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  1. #1
    Master of the Face Plant
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    Disk brake mount on a Pre-War frame.

    I am currently working on a 1936 Elgin frame that I plan to modify. I have already cold set the frame to 135mm spacing and re-aligned the dropouts. I plan to braze on a disk brake mount but there is no way I can afford to pay for a jig to align it. I thought it may be possible to use a disk wheel and clamp a caliper with the adaptor and bolt that to the braze on bracket. Have any of you been able to mount disk brake tabs without using a pro jig? Are there any DIY ideas for this? I just can't justify spending the money for one job.
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  2. #2
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    What you are thinking sounds about right. I've done one that way.
    I also made a jig with a pice of treaded rod and a thick piece of aluminum. Just put the rod in the dropouts, drilled the aluminum for the rod and then lined it up with some tabs on a frame I had, tapped holes in the aluminum and used that.

    Hope that makes sense?

    You just have to be careful and make sure you miter the tab as needed. But you should be able to do it without a jig.

  3. #3
    Master of the Face Plant
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    Thanks, That kinda what I was thinking too. I have a beefy mount on the way and the bolt holes are slotted so that should give me a little room for error. I have only done brazing once before so chances are I will burn my shop down. Should be fun!
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  4. #4
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    You could make a simple jig for next to nothing.
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  5. #5
    RCP Fabrication
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    my first disc brake fixture was hacksawed out of a piece of 3/8" aluminum.

  6. #6
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    Quote Originally Posted by sandmangts View Post
    I am currently working on a 1936 Elgin frame that I plan to modify. I have already cold set the frame to 135mm spacing and re-aligned the dropouts. I plan to braze on a disk brake mount but there is no way I can afford to pay for a jig to align it. I thought it may be possible to use a disk wheel and clamp a caliper with the adaptor and bolt that to the braze on bracket. Have any of you been able to mount disk brake tabs without using a pro jig? Are there any DIY ideas for this? I just can't justify spending the money for one job.
    Use an Avid BB7.

    Put a wheel w/ rotor in the frame.
    Bolt the BB7 to your disc tab.
    Position the caliper over the rotor and clamp in place with the pad adjuster knobs.
    Tack the tab to the frame.

    Lennard Zinn did this ~2000 and a friend and I did it on my frame shortly after. Made a template for fitting the tab from cardboard.
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  7. #7
    Master of the Face Plant
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    Quote Originally Posted by shiggy View Post
    Use an Avid BB7.

    Put a wheel w/ rotor in the frame.
    Bolt the BB7 to your disc tab.
    Position the caliper over the rotor and clamp in place with the pad adjuster knobs.
    Tack the tab to the frame.

    Lennard Zinn did this ~2000 and a friend and I did it on my frame shortly after. Made a template for fitting the tab from cardboard.
    Awesome, thats exactly what I was thinking of doing. I dont have a bb7 but I should be able to do it with a cheap tektro using a rubber band to clamp the caliper. I thought of doing it with a hope mini and just using a rubber band to hold the lever but then I thought heat may transfer to the hydro fluid. Bad idea. Anyway, thanks for the input. I would like to see pics of your setups. Here is my first attempt at brazing. Not bad considering I have never done it and I learned from Youtube.


    Here is the frame before I blasted it.
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  8. #8
    Natural Born Killer
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    Looks like a great project! I know where one of those frames sits...as a lawn ornament...in my sister's yard...it was my Dad's bike.
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  9. #9
    Master of the Face Plant
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    Quote Originally Posted by nemhed View Post
    Looks like a great project! I know where one of those frames sits...as a lawn ornament...in my sister's yard...it was my Dad's bike.
    Save it! All of these started that way.




