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  1. #1
    Senior Member xiaoman1's Avatar
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    going it alone..rear drop-out repair

    Hello,
    I posted a while back about needing a rear drop-out replaced .... to make a long story short the person that was going to help me did not come through.
    the old drop out has been removed and the new one shaped and is ready to put put back in place.
    My question are:
    1. What type of material would you recommend to put the drop into the rear stays....silver , brass or?
    2. can I use and oxy-acetylene torch or is there some other method.
    3. Any good videos out there that any of "you" have made
    Thanks for the help....
    Regards, Ben
    Paramount, Mondia, Px-10, Moto

  2. #2
    Andrew R Stewart Andrew R Stewart's Avatar
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    Without our finding your old post we will not know the issues involved. Andy

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    Randomhead
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    The other thread didn't really have any info either. Is there chrome involved? You said it was SL, is it vintage SL?

    Brazing dropouts requires a bit of faith. The first trick is to heat the dropout and not overheat the tube. The second trick is to get the filler to flow into the tube and not around the outside. This is done by making sure the dropout remains hot. And as always, make sure everything is really clean. I have used fillet pro silver on stainless dropouts, but there is no reason not to use brass (lfb) on a steel dropout. I think that for most beginners, even a fillet building silver is going to be harder than using brass for this application. And it's certainly a lot more money.

  4. #4
    Senior Member xiaoman1's Avatar
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    Quote Originally Posted by unterhausen View Post
    The other thread didn't really have any info either. Is there chrome involved? You said it was SL, is it vintage SL?

    Brazing dropouts requires a bit of faith. The first trick is to heat the dropout and not overheat the tube. The second trick is to get the filler to flow into the tube and not around the outside. This is done by making sure the dropout remains hot. And as always, make sure everything is really clean. I have used fillet pro silver on stainless dropouts, but there is no reason not to use brass (lfb) on a steel dropout. I think that for most beginners, even a fillet building silver is going to be harder than using brass for this application. And it's certainly a lot more money.
    Thanks for the response,
    Gios super with no chrome on the stays campy drops 73 vintage/sl tubing.
    My plan is to let gravity be my friend to get the the flow into the tubes. you mention brass, do I take it to mean brazing....is there a particular one/s that you would recommend?
    I also take it that I should just use enough to get a good flow but not a lot of build up, correct?
    I also plan to heat the drop out and go lightly on the stays....testing for right temp for flow into the stays etc.
    any other tips?
    Regards, Ben
    Last edited by xiaoman1; 09-22-15 at 08:28 AM.
    Paramount, Mondia, Px-10, Moto

  5. #5
    Randomhead
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    no, you want to fill the stay really well. I do mean brazing. I really like the LFB from Cycle Design or Henry James. The stuff you get at your local welding shop is usually horrible to work with. Sometimes, if you're lucky, they will carry Gasflux LFB, but it's more likely that they carry the generic

    You also want to use flux from one of those companies. I suggest you find some 1/4" thick scrap metal to practice on.

  6. #6
    Old fart JohnDThompson's Avatar
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    Quote Originally Posted by xiaoman1 View Post
    1. What type of material would you recommend to put the drop into the rear stays....silver , brass or?
    Brass; more specifically, low fuming bronze, available at any decent welding supply store. Get a good flux while you're at it. My favorite is GasFlux Type B paste.

    2. can I use and oxy-acetylene torch or is there some other method.
    Oxy-acetylene or oxy-propane will work. You will need oxygen; fuel/air torches simply won't get hot enough.

    When you place the dropout, take care to ensure that the slot is parallel with the slot in the other dropout, otherwise you'll have wheel alignment problems. A piece of steel plate or an unwarped board through both dropout slots works well for this. Make sure the slots in the stay are tight enough that the dropout stays in alignment after you remove the plate or board prior to brazing. Keep most of the heat on the dropout until it is up to temperature (the flux turns clear and glassy; the dropout glows cherry red), then quickly heat the stay end and add the brass. Use the heat to pull the brass into the stay. If you position the stay vertically with the dropout on top, gravity will help.
    Last edited by JohnDThompson; 09-22-15 at 10:39 AM.

  7. #7
    Senior Member xiaoman1's Avatar
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    Quote Originally Posted by JohnDThompson View Post
    Brass; more specifically, low fuming bronze, available at any decent welding supply store. Get a good flux while you're at it. My favorite is GasFlux Type B paste.



    Oxy-acetylene or oxy-propane will work. You will need oxygen; fuel/air torches simply won't get hot enough.

