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  1. #1
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    Stripped rear derailer thread

    So I picked up a mountain bike from a local auction for $50. It was missing a seat and the rear derailer was bent and broken off. At the time the threads on the hanger where the rear derailer attaches worked, though they were pretty messed up. After messing with it to much, and trying to re tap the hole it became to stripped to use.

    So I have this nice new bike that's all cleaned up, new break pads, new seat etc. .. but I can't attach the rear derailer.

    I can't just drill out the hole and use a bigger bolt because the the bolt on the derailer is a special shape, and part of a berring.

    The best fix I've found after searching online are these coil thread repair inserts. FIX-A-THRED, Helicoil are two brands that I've found. Has anyone has any experience with these?

    The only problem is this was supose to be a cheap bike and a helicoil kit is around $20. So I'm looking for other suggestions on how to fix this.

    I have a tap that is the right size, but I don't have access to any sort of welder. Is there any other material that I could plug the hole up with before I drill it out and re-tap it. Polyester resin? Solder? Anyway thanks in advance.


    eric

  2. #2
    The Red Lantern Rev.Chuck's Avatar
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    If it has horizontal dropouts you could whack the hanger off and make a single speed out of it.
    Both of the repairs work, I would spend the money and get one of them done. I like the helicoil better but you need a wide dropout for it to work well.
    You could braze in the hole if it is steel. If you fluxed it then heated just enough to get flow, the brass would fill the threads. You could then retap. this would probably work.
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  3. #3
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    Quote Originally Posted by Rev.Chuck
    If it has horizontal dropouts you could whack the hanger off and make a single speed out of it.
    Both of the repairs work, I would spend the money and get one of them done. I like the helicoil better but you need a wide dropout for it to work well.
    You could braze in the hole if it is steel. If you fluxed it then heated just enough to get flow, the brass would fill the threads. You could then retap. this would probably work.

    What do you mean a wide dropout? What would i need to "braze" the hole with brass?

    eric

  4. #4
    Senior Member miamijim's Avatar
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    Drill out the hanger. Insert a commercially available threaded insert designed specificaly for this application (check LBS). The insert installs from behind. When the derailleur is threaded in it pulls and holds the insert in place.

    option 2. Depending on the hanger style you can cut it off and use a 'bolt-on' hanger. Check your LBS for the hanger.
    WWW.CYCLESPEUGEOT.COM 2005 Pinarello Dogma; 1991 Paramount PDG 70 Mtb; 1976? AD Vent Noir; 1989 LeMond Maillot Juane F&F; 1993? Basso GAP F&F; 1989 Terry Symmetry; 2003 Trek 4700 Mtb; 1983 Vitus 979

  5. #5
    The Red Lantern Rev.Chuck's Avatar
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    Man, I didn't even think of that. Miamijim has it, use the bolt on hanger, if it will fit. That would only be a couple of bucks.
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  6. #6
    Can't ride enough! Da Tinker's Avatar
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    Or use a drop saver from Wheels http://wheelsmfg.com/p_tools_other.html
    Drill out the trashed threads and inset the threaded adapter.
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  7. #7
    sch
    sch is offline
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    Variation on the same theme: www.loosescrews.com search for part
    # WB-DS2. Probably sourced from Wheelsmith. $9.50 for a nut. If you
    have a tap, a lathe, and drill you could make one.... Steve

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