible future use.
        In Appreciation of John Hinckley

        Comment

        • Gary R.
          Extremely Frequent Poster
          • April 1, 1989
          • 1796

          #5
          Re: Question for Joe,John, others- 67 Diff

          Ah yes Comosline, when I was kid out of trade school my first real job was in machine service. The day I started I had to clean off cosmoline from all the new Bridgeport mills we had coming in for customers. I hate that stuff.

          Did the carrier come with any stamping on it or just a date code?

          I have a few of them here but none are NOS, hold on to it. Who knows you may want to make a 12 bolt out of it someday!!!

          Comment

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

            #6
            Re: Question for Joe,John, others- 67 Diff

            Originally posted by Gary Ramadei (14833)
            Ah yes Comosline, when I was kid out of trade school my first real job was in machine service. The day I started I had to clean off cosmoline from all the new Bridgeport mills we had coming in for customers. I hate that stuff.

            Did the carrier come with any stamping on it or just a date code?

            I have a few of them here but none are NOS, hold on to it. Who knows you may want to make a 12 bolt out of it someday!!!
            Gary------


            I'd love to know what stamping, if any, is on the case but I've just never been willing to "brave the cosmoline" to find out. Every-now-and-then I say to myself I'm going to pull that thing out of the packaging and examine it because I'm so curious. Then, I think about it some more and decide to do it "later".
            In Appreciation of John Hinckley

            Comment

            • Wayne M.
              Expired
              • March 1, 1980
              • 6414

              #7
              Re: Question for Joe,John, others- 67 Diff

              Gary, Joe -- very interesting thread. Maybe I can add some observations and questions.

              I wasn't aware of the wide/narrow case dimension difference betweent the output yoke openings. Sure enough, I examined my '65 carrier [cast date D_5_5, #3876476-N (GM part # 3822962 ?)] and it is narrower than another empty '67 carrier I have [cast D_12_7, # 3899143 (GM part # 3876475 ?)]. Just picked up a third pumpkin (early '69) with 2nd design Eaton posi case still installed, and I see it has either a cast iron or replacement steel 0.160" spacer on one side, and 4 shims on the other side. Such a thick shim/spacer stack would never fit on the earlier design carrier.

              I see in the parts history that 3822962 was replaced in service by 3876475 by 5-66. Probably production would have changed by that date, or even earlier, meaning that all '67 production, and maybe even late '66, would have had the wider case, cast # 3899143.

              Comment

              • Gary R.
                Extremely Frequent Poster
                • April 1, 1989
                • 1796

                #8
                Re: Question for Joe,John, others- 67 Diff

                Hi Wayne.
                I believe Joe is correct on the 67 change over to the housings. There is no evidence this was ever opened up in the past. I think the oil was 40 years old.

                This has the first design Eaton and it is in great shape. I blended and polished it so it will live another 40 years.

                Typically I find about 50% of the first design cracked when opened up, looking at the casting seams there are two that run parallel around the OD.

                The 2nd design casting had a staggered seam and this may have made it stronger even with the larger "tear-drop" window.

                For those that may be interested, here is what this looked like when I pulled it out.




                I washed it good to check the edges




                Here are the seams after cleaning it up good. It hasn't been this clean since 1967!



                Here it is after I blended it in. The trick is not to remove too much material.



                Comment

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