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  • Welding a vehicle frame

    Can anyone offer me some tips on welding a vehicle frame together? What I would like to do is cut a vehicle frame in half(because the rear frame is bent) and weld a good rear half back on to it. The truck frame would need to be cut in the center, so there would be a lot of stress in this area. Please be aware this frame is a box type frame.

    My plan is to make a top to bottom vertical cut and then weld it back together like a butt joint. What could I do to make this area as strong as it needs to be.

    Thanks

  • #2
    It would need more reinforcement than just butt welding it back together.

    You will need some sort of fish plates welded over the butt joints, and perhaps more reincorcement.

    You also might consider making a step cut in each of the frames, and having them mate together.

    Finally, this might be a bad idea altogether, and it might be better to just find a straight frame, if possible.

    -James

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    • #3
      No straight cuts on frames. Sides, and top/bottom flanges should be cut on 45 degree angles to disperse stress loads and to allow for greatest amount of weld surface area.

      To re-inforce, either load frame inside with tubing that fits inside of current frame, or weld on "fish plating" or load dispersing panels on the outside as mentioned.

      Maybe do some checking around to see if someone in your area has done this sort of thing before and is willing to give you some tips and hands-on demonstration.

      I have no idea of your skill level, and intend no insult, but when doing this kind of work, you don't really have any room for errors.

      Opinions vary, this is how I'd do it.

      Best of Luck.
      Later,
      Jason

      Professional Spark Generator by Trade.

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      • #4
        Don't hold me to the wall here but I read somewhere not to do vertical welds on a frame especially in an area of high stress. If you did weld the new back half
        of the frame on you would need reinforcement plates. Again, when welding the side plates, weld only the horzintal top and bottom, not the vertical left and right ends.............per the article I read. The heat generated at the vertical welds changes the metal some and invites a new place to break.
        Be sure to get the advice of a pro.
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        • #5
          Ditto

          Originally posted by monte55 View Post
          Don't hold me to the wall here but I read somewhere not to do vertical welds on a frame especially in an area of high stress.
          Vertical welds will ALWAYS break because the stress is pulling across the the width of the bead instead of dispersing along the length.

          Good luck.
          Triggerman

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          • #6
            Originally posted by triggerman View Post
            Vertical welds will ALWAYS break because the stress is pulling across the the width of the bead instead of dispersing along the length.
            Interesting. Would seem odd (to this newbie type) to leave ends of fish plate bare. Could you put a couple of plug welds near each edge, iinstead?

            And, someone above had suggested a step cut. Are you saying the verticals there can't be welded?

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            • #7
              Atrorm

              No vertical welds. They ALWAYS crack.
              Triggerman

              Ammonia refrigeration tech
              Trailblazer 302 (yes, it's new)
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              Victor O/A, DeWalt, North mask


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              • #8
                Originally posted by triggerman View Post
                Vertical welds will ALWAYS break because the stress is pulling across the the width of the bead instead of dispersing along the length.

                Good luck.


                Ahhh yes, tension vs. shear

                For Aircraft we use a 30 degree angle for all splices, along with a doubler inside, or a sleeve outside of the tube, also with the ends cut at 30 degrees if an external sleeve. Is this for on or off road use? Depending on the State, the local DOT may have regulations on this type of repair.

                -Aaron
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                • #9
                  Before you even attempt this, you may also want to check with an inspection station. This may not even be legal and the liability could also be a problem if you or somebody else would be involved in an accident.

                  Another tip, when a vehicle is made, the VIN number is stamped at least 10 different places on a vehicle so it or its parts can be traced when they are stolen. You may even need to apply for a reconstructed title.
                  Ken

                  What else is there besides welding and riding. Besides that

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                  • #10
                    welded frame

                    i did a mack truck one time..the owner said he went to mac truck and asked them ..this is what he had me do...cut on 30 degree angle..weld all around and then grind the outside flush..he had ordered another C channel from Mack to fit over the original frame...stuck by `18 inches each side...six bolts on each side...no welding on this piece allowed..
                    the top flange of the channel was allowed to be notched for any obstructions caused by the original frame but not the bottom flange...anything here had to be removed and put back on the new bottom flange

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                    • #11
                      sleeve it

                      Wirefeeder, assuming you are sectioning this frame in a more or less straight and flat area.....I would cut it at approximately 30 deg and install a sleeve at least the same thickness material . The length would be twice the height of the frame rail involved as long as you have clearance to fit . Rosette weld/spot weld minimum four spots per side of each rail plus leave about 1/8 gap between rails with a bevel on rails to make full penetration with sleeve when fully welded together. This method has been done in our shop successfully. Also if its a late model vehicle you might have to check with your DOT about VIN numbers etc. If its an older vehicle Weld On
                      Hope this helps Jim uhohjim1@aol.com
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                      • #12
                        [QUOTE=billie-t;23739]i did a mack truck one time..the owner said he went to mac truck and asked them ..this is what he had me do...cut on 30 degree angle..weld all around and then grind the outside flush..he had ordered another C channel from Mack to fit over the original frame...stuck by `18 inches each side...six bolts on each side...no welding on this piece allowed..
                        the top flange of the channel was allowed to be notched for any obstructions caused by the original frame but not the bottom flange...anything here had to be removed and put back on the new bottom flange[/Q




                        billie-t, you are right on target with your reply.
                        This is the method that we have followed as instructed by several vehicle manufacturers. The bolts should also be a minimum of 5/8" diameter with a shank where it goes through the frame and grade 8 also. Dave
                        If necessity is the Mother of Invention, I must be the Father of Desperation!

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                        • #13
                          [QUOTE=dabar39;24176]
                          Originally posted by billie-t View Post
                          i did a mack truck one time..the owner said he went to mac truck and asked them ..this is what he had me do...cut on 30 degree angle..weld all around and then grind the outside flush..he had ordered another C channel from Mack to fit over the original frame...stuck by `18 inches each side...six bolts on each side...no welding on this piece allowed..
                          the top flange of the channel was allowed to be notched for any obstructions caused by the original frame but not the bottom flange...anything here had to be removed and put back on the new bottom flange[/Q




                          billie-t, you are right on target with your reply.
                          This is the method that we have followed as instructed by several vehicle manufacturers. The bolts should also be a minimum of 5/8" diameter with a shank where it goes through the frame and grade 8 also. Dave
                          The only problem with that repair is it cant be done on a box frame..its a C channel frame repair.......but it is the way to go on a semi or other heavy duty truck
                          Jim
                          Welding in Crete
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                          Hypertherm Powermax 30
                          Some really cool hammers BIG and small

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