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Aussie RHD 1975 C20 2WD Resto mod

Discussion in '2wd Pick-Ups C/R 20 2500 C/R 30 3500' started by pduffyd, Nov 11, 2019.

  1. pduffyd

    pduffyd Full Access Member

    Posts:
    94
    Likes Received:
    106
    Joined:
    Sep 27, 2019
    Location:
    Melbourne, Australia
    First Name:
    Paul
    Truck Year:
    1975
    Truck Model:
    C20
    Engine Size:
    454
    Right next strip it down and replace the folks and small parts.

    These are the new forks to go in, and the small parts kit.

    20201005_105540.jpg

    SM465.jpg

    Looking at the 3 shafts that hold the forks in place you can see that there are 3 springs and 3 balls (toward the end caps), up the front there are 4 balls and a small alignment shaft (17.23308) going through the 3-4 folk shaft.
    So this is how I stripped it down.
    I first took a photo of how it looks before I started this process. You can look at the above photo!
    Select neutral, just use a big flat blade screw driver to move the shafts between their ends and the case.
    With a pin punch drive out the three roll pins. Also punch out the three end caps (20.0620) from inside the case.
    Using the screw driver push out the 1-2 shaft, have a magnetic tool handy to retrieve the 2 balls in the front of the cover between the shafts as this shaft moves out of its support. Remove the fork, draw out the shaft and retrieve the ball and spring in the rear support, this is the shift detent ball and spring.

    20201005_114421.jpg

    Same as the 1-2 shaft.
    Using the screw driver push out the 3-4 shaft, have a magnetic tool handy to retrieve the 2 balls in the front of the cover between the shafts and the little shaft (Keep this part) in the front of the 3-4 shaft that spaces the 4 balls. Remove the fork, draw out the shaft and retrieve the ball and spring in the rear support, this is the shift detent ball and spring.

    Last, do this for the reverse shaft.
     
  2. pduffyd

    pduffyd Full Access Member

    Posts:
    94
    Likes Received:
    106
    Joined:
    Sep 27, 2019
    Location:
    Melbourne, Australia
    First Name:
    Paul
    Truck Year:
    1975
    Truck Model:
    C20
    Engine Size:
    454
    OK so clean out the cover, check all the parts, shafts, little shaft, and make sure that the detent spring holes are clean and have no old spring bits in them.

    So re assembly is the reverse, with new parts of course.
    The only real fiddly bit is replacing the spring on the reverse gear fork lock out plunger thingy.

    One tip start the new roll pins into the forks on the bench, its a lot easier.

    20201005_115404.jpg

    20201005_115411.jpg

    As I put it all back together I used wheel bearing grease on the springs so they had some lube, and it helped to hold the balls it place.
    The trickiest part is compressing the ball on top of the spring while starting to install the fork shaft, had a couple of "where the hell did that go!" moments, lol.
    Dont forget the little shaft to be reinstalled in the 3-4 fork shaft, and the 4 balls up front. These lock the other two shafts from moving when one shaft is moved to engage a gear.

    So, once its all back together use your big screw driver on the ends of each fork shaft in turn to move between the three detents, only two on reverse.
    Bring them all to neutral, and only half engage reverse. Now the cover is ready to reinstall on the tranny.

    In the tranny make sure that gear select hubs are in neutral, and the reverse idler gear front edge of the teeth are just inline with the rear edge of the reverse gear on the main shaft.

    Now before I put the top cover back on I cheated and filled the tranny with oil.
    Of course I made sure the fill bung and drain bung were tight before I did this.It did enable me to fill to the right level with no mess, and I was able to ensure all the gears, synchros and bearing got a good coat of oil before the top went on

    This should allow the forks to all line up in their respective shifter hub slots.
    Be careful not to damage the coating on the forks!

    20201003_231959.jpg 20201013_115028.jpg

    Ready to be fitted!!
     
    Last edited: Oct 27, 2020

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