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Thread: Welding on a truck frame

  1. #1
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    Welding on a truck frame

    Making a permanent mount sander for a dump truck . I know there is a decal on the frame that says do not weld on frame but why ? When you mount a dump body you have to weld the hinge to the chassis ! You can weld a car frame ! Every race car chassis in the world is welded together so why do they say not to weld on a truck frame ? Thanks Bill !

  2. #2
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    Re: Welding on a truck frame

    those stickers have been around for awhile. various answers. High tensil steel used in the frame. etc etc. race car chassis use steel designed to be welded.

    anyhoo,

    Not being rude but you can search "Do Not Weld on Truck frame" and the ol' inter webs will deliver quite a few results.

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    Re: Welding on a truck frame

    I'm an electrician. 100% of what I can legally use must be "listed", "approved", or "identified" for a purpose. This means it must be approved by a testing laboratory for a specific purpose.

    Pretty similar stuff with truck frames. It was designed & built under specifications. When you weld to it there is great potential that your action might weaken it. I have a former fire truck, there is all manner of stuff welded to this frame. I assume the upfitter making a bare cab & chassis into a fire truck has some credentials to tamper with the frame, and an insurance policy to cover if there is a failure.

    Mostly it's about frames being a safety item, and somebody taking responsibility for safety if altered. Wouldn't want an amateur trying out a new welder on a frame. Mostly truck frames are made of high tensile steel with correct techniques & preheat, then they are "normalized" (heated to a temperature where welding stresses are relieved). Mrs. B's oven isn't big enough, or hot enough.

    If you aren't so equipped you should bolt stuff to your truck frame, ideally using existing holes.
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    Re: Welding on a truck frame

    It's mostly because welding/heating 100-120,000 lb tensile steel tends to remove the temper. Dump hinges are fine due to the fact they aren't loading the center of the frame rail, as a matter of fact a bit of annealing at the hinge weld zone is a good thing to prevent cracking. Otherwise I absolutely avoid welding anything to a frame rail... Period.
    Now, shortening or stretching a frame does require welding the full rail, but I won't do either without a tight fitting liner channel bolted in with 5/8" flange head bolts and plenty of them.

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    Re: Welding on a truck frame

    Like 12V71 said: The steel in most frames are heat treatment.
    I seen a few truck frames in scrape welded need I say more.

    Dave

    Quote Originally Posted by masracingtd1167 View Post
    Making a permanent mount sander for a dump truck . I know there is a decal on the frame that says do not weld on frame but why ? When you mount a dump body you have to weld the hinge to the chassis ! You can weld a car frame ! Every race car chassis in the world is welded together so why do they say not to weld on a truck frame ? Thanks Bill !

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    Re: Welding on a truck frame

    Quote Originally Posted by 12V71 View Post
    It's mostly because welding/heating 100-120,000 lb tensile steel tends to remove the temper. Dump hinges are fine due to the fact they aren't loading the center of the frame rail, as a matter of fact a bit of annealing at the hinge weld zone is a good thing to prevent cracking. Otherwise I absolutely avoid welding anything to a frame rail... Period.
    Now, shortening or stretching a frame does require welding the full rail, but I won't do either without a tight fitting liner channel bolted in with 5/8" flange head bolts and plenty of them.
    Quote Originally Posted by smithdoor View Post
    Like 12V71 said: The steel in most frames are heat treatment.
    I seen a few truck frames in scrape welded need I say more.

    Dave
    THAT^^^^ Like Dave said .. that 12V said.


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  9. #7
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    Re: Welding on a truck frame

    You also have to use the right rods or wire. I worked at a place that built winch trucks. Mostly bolted but some welding near the back similar to a dump truck. 90 deg. mini mag drill to drill frames was the cats azz. It fit between the tires and frame. They also had a 120 Kingsland ironworker. Nice machine but the hole punch kind of sucked. If you wanted to lower the punch to your center punch mark you had to put it in jog mode and then switch back to punch mode. Mostly we lifted the plate up to the punch and then punched the hole. Problem was the long frame plates were a little heavy to do that for 1 person. They had a tapered reamer in an air drill if the holes were a little off though.

