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  1. #1
    Senior Member clasher's Avatar
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    Aluminum chainstay burst

    So, I got a free frame that someone claims water froze in the chainstay and it burst, leaving a small crack. I think is true because the crack has forced some material outwards, and when I took the BB out, water poured out of the frame and all the seat tube was all wet when I took the seatpost out. Anyway, I didn't do it but I since the frame was free I thought it would be worth experimenting with a repair.

    So, anyway. I'd like to repair this frame and ride it as a commuter/round-town bike. By far it's the most new-fangaled bike that I've ever had, and the only aluminum one too. I didn't pay for it so I can't just "Get a new frame" as everyone commonly suggests with these sorts of threads. I'm not sure I'd buy a new aluminum bike in the first place... anywho.

    Here's my plan for the repair.

    Drill stop holes at the ends of the crack to help stop its spread. File away the material that "burst" above the surface when the chainstay opened up.

    Clean off all the surrounding paint and clean the area thoroughly.

    Now, I have either two options. TIG weld the crack and then fabricate a sleeve and then weld the sleeve to the chainstay to reinforce the whole area. Judicious use of heat sink clay would hopefully minimize the damage from heating the frame up with welding.

    The other option is to do the same repair, but using HTS-2000 brazing rods. I like this idea, but they almost seem too good to be true... but I'd basically follow the same procedure as with TIG welding it.

    Here are some pictures:


  2. #2
    Senior Member mudboy's Avatar
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    It's a low-stress area, and if it did fail, it wouldn't be catastrophic (i.e. having you go ass over elbows). I'd just throw some duct tape on it and ride it.
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  3. #3
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    Quote Originally Posted by mudboy View Post
    It's a low-stress area, and if it did fail, it wouldn't be catastrophic (i.e. having you go ass over elbows). I'd just throw some duct tape on it and ride it.
    I'm inclined to agree, but if I was to weld it , I would probally hog the crack out with a small burr to make a groove and then weld it. I can smell the burnt powdercoat from here........blecch! good luck!

  4. #4
    Senior Member clasher's Avatar
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    Clean it out and duct tape it. Got it! Maybe I'll use gorilla tape...

  5. #5
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    It's aluminium, so you can glue to it quite well if you prep it properly.

    I'd grind the damaged portion flat, take the powder coat off all around the tube, etch the aluminium and wrap it in carbon fibre and epoxy - three or four wraps of the tube should do. Probably end up stronger than the original and not too obvious, given the black powder coat.

    This is easy for me to say because I have several types of CF cloth and the appropriate resins in a box in my shed but they are easy to buy from your local fibreglass supplier and they are not that expensive.

  6. #6
    www.markreynoldsfund.org
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    That had to be what happend on the steel parkpre frame I posted about. The tube is split and there appear to be an outward bulge. Never seen it happen before.
    Mudu93

    Please donate to the Mark Reynolds Memorial First Bike Fund at www.markreynoldsfund.org

  7. #7
    Senior Member hotbike's Avatar
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    File it smooth , and wrap fiberglass with epoxy around it. This way, no heat will affect the temper of the tubing.
    http://www.flickr.com/photos/11629987@N02/sets/72157639939606343/

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