JB Wield

Discussion in 'Motorized Bicycle General Discussion' started by AnthonyX99, Mar 12, 2010.

  1. Earthman

    Earthman New Member

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    If you feel adventurous, there's a low-temp brazing rod for aluminum. It melts at 700 deg F so you can use a common propane torch for the heating. The stuff adheres well to clean metal, and is stronger than the base metal. You may be able to clean the original holes, fill them with the brazing material, and then drill and retap the holes. I've used the stuff to make lap joints in aluminum bar stock with good results. Just make sure the metal is clean (degrease it and scuff it up a bit - it doesn't have to be too shiny), don't over heat the metal by keeping the flame moving and only heat until the brazing rod melts (heat the base metal not the rod). The rod will melt when the base metal reaches the correct temp.

    You might be able to find the stuff at HomeDepot. If not, use the following link:

    Hobart 770206 - 8 Pack Aluminum Rods - 18-1/2" Long - Toolfetch.com

    Don't know if this will work, but it may be worth a try if nothing else works.
     
  2. bairdco

    bairdco a guy who makes cool bikes

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    you can use those rods (the trade name is "Alumiweld," available at Harbor Freight) to actually "make" threads.

    i haven't tried it in an engine, but i made some fender struts out of aluminum. i wanted steel eyebolts at the end that bolts to the axle, so i drilled a hole, dropped a piece of alumiweld in, then put the eyebolt in.

    heated it up and when it started to melt, pushed the eyebolt down with pliers, and the alumiweld squished out the top.

    since the bolt is steel, the alumiweld doesn't stick to it, and you can thread the bolt out.
     
  3. caprirs302

    caprirs302 New Member

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    I wasn't joking, I have snapped off two front motor mount bolts right down to the engine, the first I tried to drill out, and couldn't drill on center so my easy out failed miserably. On my new motor, I recently busted another bolt, again flush with the motor. This time I took a dremmel tool and a cutting blade, and cut a small slot across the bolt. I had to cut into the motor just a bit, but you would never notice. The bolt came out with no effort using a screwdriver. I also promptly installed a front motor mount from sick bike parts, instead of continuing to use the stock mounting method. No problems thus far.
     
  4. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    When you are trying to drill the old bolts out, are you using a punch first to make the drill start in the center?

    Try it next time, you can drill anything on center if you use a punch first.
     
  5. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    I am so glad you decided against doing JB Weld sculpture on your block. You have already gained much wisdom, Grasshopper.
     
  6. Drewd

    Drewd New Member

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    Yep, I agree. I've even used it on something that it wasn't intended for, a 4500 shaft horsepower turbine engine that had a crack in it and was leaking oil. The crack was stop drilled and the crack sealed with JB weld. It held until the engine went into overhaul. Yes, this repair was illegal and violated all sorts of FAA airworthiness and military rules but it got us home.
     

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