    When you place the dropout, take care to ensure that the slot is parallel with the slot in the other dropout, otherwise you'll have wheel alignment problems. A piece of steel plate or an unwarped board through both dropout slots works well for this. Make sure the slots in the stay are tight enough that the dropout stays in alignment after you remove the plate or board prior to brazing. Keep most of the heat on the dropout until it is up to temperature (the flux turns clear and glassy; the dropout glows cherry red), then quickly heat the stay end and add the brass. Use the heat to pull the brass into the stay. If you position the stay vertically with the dropout on top, gravity will help.
    John,
    Thanks for the reply, I was planning on using a threaded rod with nuts and washers on each end to align the drops...would you recommend taking a measurement at the leading edge of the BB to get the rear most edge of the drop in place (parallel to the BB or?).
    Also in your message above you mentioned removing the steel plate is this for heat dissipation reasons? My thought with the rod was that I could maintain alignment with the non-drive side while working.
    Heat drop to red and then "heat" stays "just" enough to draw brazing material...not red ( no burning of the stays...clear flowing flux) just enough for flow, correct?
    If these questions sound a little out of place to the experts my apologies.
    I also take full responsibility for the work I am doing and am looking for advice not blame, so no worries and thanks for the help.
    Regards, Ben
    Paramount, Mondia, Px-10, Moto

  8. #8
    Randomhead
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    a good temperature for lfb to flow out requires the steel to be solidly into the red. You don't want to get it too orange.

  9. #9
    Old fart JohnDThompson's Avatar
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    Quote Originally Posted by xiaoman1 View Post
    I was planning on using a threaded rod with nuts and washers on each end to align the drops.
    A rod won't necessarily align the slots so they're parallel; that's why I suggested a plate or board, like this:



    I actually have a fixture for this; it also helps ensure that the stays come out equal in length:




    Also in your message above you mentioned removing the steel plate is this for heat dissipation reasons?
    More so it doesn't fall out and smash your foot while you're brazing. Or, if you're using a board, so it doesn't catch on fire.

  10. #10
    Senior Member xiaoman1's Avatar
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    Quote Originally Posted by JohnDThompson View Post
    A rod won't necessarily align the slots so they're parallel; that's why I suggested a plate or board, like this:



    I actually have a fixture for this; it also helps ensure that the stays come out equal in length:






    More so it doesn't fall out and smash your foot while you're brazing. Or, if you're using a board, so it doesn't catch on fire.

    John thanks for staying with me on this....Great advice and images, I hope not from learning from past experience .....
    I like the jig you made but for my purposes and one time effort maybe more that I am able to do. I am wondering if I could use the plate method you suggested and lightly clamp it to the rear stays on both sides, do you think the plate would cause the heat to dissipate to quickly and cause problems with the brazing or would you be worried about heat migration to the non drive side?
    Regards,Ben
    Paramount, Mondia, Px-10, Moto

  11. #11
    Old fart JohnDThompson's Avatar
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    Quote Originally Posted by xiaoman1 View Post
    I am wondering if I could use the plate method you suggested and lightly clamp it to the rear stays on both sides, do you think the plate would cause the heat to dissipate to quickly and cause problems with the brazing or would you be worried about heat migration to the non drive side?
    If you can find a way to secure it, it would probably be ok. It could be a significant heat-sink pulling heat away from the work area, but I doubt the opposite dropout would be affected.

  12. #12
    Senior Member xiaoman1's Avatar
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    Quote Originally Posted by JohnDThompson View Post
    If you can find a way to secure it, it would probably be ok. It could be a significant heat-sink pulling heat away from the work area, but I doubt the opposite dropout would be affected.
    John,
    Thanks for the advice will give an update when I finish.
    Regards, Ben
    Paramount, Mondia, Px-10, Moto

  13. #13
    Senior Member xiaoman1's Avatar
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    Quote Originally Posted by unterhausen View Post
    a good temperature for lfb to flow out requires the steel to be solidly into the red. You don't want to get it too orange.
    Thanks for the reply...I take it orange is after red, correct?
    Regards, Ben
    Paramount, Mondia, Px-10, Moto

  14. #14
    Randomhead
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    yes, orange is hotter than red

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    Hi everyone,
    i am new one, don't know really how things work out here, but my friend recomended to me that i shouls ask here for a help.
    Didn't want to open new thread, hopefully is okey if i just put this here.

    As you can see in a picture i got a problem with broken dropout. Bike is Scott Timber, about 20 year old.
    I got a guy, who is a welder and he said he would attempt to fix it so i came here just to ask if you got any tips how he should do it, on what to pay special attention?
    Any help would be very appeciated.

    IMG_20160309_105154.jpg
    1st step would be to clean it properly, of course

  16. #16
    Randomhead
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    that is going to be virtually impossible to weld, because it's brazed together now. Re-melting the brass will make the weld unreliable and unpleasant for the welder. Unfortunately, simply brazing that back together isn't likely to work for long. The only real fix for that is to replace the dropout

  17. #17
    Old fart JohnDThompson's Avatar
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    Agree, that's too close to the brazed joint to avoid contamination of a welded repair. Best fix is to pull out the old pieces and braze in a replacement dropout. But be sure that this will be cost effective: it's quite possible you could replace the entire frame for what this repair and subsequent repaint might cost.

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