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  1. #1
    Senior Member ApolloCVermouth's Avatar
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    Replacing Dropouts

    How hard would it be to replace vertical dropouts with horizontal ones in a typical MTB frame (if there is such a thing). Is this something that someone with no brazing experience should try? How much would the equipment to do this cost? Thanks.

  2. #2
    Older I get, Better I was velonomad's Avatar
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    Difficulty, depends on whether you have a steel frame or aluminum (forget about aluminum), depends on whether the frame has plug, slotted, or breezer type dropouts, depends on whether the dropouts were brazed or welded.
    Cost; Some of us have done it with $40 mapp gas torches but it takes some finesse and jury-rigging to get the dropouts hot enough. Otherwise you spend $300 or more for oxygen/acetylene torches and tanks.

    It isn't rocket science but IMO it isn't a project that most people should do the first time they hold a torch. Saskatoon is a pretty active cycling town. You should be able to find someone local that can do it for you. You may save some money by stripping the paint to bare metal from at least a 8" perimeter of the drop outs prior to having the work done, and repainting the frame yourself afterwards

    To give you an idea of what is involved ,here is a link to a guy who did it quick and dirty and not altogether correctly.

    http://boozhoundlabs.com/stumpy/

  3. #3
    Senior Member ApolloCVermouth's Avatar
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    Thanks for the info and the link. I hadnít realized that the dropouts might be welded. I had hoped that I could just use a hand torch but I guess that would be difficult. Yeah, I know at least one frame builder around here who could do it for not too much money. Just thought it might be an interesting project. Looks like itís out of my league though.

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    Quote Originally Posted by velonomad
    To give you an idea of what is involved ,here is a link to a guy who did it quick and dirty and not altogether correctly. http://boozhoundlabs.com/stumpy/
    "not altogether correctly"? I'm curious what you think he did do correctly.

  5. #5
    Older I get, Better I was velonomad's Avatar
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    Quote Originally Posted by MnHPVA Guy
    "not altogether correctly"? I'm curious what you think he did do correctly.

    You mean this isn't ok? You can't overheat silver flux by 400 deg and use it for bronze?




    I was trying to be tactful and show an example of how beginners make mistakes. . The OP understood what I said and there was no reason for me to verbally trash this guy's effort.

  6. #6
    Senior Member atombikes's Avatar
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    Shoudn't I be able to see at least a little bronze in those joints? Maybe if the picture were taken at a different angle it would be more obvious?
    atombikes

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    Older I get, Better I was velonomad's Avatar
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    Quote Originally Posted by atombikes
    Shoudn't I be able to see at least a little bronze in those joints? Maybe if the picture were taken at a different angle it would be more obvious?
    I don't think he got any bronze in there other than what was left when he pulled out the old drop outs. But it may have been enough to hold the track ends. If you can't be good at least be lucky

  8. #8
    Senior Member ApolloCVermouth's Avatar
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    Quote Originally Posted by velonomad
    Some of us have done it with $40 mapp gas torches but it takes some finesse and jury-rigging to get the dropouts hot enough.
    Just for interest's sake, what sort of jury-rigging might be involved? Thanks.

  9. #9
    Senior Member atombikes's Avatar
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    Quote Originally Posted by ApolloCVermouth
    Just for interest's sake, what sort of jury-rigging might be involved? Thanks.
    I think what velonomad is referring to is placing a heat shield, like a steel plate, behind the dropouts (opposite the torch) to contain more heat.

    I personally have used the bernzomatic model JTH7 torch with mapp gas on dropouts. If it is a cold day and I am working outside, I apply more heat to the joint using a second, ordinary propane torch. Works quite well.
    atombikes

  10. #10
    dangerous with tools halfbiked's Avatar
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    Quote Originally Posted by atombikes
    I personally have used the bernzomatic model JTH7 torch with mapp gas on dropouts. If it is a cold day and I am working outside, I apply more heat to the joint using a second, ordinary propane torch. Works quite well.
    Excellent!! I was wondering if that would be effective.

  11. #11
    Older I get, Better I was velonomad's Avatar
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    what atombikes said

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    You want it white hot, cut a soft fire brick in half hollow out a place for the thing you want heated, and have a 1" hole in the side of the brick for the torch, wire it back together, and heat through the hole. You need to be able to get at it once it is hot so make the straps just a few wraps you can joggle apart.

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    By the way, it should be pretty obvious if it has been welded.

  14. #14
    Older I get, Better I was velonomad's Avatar
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    Quote Originally Posted by Peterpan1
    You want it white hot, cut a soft fire brick in half hollow out a place for the thing you want heated, and have a 1" hole in the side of the brick for the torch, wire it back together, and heat through the hole. You need to be able to get at it once it is hot so make the straps just a few wraps you can joggle apart.

    Which filler have you been using at "white hot"?

  15. #15
    jsn
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    Hey guys,

    That example is from my site and I am the beginner you speak of

    There is some question as to whether there was any bronze flowing into the joint when it was brazed. I assure you there was, it just flowed maybe too well and didn't build up any kind of fillet.

    IMHO the main thing I did wrong was braze the dropouts crooked! And maybe not use the "proper" brazing rod.

    Unfortunately I cannot attest to the long term durability of this work because the bike was stolen in New York.

    jsn

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