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Filling surface cracks in aluminum

Discussion in 'General Classic Motorcycle Discussion' started by swordfish1, Jan 4, 2014.

  1. swordfish1


    Jul 31, 2013
    I have a 68 G15cs with surface cracks on the timing cover. Would like to fill these with an aluminum resin putty that has a high alum content. The theory being the resin fills the crack dries and then can be burnished out. Any suggestions or help would be greatly appreciated. Thanks in advance -reading these forum questions is very informative.
  2. dave M

    dave M

    Oct 19, 2005
    Mark, I would use one of the plastic steel products like JB weld and add in some alloy filings that you can make yourself by filing a piece of scap alloy or else ask your friendly machine shop/ fabricator for a small bag full.
  3. madass140

    madass140 VIP MEMBER

    Nov 6, 2011
    if the surface cracks are very fine , then JB weld or Devcon or any of these thick 2 pack brews will not stay in the crack, you will have a hard time forcing it in and I doubt that it will stay there .
  4. texasSlick

    texasSlick VIP MEMBER

    Jan 2, 2013
    +1. Best to TIG weld, then sand and polish.
  5. Jeandr


    Jan 22, 2008
    The epoxies are never the same color and will not polish like metal. Even welding may not yield the same finish. The metal to be welded may not be "clean" when heated by the welding torch and it may boilt out some impurities giving a bad finish to the part.

    I needed filling up some holes in a Suzuki water buffalo front drum backing plate, the first guy who tried was an amateur and he made it worse, so I filled it in with epoxy and it showed up like a map once it was sanded and polished. I had it welded by a pro and while he did his best to fill it in, the crappy base metal boiled out a lot of crap and it did not look any better than before so I again filled it with epoxy, sanded it smooth and painted it black, now it looks perfect 8)

  6. Bernhard


    Apr 20, 2011
    re; "The theory being the resin fills the crack dries and then can be burnished out."

    I would ask, can I come and watch you, as I have never see anybody try to get the same colour as alloy with resin filler before.

    You may get an alloy filler rod from sif bronze welding- they do lots of alloy rods, But use the right heat torch to fill the gaps after you have ground the outer skin off the alloy beforehand – or it simply will not stick :!:

    http://www.bing.com/search?q=sif+bronze ... ORM=IE8SRC
  7. HoveToo


    Jan 1, 2012
    Would it be possible to lightly peen the cracks and then polish it back to restore the finish. At least then you are using the same metal. Filing may also work by rolling metal into the crack.
    Cheers, Ian
  8. concours

    concours VIP MEMBER

    Dec 29, 2011
    Any pictures? When you say surface cracks.. you mean the imperfections formed during the (too rapid) cooling of the cast part?
  9. swordfish1


    Jul 31, 2013
    Thanks Ian/hove to the preening idea worked like a champ - again thanks much bye the bye where is Hove located in England? Mark kulik
  10. HoveToo


    Jan 1, 2012
    Hi Mark, I'm glad it worked... Hove is part of Brighton, about 50 miles due south of London on a rather stormy seaside today... Ian

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