Welding metal where the rear of the surface is rusty...

  1. BritishLeylandLover

    BritishLeylandLover New Member

    Messages:
    9
    Location:
    Nottingham
    Currently welding my old Land Rover chassis, which is rusting from the inside, if you can't clean the back of the metal easily and only clean up the front surface where you are welding will the poor rear surface affect the weld? Thanks.
     
    • image.jpg
    • image.jpg
    Shoggi likes this.
  2. Shoggi

    Shoggi Member

    Messages:
    201
    Location:
    Bradford west yorkshire
    Welcome
    That's a good question I have some chassis work to do on my pajero and that's rusted inside the chassis
    I think you will get some good advice soon
     
    BritishLeylandLover likes this.
  3. gaz1

    gaz1 Forum Supporter

    Messages:
    9,108
    Location:
    westyorkshire
    you can clean the front not a problem to weld on unless the back has rusted enough so that when you weld the heat and metal will melt the steel too much creating a big hole

    hence you get a blow through when trying to weld it
     
    BritishLeylandLover likes this.
  4. penfold

    penfold Ambassador plenipotentiary

    Messages:
    2,119
    Location:
    Argyll and Bute, God's own country.
    What are you asking? The rust won't really affect the welding unless the chassis has got so thin you blow through it, it will however mean the chassis will continue to rust if you don't treat it.
     
    BritishLeylandLover likes this.
  5. Burdekin

    Burdekin Chief Bodger

    Messages:
    4,817
    Location:
    Aberdeen
    Grind an edge into the rail aperture for good penetration and clean the inside with some sandpaper. Any rust/muck will come through the weld so drill out the pin hole and reweld those bits if necessary.
     
    BritishLeylandLover likes this.
  6. BritishLeylandLover

    BritishLeylandLover New Member

    Messages:
    9
    Location:
    Nottingham
    Bloke walking past with his dog reckoned any rust on the back of the metal will come back through the weld from behind making the weld "bubbly and porous" ?
     
  7. Burdekin

    Burdekin Chief Bodger

    Messages:
    4,817
    Location:
    Aberdeen
    You'll clean it up well enough with some 80grit sandpaper but you might get the odd bit of muck coming through still. Main thing is to get full pen for strength, the odd pin hole just needs filling so they don't become wee rust holes later on.
     
    BritishLeylandLover likes this.
  8. Only if you are doing butt welds
     
  9. BritishLeylandLover

    BritishLeylandLover New Member

    Messages:
    9
    Location:
    Nottingham
    They are butt welds....
     
  10. Right, the danger with contamination on the reverse side is it will get pulled into the molten weld pool, if it's dry rust you will probably experience arc instability/spatter etc. If it's wet/damp you will get severe porosity
     
  11. BritishLeylandLover

    BritishLeylandLover New Member

    Messages:
    9
    Location:
    Nottingham
    Thanks the car was put away dry in June into my dry heated garage so I'd assume it's bone dry, the spatter your referring to I'd assume that I wouldn't see? As it would be inside the box section as the rust "pings" off from the heat?. The rusty sections were cut out until I hit decent steel new sections butt welded in and then the joins fish plated over, should I be worried do you think?
     
  12. Burdekin

    Burdekin Chief Bodger

    Messages:
    4,817
    Location:
    Aberdeen
    If it's just surface rust then it's not going to be a problem, if they are rotten then it's the scale of the fix is the problem.

    A couple of pics on my thread of doing some chassis stuff. http://www.mig-welding.co.uk/forum/threads/replacing-rusty-bits.65628/ Chassis welding is pretty straight forward as it's heavier gauge so nice and easy to weld.
     
    slim_boy_fat likes this.
  13. tinker jim Member

    Messages:
    207
    Location:
    birminham
    You'll know when you hit serious rust with the weld pool it will spit right back at you as said above there''s surface rust not a problem and there's rot which should be cut out anyway.
     
    Shedendman likes this.
Advertisements