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  1. #1
    Of the Nameless Rabble
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    Filling voids in bottom bracket shell

    I'll make a long story short.

    When removing the bottom bracket from my wife's bike so I could replace it, I found that the mechanic who had installed the BB (yes, a guy at a bike shop) had done unspeakable damage to the BB shell, apparently by use of some kind of mechanical and thermal forces to create the masterpiece that you see here.

    Filling voids in bottom bracket shell-bottombracketshellsantacruz.jpg

    I will face and chase the shell, and I will probably use spacer to make up for any appreciable loss of shell width in the process. However, I don't want to face too deepójust enough to allow a good fit for the cup. That probably means that I will need to fill at least one void in the shell to prevent water and grit from entering, although I might get lucky and have a nice shell to work with. Any ideas on a good material to use for filling a void?

    I was thinking of using bees wax because it is simple, malleable, sculptable, waterproof, removable, and it should bond well with aluminum. Any other ideas out there?

    Thank you.
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  3. #3
    Plays with tools
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    I wouldn't bother, no water is going to get through the threaded portion of your bottom bracket. It's going to go between the bearing and spindle or come from other places on your frame. I would only face the shell enough to get rid of the rough edge on the left side and even that's not 100% necessary. The gouges won't cause any issues with BB alignment as long as they are free of burrs.

  4. #4
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    I second customfab's take. I've seen worse and still got them to work without a lot of cosmetics.

  5. #5
    The Wiking
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    Quote Originally Posted by oberwil View Post
    I second customfab's take. I've seen worse and still got them to work without a lot of cosmetics.
    I beat up my own frame, when trying to dismantle a stuck/trashed bracket with a hammer (the plastic cups were stuck)

    I filed of some of the scuffs, so the the bb would align somewhat nicely... works fine!
    with speed, shall technique be conquered

    The streets are the sketchiest of trails.

  6. #6
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    I wouldn't worry about water infiltration, but all other things being equal I can't see how not having a flat/square surface to tighten the bearing cup against could be as good as having one. Nothing to lose sleep over if you can't access the tools but I'd sure as heck give it a quick facing if I could.

  7. #7
    Fat-tired Roadie
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    Re: Filling voids in bottom bracket shell

    Quote Originally Posted by customfab View Post
    I wouldn't bother, no water is going to get through the threaded portion of your bottom bracket. It's going to go between the bearing and spindle or come from other places on your frame. I would only face the shell enough to get rid of the rough edge on the left side and even that's not 100% necessary. The gouges won't cause any issues with BB alignment as long as they are free of burrs.
    Third. I think you'd need to lose a ton of that surface for it to be a real problem. Facing away things that are raised above the surface would be enough for me.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  8. #8
    The Wiking
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    Quote Originally Posted by J.B. Weld View Post
    I wouldn't worry about water infiltration, but all other things being equal I can't see how not having a flat/square surface to tighten the bearing cup against could be as good as having one. Nothing to lose sleep over if you can't access the tools but I'd sure as heck give it a quick facing if I could.
    But tolerances are qutiely tight? so facing the entire scuff, might remove too much material!
    with speed, shall technique be conquered

    The streets are the sketchiest of trails.

  9. #9
    Of the Nameless Rabble
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    Quote Originally Posted by AndrwSwitch View Post
    Facing away things that are raised above the surface would be enough for me.
    Agreed. This is pretty much the plan. I don't want to go crazy removing material. I just want to ensure nice parallel surfaces.

    Thanks to everyone here for the input!
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  10. #10
    Plays with tools
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    The thing to keep in mind is that the surface of your bottom bracket shell has clearly been faced once before. It doesn't get out of alignment due to riding, and the scarring that's taken place is of little concern. I'm normally the one recommending the best possible solution to a problem and if I didn't have the tools on hand to fix that, I wouldn't think twice about riding it as is.

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