Brake boss thread size

Discussion in 'Observed Trials Discussion' started by Justin.L, Oct 21, 2004.

  1. Justin.L

    Justin.L Guest

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    does anyone know what size the threads are on v brake bosses? thanks.
     

  2. Yurich

    Yurich New Member

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    if you mean the outside thread, which goes into the frame/fork, then there are all kinds of funky sizes that vary from manufacturer to manufacturer. best bet is to go to your LBS to match some up if you need replacements
     
  3. B1105

    B1105 New Member

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    yea my bad, the exterior threads depend on the manufacturere, i gave measurement of the inside thread
     
  4. RomanR

    RomanR DualDisc 26"

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    I'm guessing you're making some v adapters? Let us know how that works out.
     
  5. Justin.L

    Justin.L Guest

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    Sorry I meant type of thread. Like you know theres m4 and nc 10 etc. And yes i am makin adaptors.
     
  6. tomacropod

    tomacropod Rum Pig

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    I got some turned down a while ago, they started as m7 and finished as m4 (for guess what :)

    but my project didn't work out eventually, mounts worked but despite 2 boosters, the pure frame still couldn't stay stiff against the pressure of v-brakes :-(

    I still have those turned down posts if anyone wants them, you don't need anything else to make a v-brake adapter, just put the canti mounts right into your lower 4-bolt holes.

    - Joel
     
  7. unlimits

    unlimits New Member

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    Tomac, could you put a picture or some drawn of what you are talking about? or can i see it in any page or post? it's to make myself an idea...
     
  8. RomanR

    RomanR DualDisc 26"

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    Here's a link to a thread with some ideas for v-brake adapters. There you can see a brake stud like the one Tomac is talking about.

    https://www.observedtrials.net/vb/showthread.php?t=5589&highlight=brake+adapter

    For some frames, having the v brake boss going into the bottom 4-bolt holes will make the v brake sit too far up, and the pads will rub against the tire because you'll run out of adjustment space. But for some frames it works.
     
  9. Justin.L

    Justin.L Guest

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    Sorry, I wasnt being clear enough, i meant the part that actually threads into the frame.
     
  10. OTAdmin

    OTAdmin Administrator Staff Member

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    There are a lot of different sizes for those. Your best bet is to take it down to your LBS and see if they have something that can match it.
     
  11. Justin.L

    Justin.L Guest

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    I got the type. And after screaming, yelling, swearing and bleeding, i made the adaptors. they look like crap and i may post pics when i get off my arse. thanks guys.
     
  12. tomacropod

    tomacropod Rum Pig

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    yes I just turned down a standard mount as Agrade has done, but didn't make the sheet metal bit. I figured that the clamping force of a v-brake onto the mount was more than enough to hold it in place against spring tension force, and that the little hole wasn't at all necessary. I was right too !

    Roman's right about the mount being a little low. I used old LX brakes (no parallel push, with the big square springs yo !) which had enough up/down sliding adjustment for my koolstop pads. Although having the pad that much closer to the pivot did increase the flex. I think the woodman ones could work fine if they didn't put the mount so far inboard. This makes it useless for any trials rims (or anything over 28mm or so) by the looks of it.

    After my little foray I just decided to give up and use whatever brakes the frame was designed for, the maggies work much better than the bodged Vs. When I get my BT though we'll be set Brett.

    "If life's a bitch then death's a slut, cos death comes for everyone, and when it's your turn you're fucked"

    - Joel