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Welding on a cracked tranny

Discussion in 'The Garage' started by MontanaLifted, Nov 16, 2003.

  1. MontanaLifted

    MontanaLifted 1/2 ton status

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    Has anyone had any experience with welding on the crappy pot metal they use for transmission cases? After months of tracing problems and fixing everything but the problem I finally ran some dye through it and turns out I have a hairline crack on the rear of my transmission.

    -What do you guys think of welding this problem. ARC or MIG?

    -Will JB Weld work if I do some grinding first?

    -How about brazing?

    I think brazing would be the best but I don't want to burn a hole through and be screwed.
    It's a damn shame because I can't kill this tranny by romping on it.

    Thanks,
    ML
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  2. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

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    I wouldn't call it pot metal. It's aluminum and I'd tig weld it.
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    You can try welding it, but I'd say the cracking will get worse. The heat from the welding causes rapid expansion and cast aluminum is pretty rigid and somewhat brittle. I've welded cast aluminum before and the failure rate was high...

    Also cast aluminum is pretty porous, so you'll have one hell of a time getting the crack cleaned and prepped good enough to keep the impurities out.

    I'd find another case and swap the guts...it'll be less frustration and probably less work. (because you'll lkely have to swap guts whether you weld it or not.)

    Rene
     
  4. mastercraftkpk

    mastercraftkpk 1/2 ton status

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    I have had success MIG welding aluminium transmissions. It wasn't pretty, but it held well. As a precaution, I left the tranny fluid in in order to act as a "coolant" and then changed fluid. Caution: be careful because you will get a LOT of spatter.

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  5. ntsqd

    ntsqd 1/2 ton status

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    The best way to weld it is to strip the guts out of it and have the case cleaned by a trans shop. Drill the ends of the crack(s) with a small drill to keeep the cracks from continuing and V the crack nearly all the way thru. Hit the V'd crack and the area around it, on both sides, with Brake Cleaner. You'll want to heat the whole case to 300-400 degrees b4 welding it. Use a stainless steel bristle brush (NOT Carbon steel) and thoroughly scrub the weld zone. MIG or TIG will work equally well. Weld past the holes you drilled by a little bit. Then reheat the case to ~300 degrees and allow to cool in still air. The longer it takes to cool the better. Then you can stuff all of the guts back in it.
    I used to repair a lot of aluminum Sprint Car cyl heads this way.

    Seems to me it would be easier to find another case than go thru all of that work.
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    [ QUOTE ]


    Seems to me it would be easier to find another case than go thru all of that work.

    [/ QUOTE ]

    Agreed... /forums/images/graemlins/thumb.gif /forums/images/graemlins/deal.gif

    Rene
     
  7. MontanaLifted

    MontanaLifted 1/2 ton status

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    Righty,

    Thanks guys.

    ML...
     
  8. limey

    limey 1/2 ton status

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    they make a replacement bellhousing but i cant find the link any more. you cut the bellhousing off smooth with the pump boltsanp bolt a thicker one on using the pump bolts. i think it was the hotrod guys doing it because their bigblocks kept breaking the housings. o will see if i can find the link laters.
     

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