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    Re: Welding on a truck frame

    The steel on truck frames are 120ksi
    You can not weld this type of steel.
    The highest strength steel you can weld is about 45ksi this type of steel is found on metal buildings.

    Dave

    Quote Originally Posted by Welder Dave View Post
    You also have to use the right rods or wire. I worked at a place that built winch trucks. Mostly bolted but some welding near the back similar to a dump truck. 90 deg. mini mag drill to drill frames was the cats azz. It fit between the tires and frame. They also had a 120 Kingsland ironworker. Nice machine but the hole punch kind of sucked. If you wanted to lower the punch to your center punch mark you had to put it in jog mode and then switch back to punch mode. Mostly we lifted the plate up to the punch and then punched the hole. Problem was the long frame plates were a little heavy to do that for 1 person. They had a tapered reamer in an air drill if the holes were a little off though.

  11. #9
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    Re: Welding on a truck frame

    Quote Originally Posted by Welder Dave View Post
    You also have to use the right rods or wire. I worked at a place that built winch trucks. Mostly bolted but some welding near the back similar to a dump truck. 90 deg. mini mag drill to drill frames was the cats azz. It fit between the tires and frame. They also had a 120 Kingsland ironworker. Nice machine but the hole punch kind of sucked. If you wanted to lower the punch to your center punch mark you had to put it in jog mode and then switch back to punch mode. Mostly we lifted the plate up to the punch and then punched the hole. Problem was the long frame plates were a little heavy to do that for 1 person. They had a tapered reamer in an air drill if the holes were a little off though.
    In frame work I always drill my holes 1/16" undersize and then ream them to exact size through all the plates, etc. to make sure everything lines up properly and avoid any shear forces on the bolts.

  12. #10
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    Re: Welding on a truck frame

    The welding on the frame is not under much stress. Just to clean up the back end mostly.

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    Re: Welding on a truck frame

    I feel that a large portion of the do not weld stickers are used to discourage the average person from welding things to frames in ways they shouldn’t be. I would venture that most manufacturers have specific welding procedures for welding on frames
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    Re: Welding on a truck frame

    Those same warning stickers also say not to drill the frame either. In reality they are welded on and drilled every day. Drilling and welding on the flanges is generally considered a no-no. Lengthening or shortening is generally done with liner rails and bolted or hucked. Welds are just on the joints.

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    Re: Welding on a truck frame

    Quote Originally Posted by M J D View Post
    Those same warning stickers also say not to drill the frame either. In reality they are welded on and drilled every day. Drilling and welding on the flanges is generally considered a no-no. Lengthening or shortening is generally done with liner rails and bolted or hucked. Welds are just on the joints.
    Most of those stickers state "do not drill flanges" The web is fair game for drilling. But yes to the liner channels for reinforcing cut frames. I've repaired 3 trucks with broken frames, 2 were simple fatigue and one was a bad lift axle installation where the installer scribed the holes deep and hogged out a bunch of holes that didn't match apparently. What a mess.

    I've also done 2 Aluminum frame repairs where the rail broke and we lined it and covered it with channel. Didn't even bother to try to weld the aluminum... Lost cause.

  16. #14
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    Re: Welding on a truck frame

    Quote Originally Posted by 12V71 View Post
    Most of those stickers state "do not drill flanges" The web is fair game for drilling. But yes to the liner channels for reinforcing cut frames. I've repaired 3 trucks with broken frames, 2 were simple fatigue and one was a bad lift axle installation where the installer scribed the holes deep and hogged out a bunch of holes that didn't match apparently. What a mess.

    I've also done 2 Aluminum frame repairs where the rail broke and we lined it and covered it with channel. Didn't even bother to try to weld the aluminum... Lost cause.
    They usually put that sticker directly where one needs to make the cuts. I've never had an issue welding truck frame myself. I've used old frame material for many different things and used regular mig or 7018 with no issues either. That's a far cry from doing a butt weld in the middle length of a frame and calling it a day though.

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