12 Bolt Rear Swap

Discussion in '1947-1954' started by RidesWithYah, Oct 3, 2022.

  1. RidesWithYah

    RidesWithYah Member

    Joined:
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    Location:
    Lexington KY
    Need some advice, as I know nothing about rear ends.
    A couple of years back this was advertised for sale near me.
    The guy said it was working fine, came on his truck when he bought it, and he did a complete build (whole new drivetrain) and went a different direction.
    It appears to be a 12 Bolt Truck rear, 62" overall.
    Passenger side tube is stamped H A 05 01 W.
    Leaf springs and mounts have been added, and match my '51 exactly.
    Was going to just bolt it in, but spring eyes have been wallered out,
    so unless there's a trick I don't know need to be replaced.
    I have a line on Dorman 22-195 for $120, any reason not to use those?

    Casting number on the carrier is 3866118.
    Gear is marked 3817778 11:41 GM 6-67 1-2.
    So I assume I'm looking at a 1967, 3.73:1, Open rear.
    I see no rust, chips, or weird markings on the teeth; am I missing something?
    A little bit of rust on the carrier, is that a concern?
    Or just replace the gasket, fill with gear oil and run it?

    Obviously needs brakes, I'm thinking this is the common 11x2 setup and pretty straightforward.

    Thanks for any insights.
    IMG_2766.jpg IMG_2767.jpg IMG_2772.jpg IMG_2773.jpg IMG_2759.jpg IMG_2760.jpg
     
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  2. coilover

    coilover Member

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    Stick it in and run it. New bushings will keep the spring eye bolt centered for a long time. 3.73 is perfect if you ever go with an OD transmission but will let you run 60mph without strain.
     
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  3. RidesWithYah

    RidesWithYah Member

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    Lexington KY
    Thanks - appreciate the vote of confidence.
    And yes, I am planning an OD.

    Even with new bushings, those spring eyes were worn enough to have plenty of slop.
    I looked for new 55.1 springs (centered pins) and couldn't find any, so ordered the Dorman 22-195s.
    Some talk in the forums about flipping the springs front-to-back to center the rear - I had even repeated the tale in at least one thread.
    Looks like that would move the rear on the order of 3.5";
    more than the consensus 1.5" or so it takes to center.
    I think this backs up the report in one post that reversing them was too much...
    So I ordered one of the shim kits with offset pins.
    Just need to drill my tie plates to match.

    IMG_2898.jpg
     
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  4. vwnate1

    vwnate1 Member

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    Well ;

    You're supposed to measure the center bolt from the middle of the hole but it looks to me like you're going to be fine .

    Don't forget to drop a rare earth disc magnet ($6 package of 6 at Harbor Fright) in the bottom of the banjo housing .

    I look at the wear on the crown wheel and will be amazed if it's dead silent but it should work just fine .

    DO NOT fail to add the magnet because RUST NEVER SLEEPS and the microscopic rust particles will ruin the bearings ere long .

     
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  5. vwnate1

    vwnate1 Member

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    FWIW ;

    If you want a better ride it's a time consuming but very worthwhile job to disassemble the entire spring pack and fit Teflon leaves between each spring leaf ~ this reduces friction and allows the spring to react faster improving ride and handling as well as lengthening spring life.....

    You appear to have a good grasp of both what you want to accomplish as well as what to do .
     
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  6. RidesWithYah

    RidesWithYah Member

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    Location:
    Lexington KY
    First time trying POR-15.
    Laid down smooth even with a brush,
    and I'm no painter.
    Hoping to get both front and rear axles hung on the frame next weekend.
    IMG_3749.jpg
     
  7. vwnate1

    vwnate1 Member

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    Looking good ! .

    Many years ago i used POR15 to paint the outside on a British car's gas tank, it too went on smoothly ad dried well .

    I no longer remember the thinner but some used to thin POR15 and use in their spray guns .

    It's critical to clean the gun the instant you're done painting as once that crap dries it's there forever .
     
  8. RidesWithYah

    RidesWithYah Member

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    Location:
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    When swapping to an open rear, what are y'all doing for rear shock mounts? The leaf spring perches on my axle are 2.5" wide, even though the springs are only 1.75". That puts the u-bolts too far apart to use the stock ties/shock mounts, and the tie plates I have found with this spacing don't have shock mounts included. (Also, I snapped the studs off the stock shock mounts, so reworking them isn't an option.)

    EDIT - found these made for 2.5" springs and 3" axle tubes. Holes are drilled for 1/2" U-bolts so I might need to open them a bit (and drill a new clearance hold for the spring center pin), but they might work.

    Leaf Spring Shock Mount Plate, Rear Driver Side, 1967-1973 Jeepster Commando and Jeep Commando | Jeepster Man Inc

    Leaf Spring Shock Mount Plate, Rear Passenger Side, 1967-1973, Jeepster Commando and Jeep Commando | Jeepster Man Inc

    Or I might just buy a new pair of stock mounts and put them under the generic tie plates I already have.
     
    Last edited: Dec 16, 2022

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