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  10. #10
    FKA Malibu412
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    What about a gusset between the chain and seat stay when adding brake tabs to these older frames? Is it recommended?
    "I love the bike. It's my meditation. I think I'm bike-sexual." -Robin Williams

  11. #11
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by Malibu412 View Post
    What about a gusset between the chain and seat stay when adding brake tabs to these older frames? Is it recommended?
    A brace tube is a good idea.
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  12. #12
    Master of the Face Plant
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    I plan to use the same tubing I used already to brace the chain and seat stay. I wonder, should I do it on both sides or just the side with the disk mount?
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  13. #13
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    Quote Originally Posted by shiggy View Post
    Use an Avid BB7.

    Put a wheel w/ rotor in the frame.
    Bolt the BB7 to your disc tab.
    Position the caliper over the rotor and clamp in place with the pad adjuster knobs.
    Tack the tab to the frame.

    Lennard Zinn did this ~2000 and a friend and I did it on my frame shortly after. Made a template for fitting the tab from cardboard.
    I agree with the technique, but I would avoid the use of a BB7 because of those PITA CPS washers. If the washers aren't lined up (the caliper in plane with the mount) then you might tack the mount on crooked which could cause problems if you ever use a non-Avid brake.
    Don't you hate it when a sentence doesn't end the way you think it octopus?

  14. #14
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by zebrahum View Post
    I agree with the technique, but I would avoid the use of a BB7 because of those PITA CPS washers. If the washers aren't lined up (the caliper in plane with the mount) then you might tack the mount on crooked which could cause problems if you ever use a non-Avid brake.
    You could have a similar problem with any brake that is not IS specific.

    Just take the brake off of an existing bike and the caliper will be properly aligned on the IS bracket.
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  15. #15
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    Quote Originally Posted by shiggy View Post
    You could have a similar problem with any brake that is not IS specific.

    Just take the brake off of an existing bike and the caliper will be properly aligned on the IS bracket.
    That would be a good work-around. So long as you don't grab a BB7 out of the box and expect it to be mounted straight right away.
    Don't you hate it when a sentence doesn't end the way you think it octopus?

  16. #16
    Master of the Face Plant
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    Quote Originally Posted by shiggy View Post
    You could have a similar problem with any brake that is not IS specific.

    Just take the brake off of an existing bike and the caliper will be properly aligned on the IS bracket.
    Good Point. I suppose i could just use my Hope brakes and just tack the bracket on and then braze it after pulling the brake off. If it ends up a little off I could just face it or use a shim.
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  17. #17
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by sandmangts View Post
    Good Point. I suppose i could just use my Hope brakes and just tack the bracket on and then braze it after pulling the brake off. If it ends up a little off I could just face it or use a shim.
    You should do that no matter what brake you use.
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  18. #18
    Master of the Face Plant
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    Done, I used a standard steel mount that I ordered online for $5.95. I bolted it to my brake and then cut it down leaving some extra material to miter out by hand. I shaped it as closely as I could with a dremel and used the brake as a jig. I dropped in a little brass on both ends and then checked the alignment and it was just right. No rubbing when I spun the wheel. I then took the brake off and the wheel and brazed it in place along with the braces. I still have a little more work to do filling in some spots sanding and I need to braze on my cable guides and stops but I am pretty happy with my first attempt at brazing.
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  19. #19
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    Nice! Looks like it will do the trick!
    PAYASO 36er.....Live the Circus

  20. #20
    Master of the Face Plant
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    Done, with paint and I dropped in some extra brass around the bottom bracket welds just to smooth out the look.


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  21. #21
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    Quote Originally Posted by sandmangts View Post
    Done, with paint and I dropped in some extra brass around the bottom bracket welds just to smooth out the look.


    Very nice brazing.
    1982, 1983, 1984, 1985, 1986, 1992 Stumpjumpers. 1995 Waterford 1200, 1999 Waterford RSE, plus a garage full of steel frames.

  22. #22
    Master of the Face Plant
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    All finished. Hit the trails a few times and so far it is still in one piece.

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  23. #23
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    Cool;

    I like it. Killer style. Those bars are definitely dope!
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