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How to glue alu to alu

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  • How to glue alu to alu

    I have modified a carby to suit my bike. A new air box adapter was made and small plug to block a relocated vent. Used 2011 T3. What is the best way to glue the items in place ? Epoxy resin or other ?



    End result will look like this ...


    Last edited by TR; 11-10-2009, 07:30 AM.

  • #2
    From my limited experience there can be problems getting a 100% glue joint on aluminium.Possibly one of the Loctite products would do the trick,but I'd back it up with a small bolt each side or three equally spaced round it and tapped into the carb body.

    Allan

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    • #3
      Epoxy will work well but it must be applied in a special way. The problem with aluminium is that even if cleaned to bare metal it instantly forms a one molecule thick coat of aluminum oxide. This is not a well fixed surface to form a bond. The trick is to dissolve a small amount of the resin (not the hardener) in a small amount of acetone. Use this mixture with some wet/dry sand paper to abrade the already cleaned surfaces immediately before applying the epoxy. Give a couple of minutes for the acetone to evaporate. The residual epoxy left when the acetone evaporates will prevent oxidation of the base metal and will produce a full strength bond.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        How thin is the boss on the carb ?

        Maybe an option (as aluminum is hard to bond)
        is to carve a new adapter on the lathe, and
        make it a interference fit on the carb boss,
        heating the new adapter in the oven, and shrink
        fitting it on.

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        • #5
          Another vote for Loc-tite. #620

          http://www.midwayusa.com/viewproduct...tnumber=171860

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          • #6
            Originally posted by digger_doug
            How thin is the boss on the carb ?

            Maybe an option (as aluminum is hard to bond)
            is to carve a new adapter on the lathe, and
            make it a interference fit on the carb boss,
            heating the new adapter in the oven, and shrink
            fitting it on.
            Might just do that. This is a prototype adapter. I'll use some 6061 instead.

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            • #7
              Another vote for green loctite. If it is fresh, it will bond in 10 seconds.
              Super glue might be too brittle for this.

              --Doozer
              DZER

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              • #8
                i'd probably shoot for an interference fit between the mating parts, use some loctite and poke a few holes and press fit a few dowel pins radially through both pieces to make sure that it's not going anywhere.

                motors shake a lot. vibrations of that magnitude can make stuff spontaneously detach itself from the rest of the motor, which may effectively render your air cleaner pointless as any opening between it and where it mates with the carburetor is an open door for dirt to get into the carburetor and/or engine and wreak havoc inside...

                ideally, i'd probably TIG the two pieces together, but i can't weld aluminum to save my own life...
                -paul

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                • #9
                  I did that same modification to install a CV40 Keihin carburetor from a later Harley Evolution onto a 1982 Harley Shovelhead. I made my own adapter with a press fit and used red Loctite to hold it. I no longer own the bike but it was still on there after ten years. The pattern I used was for a two-bolt flange but the idea is the same.

                  If you don't have a press fit, you might want to make another adapter that presses on. If you do that, then the purpose of Loctite or Epoxy would only be to seal any possible imperfections that could cause a leak.

                  IIRC, I used about .004 press fit. The surface of the carburetor was irregular and it went on nicely with my old Chinese press.

                  On a Harley Shovelhead, there are places to add brackets to support the carburetor. This is advisable to retain the unit in any case.

                  Edit: I've done several of these in the past few years. Here's a picture of oneof them. The adaptor is on the right side. The CV carburetors are a vey fine unit.





                  .
                  Last edited by gnm109; 11-10-2009, 12:15 PM.

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