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4X4 selector problems / questions!

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  • #31
    Originally posted by loose gravel View Post
    Mark, what moves the 4x selector shaft? That little double slotted connector? The manual is poor in describing how that fits.
    Yes. See pic. Viewed from bottom looking up and aft. Yellow shaft controlled by yellow knob. Red shaft controlled by red lever. Green swivel is the double slotted connector you refer to. The end slots of the swivel mesh with posts on the red and the blue shafts. The center is mounted to the yellow shaft by another post about which it spins.

    PIC 1--2WD. Pin engaged in yellow shaft. Red shaft fully forward (high gear ratio) Purple 4WD dog fork slides freely along blue shaft, but is held in disengaged (2WD) position by equilibrium of spring force on either side of slider. Note angle of green swivel mechanism:

    PIC 2--4WD HIGH. Pin is disengaged from yellow shaft. Spring around fixed red shaft forces yellow shaft forward. Green swivel pivots about the post on the fixed red shaft as the yellow shaft travels forward. This causes the other end of the slotted swivel to push the blue shaft forward. Forward movement of blue shaft upsets equilibrium of springs on either side of the purple 4WD slider, decreasing the front spring bias, sending the slider/fork forward, engaging the 4WD dog, which marries the rear drive output shaft to the front drive output shaft. Note angle of green swivel mechanism:

    PIC 3--4WD LOW. Red shaft moved to full aft (low gear ratio) position with the red lever. Green swivel pivots about the post on the stationary blue shaft. Yellow shaft moves aft with the red shaft until the hole in the yellow shaft aligns with the spring loaded pin of the yellow knob, allowing the pin to drop into the hole in the shaft, thereby fixing the position of the yellow shaft once again. Note the angle of the green swivel mechanism:

    When the red lever is pushed all the way forward from here, the green swivel pivots about its center on its post on the fixed yellow shaft, sending the blue shaft rearward and changing the bias of the springs on either side of the purple 4WD fork slider so that it moves to the rear, thereby disengaging the 4WD dog and divorcing the front drive output shaft from the rear drive output shaft.

    This is my understanding of how this ingenious system works. Might be wrong about it though, but that’s how I believe it works.
    Attached Files
    Last edited by SafeAirOne; 01-14-2022, 11:47 PM.

    1973 SIII 109 regular w/2.5NA Diesel


    • #32
      Here's another example to help explain what's going on in the transfer case.

      Foreman and Wilms video helped me to understand what magic is going on inside the box!!


      • #33
        Originally posted by conrad1468 View Post

        Foreman and Wilms video helped me to understand what magic is going on inside the box!!
        Whew! Awesome video—a great resource! The graphic at the 5:35 mark validates my theory that that rusted up shaft on Nick’s transfer case is the cause of his woes.
        Last edited by SafeAirOne; 01-15-2022, 12:05 AM.

        1973 SIII 109 regular w/2.5NA Diesel


        • #34
          Conrad, Thanks for that, great find! I would love to see the full graphic video he uses.

          Also gives evidence that the "Use it or Lose it" theory is correct.
          1960 109 w/ 200TDI
          rebuild blog;

          You don't see faith healers working in hospitals for the same reason you don't see psychics winning the lottery.


          • #35
            A couple of vids showing inside transfer case. Not sure what I am looking at but maybe interesting to someone more knowledgeable!
            I think I will button it all back up as I don't need 4wd yet - and get back to it in the future. I think I will end up removing the transfer case later as I think something is not functioning properly inside. Thanks for all the help.


            • #36
              Terrific video showing the guts of the transmission including the 4WD selector shaft in question. 6:45 and 9:45 are the most relevant to this topic.
              Last edited by DouginMaine; 03-16-2022, 09:08 PM. Reason: Wanted to give specific times for this topic.


              • #37
                That’s a great video and very helpful. Basically my 4 wheel drive selector shaft is rusty and stuck in the aluminium housing. I am planning to get back to it an hopefully with penetrating oil and heat I can get it moving!