Mig welding mild steel to cast iron

  1. ross_m Member

    Messages:
    66
    Scotland
    Hello, I have searched the forum and have not found a definitive answer

    I need to weld mild steel brackets to a cast iron Honda CR-V steering knuckle (as secondary mounting for rose jointed steering tie rod ends) see example of said knuckle in this link:

    https://www.google.com/url?sa=i&url=https://www.amazon.com/Premium-Steering-Knuckle-Replacement-2007-2009/dp/B082SGQZT7&psig=AOvVaw2Jes8oZrIO2SERl1jx9mSF&ust=1595521231808000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCMi4rfeh4eoCFQAAAAAdAAAAABAp

    A local motorsport preparation company used normal mig welding wire for this job on their car and hasn't yet had any issues although I have read all over the place that this isn't sufficient for a safety critical item..

    Any advice on type of mig wire to use and prep, for example pre heating, would be much appreciated

    Thanks
     
  2. tom2207 Member

    Messages:
    1,604
    Location:
    uk northern ireland
    Sure its not cast steel ?
    Either way , with all respect I wouldnt be doing it for you , and the fact your having to ask would tend to suggest you shouldnt either.
     
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  3. minimutly Member

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    1,120
    Location:
    Pembrokeshire Wales
    Guaranteed cast or forged steel, if you can preheat it you will have a better chance of success.
     
    metalmelt likes this.
  4. TechnicAl

    TechnicAl Member

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    7,477
    Location:
    Rotherham
    If it is mild steel to cast iron. Standard mild steel MIG wire (G3Si1) will absorb Carbon from the Cast Iron and you will achieve a very brittle weld. The wire grade usually used for these types of joints is the Nickel / Iron 55/45 which is very very expensive...I dont know the prices these days but you will be looking at £500 - £800 for a 15Kg reel.
     
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  5. ross_m Member

    Messages:
    66
    Scotland
    I dont understand this reply. If everyone thought like this nobody would try or learn anything. There would be a time when an expert in this field didnt know the answer..

    Its cast iron. Also says in the link I posted
     
  6. ross_m Member

    Messages:
    66
    Scotland
    Thanks for that. Interesting
     
  7. ross_m Member

    Messages:
    66
    Scotland
    In the link it says cast iron.
     
  8. Cobbler

    Cobbler Codger bodger

    Messages:
    5,034
    Location:
    Gloucestershire UK
    I know it says cast iron, but I bet it isn’t. Cast iron wouldn’t be strong enough, it’s cast steel or a forging. I’m no expert but I think cast iron would shatter.
     
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  9. tom2207 Member

    Messages:
    1,604
    Location:
    uk northern ireland
    Theres a time for us all to learn things , and theres a time for the things we have learned to guide us ,
    I really doubt its cast iron , how ever , if your sure it is , it can be .
    You dont know what to weld it with to get decent results , there for i respectfully suggest you dont try to learn on something thats tied in to brakes and steering , sort of safety critical parts.
    How ever if you think its wise to do so , go on ahead
    What could possibly go wrong.
     
    wyn likes this.
  10. gt6s Member

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    784
    Location:
    Newtownards Co Down Northern Ireland
    CI ? Doubt it.
     
  11. Robert.

    Robert. New Member

    Messages:
    105
    Location:
    South East
    A complex a shape and requires structural strength ,that can only be cast steel . It is not cast iron , I do not care what an Amazon advert says , I have spent many years dealing with both materials in many engineering roles ... I wouldn't even need to spark test that part to already know it is with no doubt cast steel .
     
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  12. doubleboost

    doubleboost Member

    Messages:
    2,957
    Location:
    Newcastle upon Tyne England
    All the steering knuckles i have played with are cast steel
    A weld on this component would be a MOT fail
    On a competition vehicle i would weld it no problem
    Do a test weld on a scrap hub then test it with a big hammer
     
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  13. Steveblade

    Steveblade Member

    Messages:
    133
    Location:
    West midlands
    Also just saying someone has mig welded to it says it not cast iron. Take the hint its not cast iron its forged steel. Also even though it seems to be weldable its a "steering component". Does it have a plastic cup and rubber seal, what happens if the weld fails, is there an alternate way to join the parts you need to. Is it a track rod end ? Or inner joint on the rack?

    Just seen the part, Bolt on to it job done
     
  14. minimutly Member

    Messages:
    1,120
    Location:
    Pembrokeshire Wales
    Autograss racing is as tough a motorsport as you'll get. Steering hubs are regularly cut and mig welded to repurpose them. They are never cast iron, they sometimes do break, but only if hit by another car. I have welded thesemyself (not the Honda one in question), I strongly suggest you preheat and cool slowly.
    If this was a roadd car I would agree with someone who says don't do it...
     
  15. Steveblade

    Steveblade Member

    Messages:
    133
    Location:
    West midlands
    I can think of an easy low tech way you can proove one way or the other what these are made of. Beat the thing , an old one, to death with a big heafty lump hammer, you should be able to bend it if you give it the beans. Now try a similar effort against a brake disc off the same car, I think you'll notice a difference. The one that smashes into pieces is cast iron, its brittle compared to steels.
     
  16. spencer 427 Member

    Messages:
    6,924
    Location:
    uk colchester
    A simple spark test would determine what material it is..I would definitely say cast steel. Anything to do with a miss match of materials is and can be a pain...but I definitely wouldn't be doing it on steering components.
     
  17. Matchless

    Matchless Member

    Messages:
    1,052
    Location:
    Essex UK
    Do as I say, not as I do, so, don't weld steering components, now I have done it a few times but I am a self confessed bodger, I upgraded my first motorcycle transporting camper, a Bedford CF1 coach built bus to LDV disc brakes and a BMW E36 PAS rack, at first it had bad bump steer, learnt a lot that week, lots of modding later it handled well, for a CF1 bus, eventually fitted a BMW 732i or 635csi engine and auto box, anyhow my mig welded components were tested when it ended it's life at a Christmas van banger meeting, it was wrecked but my welded steering arms, rack mounts, steering rod extensions etc. did not break, one track rod snapped but at a threaded part, that said I did not weld bits once, usually made several passes after V grinding to start with, and where possible ran a strip of steel bridging any join, 100 years ago I used to lengthen mini bottom arms using an arc welder but with strips of mild in the channel of the arm, ok, a good 50 years ago, I am very much a belt and braces style of bodger, it is safer that way!

    Only had one potentially nasty steering failure, drop arm broke clean off the steering box shaft as I did a U turn in Waltham Way, where it is dual carriageway, not so easy to move a J2 van with zero steering on full lock! and no I had not welded it, and did not weld it after, I scrapped the van.
     
  18. Matchless

    Matchless Member

    Messages:
    1,052
    Location:
    Essex UK
    cast iron does not bend, it shatters, must be cast or forged steel to be malleable, no cast iron on vehicle suspension or steering components, but it is a common mistake to call it cast iron,
     
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  19. ross_m Member

    Messages:
    66
    Scotland
    All comments appreciated. It's strange that so much literature refers to many cars steering knuckles as being cast iron if they are indeed not. And Im not just talking about for sale ads from questionable sites.

    I will do the spark/hammer test out of interest and take it from there but would like to believe it's cast steel after all these comments
     
  20. doubleboost

    doubleboost Member

    Messages:
    2,957
    Location:
    Newcastle upon Tyne England
    Done a few mini bottom arms in my time
     
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