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Mig welding auto panels in Place on vehicle

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  • Mig welding auto panels in Place on vehicle

    hey guys,,,I know this is an old subject for most all of you but,,
    I am attempting my first auto panel restoration and I need some basic info.
    I want to cut old panel sections out on the vehicle and mig weld the new panel on . I have obviously never done this before.
    I have asked this question once before and many ideas were presented back to me concerning whether or not to leave the Battery connected while welding. However,,, I did not get any concrete tips on doing the welding on the panels in place on the vehicle.

    I assume there is no problem doing so given all the general precautions regarding keeping the gas tank well insulated from sparks, do not weld if fumes are present,use some backing materials to prevent excess sparking,etc.

    Any professional input is welcome.

    Oh yeah,,,humor and sarcasm is OK too,,, as long as the advice is good!

    Real determined to progress my skills!!!

    Miller Dynasty 200DX Tig/arc
    Millermatic 180 Mig
    Miller 375 Extreme Plasma
    Victor OX/acetylene
    Cutting and grinding tools enough for newby shop

  • #2
    No it shouldn't be a problem as long as you follow all of the precautions that you mentioned.
    Body shops weld on vehicles all the time unless the panel is a bolt on replacement, or plastic!!!
    Good luck, have fun and stay safe!
    at home:
    2012 325 Trailblazer EFI with Excel power
    2007 302 Trailblazer with the Robin SOLD
    2008 Suitcase 12RC
    Spoolmatic 30A
    2009 Dynasty 200DX
    2000 XMT 304
    2008 Thermal Dynamics Cutmaster 52
    Sold:MM 251
    Sold:CST 280

    at work:
    Invision 350MP
    Dynasty 350
    Millermatic 350P
    Retired:Shopmaster 300 with a HF-251


    • #3
      I have welded sub-frames on my Mustang without any problem. I followed the same safety precautions that you mention. I disconnected the battery because I was worried about having some affect on the car's computer or electrical system. I would recommend, though you probably already realize, that you should be careful to get a good ground as a further precaution in protecting the electrical system.


      • #4
        Check out Miller's archives for an article written by one of the NASCAR teams regarding tack welding body panels.

        Has some good tips regarding volt setting and wfs.
        Syncrowave 250 DX Tigrunner
        Dynasty 200 DX
        Miller XMT 304 w/714D Feeder & Optima Control
        Miller MM 251 w/Q300 & 30A SG
        Hobart HH187
        Dialarc 250 AC/DC
        Hypertherm PM 600 & 1250
        Wilton 7"x12" bandsaw
        PC Dry Cut Saw, Dewalt Chop Saw
        Milwaukee 8" Metal Cut Saw, Milwaukee Portaband.
        Thermco and Smith (2) Gas Mixers
        More grinders than hands


        • #5
          Are you replacing full panels or just patching them in? Give us more details so we can help better with your questions. Some pictures would be helpful too.

          If you are replacing body panels such as quarter panels, rear body panel or trunk floor some precautions need to be made to insure proper fit up before welding. If that is the case I will go into more detail but if you are just patching panels, work in as small an area as you can and stagger your welds through out the panel to minimize warpage. Always check behind the panel you are working on as many of them have sound deadeners, insulation, seam sealers and other flammable materials glued to them. A fire extinguisher is a must have item when doing this kind of work, doesn't hurt to have a fireman (extra person just in case) standing near by either. Another suggestion is to get some Cleco fasteners to hold your panels in place while you do your fit up before weld it out. If you don't know what Cleco's are I will go into more detail there as well.

          Door skins are different in the way they are installed as well and can also give more detail if necessary.

          One big mistake I see quite often when working on body panels is that the car is jacked up on one corner where the work is being performed. All chassis will flex when jacked and the entire vehicle needs to be placed on stands UNDER the suspension (all 4 wheels) so that the car sits natural as if it where on the ground. If the car is not supported in this manner the once nice fitting panel will not fit so nice when placed back on the ground.

          BTW, preparation is the key to a good fit up and final end product, it is where the most time should be spent. Trying to cut corners will only come back and make ten times more work to straighten out what should have been done to begin with.
          Last edited by dabar39; 09-19-2008, 06:20 PM.
          If necessity is the Mother of Invention, I must be the Father of Desperation!

          sigpicJohn Blewett III 10-22-73 to 8-16-07
          Another racing great gone but not to be forgotten.