1957 Mark 30 lower unit setup

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  • October 27, 2018 at 6:26 pm #11694
    chipster303
    Participant

      US Member

      I am putting together a spare lower unit for my 1957 Mark 30 outboard. I am going crazy trying to assemble it. I have the forward gear and pinion shimmed for proper gear mesh. When I put the reverse gear assembly in, I feel binding between the reverse gear and pinion. Where/how do you shim the reverse gear to move it away from the pinion gear? There are currently no shims in the reverse gear assembly. Is it possible that the body of the lower unit was machined too deep? There should be a way to shim the gear away to get the proper clearance. Any words of advice would be appreciated.
      Thank you!

      October 27, 2018 at 8:35 pm #85069
      frankr
      Participant

        US Member

        Parts list shows shims. That’s all I know..

        October 27, 2018 at 10:26 pm #85074
        chipster303
        Participant

          US Member

          Thanks, Frank.
          I have this parts list. I have shims (part number 15-24592) but don’t think they will solve my problem. I do not have shims (part number 15-20822). They are not illustrated and I wonder where they go and if they will resolve my issue. Currently, there is only about .004 gap between the reverse gear and the ball bearing. Not sure if I can pick up any gear clearance by reducing this gap somehow.
          I have no shims (15-20788) behind the forward gear, and do not need any there.
          Thank you for your reply. I hope someone can shed light on this issue!

          October 27, 2018 at 11:49 pm #85080
          dave-bernard
          Participant

            US Member

            reverse shims go in before the reverse gear and carrier. 1 914 310 7086

            October 28, 2018 at 1:38 am #85086
            chipster303
            Participant

              US Member

              Thank you for the information, Dave. This is the only thing that makes sense to me. Although they are not illustrated on the parts drawing, they are on the parts list. It appears the correct shims are part number 15-20822. Now all I Need to do is find some.

              October 28, 2018 at 9:06 am #85089
              billw
              Participant

                US Member - 2 Years

                It’s been quite awhile since I had one apart but I don’t remember any shims between the ball bearing and reverse gear. This would be the 15-20822 you’re talking about. Even if you bought some, shimming between the ball bearing and reverse gear would only make your problem worse, moving the reverse gear CLOSER to the pinion gear. You want to be moving the reverse gear backward and away from the pinion gear. This would be accomplished by the 15-24592 shims, reference number 17, in the drawing. The general rule is that when you have no idea what amount of shims you will need, start with a total of 0.015", then start checking the clearances and making any adjustments as needed.

                Long live American manufacturing!

                October 28, 2018 at 5:57 pm #85112
                chipster303
                Participant

                  US Member

                  After noodling this thing out for a long while, and talking with Dave, it appears the 15-20822 shims between the reverse gear ball bearing adapter ring and the gear housing will move the reverse gear away from the pinion gear. Using the 15-24592 shims between the reverse gear bearing and the sealing ring assembly will move the reverse gear toward the pinion gear.

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