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Thread: Hairba11's mk48/17

  1. #1
    Join Date
    Jun 2017
    Posts
    61

    Default Hairba11's mk48/17 (4x4 tractor + 4x4 trailer = 8x8)

    So I picked up a HEMTT body set a few months ago and started collecting parts for this build.
    The Mk48 differs from the HEMTT in a couple of ways. Although it looks almost the same, it's a 4x4tractor/4x4 trailer arrangement instead of an 8x8.
    The Mk48 tractor can be attached to a handful of different trailers. The 14 is a flatbed, the 15 is a wrecker, the 17 is a cargo, etc.

    This is the tractor without a trailer. I've driven one once, about 200 feet from one trailer to the next, and it's one of the most unique vehicles I've driven. Like being able to steer a roller coaster. I think my seat moved over a foot vertically between gas and brake.
    Because the tractor is self contained the fuel tanks are on top of the fenders, the spare is on top of the hitch, and I have a lot of work ahead of me.


    Suspension should be pretty easy. Walking beam with leafs and multi link setup. When the tractor is maneuvered without a trailer, little blocks fold down between the frame and rear axle to lock out the suspension.

    The pivot at the back of the tractor will be a challenge.

    The rest of the hitch is a fairly simple box. The actual connection to the trailer is at the front of the trailer frame. Sixteen 3/4" bolts hold the hitch plate to the trailer. Add in a couple of electrical a couple of air, and a couple of hydraulic quick connects, and eight 3/8 bolts for the drive shaft flange and a couple of hours later you have a new trailer.

    And don't forget about the big hydraulic rams. The trailer hitch has forced articulation tied in with the steering wheel.


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  2. #2
    Join Date
    Jul 2010
    Location
    It no longer exists.
    Posts
    9,549

    Default

    Well that's going to be a fun build. Eagerly awaiting more!
    SBG OWNER YOUTUBE AXIAL AMBASSADOR GCM TEAM DRIVER VANQUISH KNIGHT CUSTOMS TEAM

  3. #3
    Join Date
    Jun 2017
    Posts
    61

    Default

    So I know the 1:1 has a straight frame with suspension trunnions and I knew my ability to knock out true, straight, level trunnions conflicts with my patience. So I cheated. I found aluminum shock towers for the rear of the scx10/generic scale chassis for about $15/pair on eBay. Lots of adjustability with a bunch of threaded holes.
    Add a set of leaf springs and mount it to the chassis upside down.

    It's really hard to find military looking wheels. The militants would be perfect, but 2.2 is a little large, and the price is steep for 8 wheels.
    I ended up finding gmade 1.9 steel wheels.
    These things were awesome to put together. They included longer screws to pull the wheels together. They are finished with hex head bolts and include a tiny socket which fits on the end of the 2.5mm wrench

    For tires it was tough finding the height and width needed in 1.9, so I used some 2.2 Rock Lox and cut-n-shut them.




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  4. #4
    Join Date
    Jun 2017
    Posts
    61

    Default

    So making so shorty upper links, and hooking the axles together with long lower links and locating the lower with the leaf pack gives me a decent walking beam.







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  5. #5
    Join Date
    Jun 2017
    Posts
    61

    Default


    So here it is.
    Now to work on the hitch


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  6. #6
    Join Date
    Jun 2017
    Posts
    61

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    So I started mocking up some metal tabs for hinge points


    Then welded up a hitch shaped box.


    The holes on the hitch side are 13/64, the holes on the tractor side are 11/64 tapped 10-32 so I don't have hinge nuts interference with the drive shafts


    Mocked in place


    And trailer bolted to hitch like the 1:1, with my custom long driveshaft


    There it is. 9" wide 10"tall, 39.5" long. I was worried about making my hitch too long. It was too short. The actual length of a mk48/17 would be 41" in this roughly 1:11 scale. The masking tape roll is almost spare tire size


    The front axle steers and the trailer articulates. Should be a decent trail rig.


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  7. #7
    Join Date
    Jun 2016
    Posts
    107

    Default

    That was.... really fast. Looks really good so far, can't wait to see with paint!

  8. #8
    Join Date
    Jun 2017
    Posts
    61

    Default

    The body work still needs to be done. The everything between the cab an hitch gets reworked.

    This morning I got the motor/trans and articulation servos mounted.




    Links and Tamiya's shock bodies make decent fake rams



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  9. #9
    Join Date
    Jun 2017
    Posts
    61

    Default

    So this morning I brought a radio to the shop, got my articu servos set up and made link mounts on the hitch. I also brought a speed control along and got it moving around a little




    Flexing it out on the forklift!


    And here's the 1:1 my friend has.
    As pictured from the crane hook.
    I may have been ratchet strapped to a desk chair for this.




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  10. #10
    Join Date
    Nov 2013
    Location
    Charlotte, NC
    Posts
    1,409

    Default Hairba11's mk48/17

    Wow, this build is seriously cool. I'm not familiar with these trucks, but man it's got some interesting features, and you're doing a great job incorporating them into your build.

    Very impressed. Can't wait to see this one come to life.

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