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Frame Building soon, help needed please.

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  • Frame Building soon, help needed please.

    Hi guys, hopefully getting into my frame mockup soon. I have a 29 Plymouth 4 door, 12V Cummins, Auto. Here are my wants...

    Thinking of using 2x6 for frame.
    I want to keep it a 4 seater.
    I would like to run airbags.
    The front end I am still up in the air, I really want to use a front axle from a 03 Ram, remove the pumpkin.
    I'd like to run running boards, so the frame would hang below the floor a few inches for the running board tubing would tie into that. So 3" channel into the body, 3" below.

    What is a good ride height for something this long? It will be about the length of the D ROD
    I planned on running the rear kickup the same angle as the rear seat, good idea?
    How short can you go on the link arms for the rear end? I need as much interior room as possible which will push that rear kickup back, but that shortens the link arms.
    I planned on running the fuel tank on top of the frame (inside the frame?) at the back.
    What height should the front of the frame be compared to the front axle? I think mine will kickup like the picture.

    Any other insight would be GREATLY APPRIECIATED!!!


  • #2
    Lowbudget50 is doing a build and using the front axle from a 2wd 550 ford... straight tube axle. Its pretty cool.
    look close at 2500/3500 trucks that are 2wd.
    The rear links can be pretty short, mine is all bagged with 4 link.
    put the fuel tank in the frame behind rear axle.
    My build thread:


    • #3
      Thank you for the input. I want to mock up a frame with some 2x6 lumber just to get a rough idea on the rear.


      • #4
        It's a good idea, wood is much cheaper and easier to work with, then you can figure very close to exactly how much you need for the build.
        My build thread:


        • #5
          So I never took into account the height of the rocker. So I was thinking of maybe using 2x5 for the frame. That way maybe I could get away from channeling the body and just running the floor flat across like it is now. A couple of inches behind the rocker would leave a few inches under the rocker which would leave enough to weld my running and boards on to. Thoughts? Would 2x5 be enough for a cummins? Stock now, but want it strong enough for mods later. If so, what wall thickness?


          • #6
            I would think 2x5x3/16 would be plenty.
            remember theres a fine line to building a frame with enough strength but also having enough flex. Too rigid and you get cracks.
            My build thread:


            • #7
              Just wondering if I'm on the right now track. I would really like to know if I can push the back upright back more.


              • #8
                Depending on what your using for rear suspension, your frame can be cut and made level with the ground, above the rear axle, for as far towards the rear as you want to run it. The frame will need to be high enough to clear the rear axle as it moves up and down with the suspension travel. Normally, at ride height, with the car fully loaded, you need about 3" to 4" of clearance between the frame and the axle. If you intend to lay the frame on the ground, you will probably need more clearance between the frame and the axle.

                If your going to make the car as long as its laid out in the 2nd picture, you may want to raise the front of the frame a bit, unless you will be able to adjust it higher with bags or something when you drive it. If its set as low under the firewall as it looks, its going to bottom out going in and out of a lot of driveways. Nothing sucks more then getting a car stuck on the frame when you lift the front or rear wheels off the ground going into a McDonald's parking lot. Long wheel base cars need more ground clearance at the center of the car.

                It looks like you have decided what your using for axles, now you need to figure out what the front and rear suspension will be, and if that suspension will be adjustable or not. If its adjustable (you can move it up or down as you drive), then you need to decide if you want the car to be able to sit on the frame when your parked. If its not adjustable or not, you will need to decide how far off the ground you want the frame to ride when your driving the car.
                Then you will need to figure out where your motor and transmission will sit. I see it looks like you have your block positioned in the 2nd picture. If your running an auto trans, that location would probably be OK, but if your running a standard shift trans, Clutch and shift linkage might be an issue with the motor sitting that far forward of the body. If you have that figured out, keep going, in not figured out yet, I might suggest you move the body forward so the trans is in a more normal position. For a 1st build, I like to keep things as simple as possible, there will be enough other stuff to keep you busy figuring stuff out.

                Once you have determined how far off the ground the car needs to be when your driving it, and you know what your going to use for front and rear suspension, you can begin to lay out your frame. Start with the long boards on each side that will be between the front tires and the rear tires (the frame rails that are under most of the body). Typically, you want those boards (frame rails) to be a close to level to the ground as possible, and they need to be raised off the ground to your determined ride height. A good rule of thumb is you want those boards to start at the rear edge of the front tires, and go all the way back to the front edge of the rear tires. (they are wood, you can cut them shorter later if you need to, but its pretty hard to make them longer).
                Next, you want to set the boards that go to the front of the car. Those should start at the rear of the front tires (yes, the same edge as the under body boards ended) and the need to go forward as far as your front bumper or grille. Its usually best if these boards are as level with the ground as possible (makes the build easier). The height of these boards off the ground will depend on how much suspension travel you have. Your front suspension will be attaching to these boards. Generally you need 3" of clearance between the frame and the suspension for suspension travel, then if the 1st sets of boards will be dropping to the ground, you also need to add the measurement of the ride height to the 3" of travel. You need to figure out a way to keep those 2 boards (one on each side) at the proper height off the ground. Once that is done, you can cut 2 pieces of board to fill between the height of the under body boards and the two board you just positioned above the front suspension and attach all that together, wood screws work great.
                Next you do the same thing at the rear. Cut two boards long enough to reach from the front of the rear tires, and go to your rear bumper, or where ever you want your rear frame to end. Again, those two boards should be level with the ground, and again be 3" for suspension travel, and if your laying frame, add the ride height measurement, position those boards at the proper height, and cut 2 more boards to fill the gap between the height of the rear frame boards and the underbody boards and screw it all together. What you should end up with are both your side rails, two matching sets of boards that will be above the front suspension, drop to under the body, then lift up and go above the rear axle.
                What's left are cross members. You will probably need 5 cross members. One at the rear end of the frame. One slightly forward of the rear axle, one at the rear end of your transmission, one under the front of the motor, and maybe one at the front of the frame. Generally, your pretty safe putting the side frame rails at about 32" - 34" wide. You will need to figure out where those cross members will need to be placed, and screw them into place. You can use the cross members to mount you're front and rear suspension and your motor & trans mounts. You can add more if you feel the need. Adjust things as they need to be for your car. Gene


                • #9
                  Thanks a lot Gene, the 2nd pic is kind of misleading as the ground isn't level. I know the frame will need to be kicked up as it comes out of the body. Plan is for a level frame, I'm not sure if I care if it lays frame, but I do know I don't want to constantly air up the bags every driveway, but low enough to be badass lol.


                  • #10
                    Experience tells me anything less than 4" to 5" of ground clearance to the lowest point, takes a lot of the fun away from driving them. Gene