Butt weld panel gap

Mopar Body and Trim

  1. bob7four

    bob7four Well-Known Member

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    Have a new patch panel fitted up and ready to weld. I flanged the edge of the existing panel and laid the new panel in. My question is what kind of gap should I have between the panels? The gap seems tight so the panels were fit perfectly. Is there tolerances either way? What is too tight and what would be too large?
     
  2. cudascott

    cudascott wish I had a Hemi

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    The gap should be close to thickness of the wire your welding it with.
     
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    • mopar head

      mopar head Well-Known Member

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      No gap on a flange lap.
       
    • Dartnut

      Dartnut Don't hate me because i'm beautiful

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      It sounds like to me that the panel was laid inside of the flange, is that correct?
      That would make it a lap weld, not an open butt weld.
      If this is the case, then the metal where it touches should be flush, and the area where the new panel and the old panel meet at the step should be no more than 1/4'' all of the way around.
      If it is a butt weld, then a gap of about the same size as the wire you are welding it with is the best choice.
      Remember to weld using a series of tacks spaced a foot or so apart and allow for cooling as you go to reduce warping.
      The actual welding takes a long time this way, but it's worth it in the long run.
      Pictures of your project close up would go a long way here......
       
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      • RustyRatRod

        RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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        You're speaking of two different welds in one sentence. Is it a butt weld or a flange weld? The butt weld requires a gap. The flange weld does not. Which is it? It can't be both.
         
      • bob7four

        bob7four Well-Known Member

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        Flange weld... excuse my ignorance. Not all experts here. The edge of the new panel is close to being tight against the top of the flange.
         
      • RustyRatRod

        RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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        Ok. The way "I" weld a flange weld is like the factory did it. I drill holes through the flange and then spot weld to whatever metal the fanged panel is going on.
         
      • 66jim

        66jim Well-Known Member

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        Make sure to address the inside edge of the flange as moisture and debris can collect
        and rust.
         
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        • RustyRatRod

          RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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          Seam sealer!
           
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          • cudascott

            cudascott wish I had a Hemi

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            My bad guess I should have read a bit better
             
          • RustyRatRod

            RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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            You made a mistake not! You were right on target for a butt weld. I said butt.
             
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            • plymouth67

              plymouth67 It be a lot cooler if you did...

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              If your going with a flange style repair then use metal bond epoxy instead of welding it. No warping, no grinding the welds down, very little filler needed after, and the epoxy seals the back side of the repair from ever rusting. Oh yeah it's also about 3 times faster to do...
               
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              • RustyRatRod

                RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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                I've read lots of good reviews about gluing panels on. Who'dathunkit?
                 
              • plymouth67

                plymouth67 It be a lot cooler if you did...

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                It's really the same stuff they have been gluing the tops on the high top conversion vans for like 35 years....you ever seen one of those blow off...lol.
                 
              • RustyRatRod

                RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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                In all honesty, they could probably use silicone calk. I don't think it would ever come off by itself.
                 
              • harrisonm

                harrisonm Well-Known Member

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                Totally agree that bonding is good. However, the panels have to fit really well. The adhesive does a great job but gaps found in a poor fit will greatly reduce the seam's strength.
                 
              • bob7four

                bob7four Well-Known Member

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                To Dartnut... yes panel is laid in the flanged existing metal. Picture is attached.

                20191109_075731.jpg
                 
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                • Dartnut

                  Dartnut Don't hate me because i'm beautiful

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                  Looks good to me.
                  The use of clecos is a great idea!
                   
                • sireland67

                  sireland67 Well-Known Member

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                  It looks like on the right side, the patch panel is actually too high, lay a straight edge, as long as the patch panel is slightly lower you are good to go.
                  And I would also would glue the panel on.
                   
                • Tooljunkie

                  Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                  Guess it depends on the climate. have seen bonded panels rust right off. No experience with only summer driven cars.
                   
                • bob7four

                  bob7four Well-Known Member

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                  Glue and weld? Will the heat from welding affect the glue or is there something that will hold up? The glue would seal that seem nicely.
                   
                • sireland67

                  sireland67 Well-Known Member

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                  They bond a lot of panels OEM
                  You have to stay away from the glue like 2” if welding near it.
                   
                • adriver

                  adriver Blazing Apostle

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                  Lord Fusor "weld through" adhesive.
                  Several types. Designed for spot welding if necessary for new car repairs.
                  Thing is I contacted them re that very thing.
                  As expected, it would take more than a hobbyist spot welder to accomplish it correctly.
                  Bottom line, just use the adhesive sans welding if that is what you want to do.
                   
                • sireland67

                  sireland67 Well-Known Member

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                  Good to know, I used 3M OEM stuff it said stay away 2”
                   
                • plymouth67

                  plymouth67 It be a lot cooler if you did...

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                  I use Lord Fusor products, just put in a wheel arch patch in my son's truck over the weekend with it.
                   
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