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welding onto a truck frame.....

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  • welding onto a truck frame.....

    now that i have welded my mud flap brackets to the frame, people have been posting that welding to the frame is not advised. when i got my 5th wheel hitch installed, they welded 4 brackets to the frame. am i missing something here, or shouldn't they have welded the brackets to the frame? is the frame hardened and then heat treated? if this is the case, i can see how welding would adversely affect the strength of the frame.

  • #2
    what kind of truck is it ?

    The only kind of truck frames I know of that you shouldn't weld on is big rig type trucks ... and they normally have a sticker that says "Do not weld"

    There seems to be a perpetual myth about not welding on your avg (1/2, 3/4, 1 ton) truck frame that just isn't true. if your truck is one of those then it's just mild steel, have at it.

    - jack
    Last edited by morpheus; 10-20-2003, 05:00 PM.


    • #3
      Even on small trucks never weld on the top and bottom flanges. There are some exceptions for welding lengthways in the web. Another thing to keep in mind when you are having stuff installed that most equipment dealers have a flat rate for installs and they could care less about your truck. The butchers will do anything, cut into any wire harness and it works till you get out the drive is all they care about.


      • #4
        S hit that nail right square on the head with a 10# hammer.
        Most of the sumbiches installing equipment on trucka ain't smart enough to know headlights from taillights, and don't give a **** how much damage they do to your vehicle, long as their paycheck clears.
        Those **** signs that say "our insurance doesn't allow customers inthe service area" are really there to prevent you from seeing what is being done to your vehicle, and how.
        Car & truck frames are alloys that require special welding procedures, and are NOT mild steel that can be welded without care.
        Body shops are famous for welding things improperly, after all, they don't care as long as the insurance company pays for the job and you accept it.
        I've been in too many "shops" where they work on RVs and install hitches, and most of them either have a cheap buzzbox or a small wire feeder, and hope the thing lasts when they're done puttin bird**** on. They all have a case of undercoating too, just to make it hard to see their slopjob.


        • #5
          SBerry & Franz
          Your responses make me ask the question.
          I am working on a 79 F350 4x4 that has a frame cross member that is gone(either broken or rusted,I'm not sure).Would it be ok to fab a crossmember from round tube and weld in place? or should I rivet one in from a donor truck?

          Last edited by vwguy3; 10-21-2003, 06:38 AM.


          • #6
            It makes a difference where its at. You might fab one for bolt in place. Something to look for when working on these old Ford trucks, especially if they had hard life is cracks in the top flange of the frame right behind the cab. I have found several there and if I so I use 3/32 7018 and weld from inside first right over the crack, then grind out notch from top and weld back in. Then grind all welds flush and smooth inside and out. 100% penetration leaving no excess weld.


            • #7
              the DO NOT WELD sticker on a big rig is misunderstood . i have personally lengthend and shortend dozens of truck and trailer frames without ever a problem . i have 2 tractor jobs and 1 trailer suspension of my own on the road at this moment. done properly no problems. the warning is more for electroluse trouble inside the engine. also trucks nowdays are computerized, guess what happens when this is not properly adressed.


              • #8

                Well, I just happen to work part time for a body shop. Most all late model cars use a higher tensil steel that should not be welded. You have to know what your working on and if it can or cannot be welded. One thing you have no choice on now adays is the core supports are welded in instead of being bolted in...if one is bent badly, you have no choice but to weld it.

                Frames are another story...late model stuff we will not weld on. Even to pull a frame straight, it should be done cold with no heat used (loses it's temper).

                Now older stuff is fine to weld. I just did a '77 Dodge crew cab we converted into a ram truck lengthening the frame. We went overkill how we did the lengthening, but it's stronger than stock and it's designed to take stress off the weld & attachement points.

                A great deal of the stuff I weld/work on is older stuff as we specialize in doing restorations. But we still do every day walk in crash repair work. Frame straightening/alignment stuff we send out though. The boss man had a pinch clamp come loose while doing a pull and it hit him in the head throwing him back over 10 feet. After that, he could never get the nerve to use the machine again...sold it and now farms that work out to others.
                Last edited by 10secBu; 10-21-2003, 11:17 AM.


                • #9
                  The do not weld sticker is on the there cause they dont want people welding on them for stress reasons. there are only certain allowable areas to bolt to. They dont want a bunch of willy nilly attatchments welded all over a new truck frame.


                  • #10
                    Our lates 2001 Peterbuilt was purchased as a glider kit.........We extended the frame...........2 new frame rales attached to the inside of the existing frame........Bolted in Not welded in.........We did also bolt the mud flap brackets to the frame...........If you ever look at a cement mixer truck you will notice the double frame.....

                    We haul huge tubs of scrap with this baby..............typically 30,000 to 60,000 lb tubs of boreings etc......................

                    double frames are the only way we like to extend Big Trucks....However across the back of the frames is a bracket to keep the back from tweeking........Proverbial weak link.......... I think all of ours have had bolted brackets and welded brackets installed now................

                    My .02 cents worth................Be Safe..................Rock..


                    • #11
                      Speaking of modifying truck frames...Check this place out. They do some beautiful work. This place is only about five miles away from my place. Why can't I come up with an idea like this?

                      Arbo & Thor (The Junkyard Dog)
                      The Next Loud Noise You Hear Is Me!


                      • #12
                        Thanks for the reply Mr.B
                        I may take the bed off and I will be sure to look at the spot you mentioned for cracks. I bought the truck from a farm/greenhouse and I believe all they used it for was plowing snow because it only has 69m miles and it is pretty nice shape for it's age.
                        The cross member is for the rear shock mount.


                        • #13
                          I never said truck and car frames can't be welded, and I don't think that young whippersnapper S did either.
                          What I think we are trying to convey here is that welding such items isn't a task for beginners, just as installing trailer hitches isn't.
                          If frame welding was the most economical and best way to construct a truck frame, manufacturers would be welding them, rather than going to the expense of punching and riveting frames together. There's a lot more flexation going on in a truck frame than most people realize.
                          Re: the truck with 69 miles on it that was only used for snow plowing, a complete frame inspection is the first thing the truck needs. As far as replacing the cross member, I'd bolt a new one in with at least grade 5 bolts.