Advertise on Bikeforums.net



User Tag List

Results 1 to 10 of 10
  1. #1
    Junior Member GirchyGirchy's Avatar
    Join Date
    Apr 2006
    Location
    Central Indiana
    Posts
    7
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Ovalized BB shell - any way to fix?

    Hi,

    I have an interesting problem and was hoping for some suggestions. I was given a '77 Raleigh Super Course frameset a while back and rode it as is for a few years. Its paint wasn't in great shape so this past week I finally got around to having it repainted.

    This afternoon I was beginning to attach some of the decals to the frame when I thought I'd mess around with the bottom bracket to make sure it would go in cleanly. Tried one, didn't want to go in. Tried another, same thing. Checked thread size with the BB it came with, and all three matched. So I pulled it down to look, and the whole BB is ovalized.

    I'm not sure if it fell or what, but that's what I'm guessing. Preliminary investigations point to the painter - I have a couple which show the BB after sandblasting and before paint, and it appears fine at that point. It's worse on the non-drive side but affects the drive side as well.

    Either way, is there any hope of fixing this? Perhaps try to push it back out using some wood and clamps on each side of the indentation, or pull the flat spot out (perhaps by using two rods to press on the inner sides of the shell while pulling them apart)?

    Any thoughts would be appreciated!

    Brian




  2. #2
    meech151
    Join Date
    Apr 2009
    Location
    Mountain Home, AR
    My Bikes
    MEECH road & cross bike
    Posts
    206
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I'm not an expert on frame repair so I am curious to hear some ideas from others who are more experienced but the first thing I would try is to take it to a shop and see if they can get a BB thread tap started and possibly recut the threads. This would save the new paint if it works. Not sure how out of round it is but it looks like it took a decent hit. This is the exact kind of thing I worry about every time I leave a frame with someone else. I am lucky that the guy who paints my frames takes extremely good care but after seeing this I think I will start inserting a BB in before I take it because sooner or later something is bound to happen, if nothing else it keeps the threads clean.

  3. #3
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,484
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    it looks bad, but I'm nearly positive that you could chase that an have it work. You might want to use locktite. Should be faced after paint anyway

  4. #4
    Junior Member GirchyGirchy's Avatar
    Join Date
    Apr 2006
    Location
    Central Indiana
    Posts
    7
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by meech151 View Post
    I am lucky that the guy who paints my frames takes extremely good care but after seeing this I think I will start inserting a BB in before I take it because sooner or later something is bound to happen, if nothing else it keeps the threads clean.
    You know, I almost did this, since I have a few old ones sitting around. Hmph.

    The threads are in ok shape - I'm worried if I chase it, it'll mess them up and go too deep on the "narrower" sides of the oval, and it would still be too loose on the other two sides.

  5. #5
    Senior Member ftwelder's Avatar
    Join Date
    Apr 2010
    Location
    vermont
    My Bikes
    Many
    Posts
    3,093
    Mentioned
    7 Post(s)
    Tagged
    1 Thread(s)
    You should pry it round from the inside first, before attempting to tap it. install a steel cup in the good side and get a 1-1/4" steel bar a couple of feet long and insert it in the cup to protect the threads of the good side and apply some small force to the dent. I personally would find the bar already attached to something and use the frame for leverage.

  6. #6
    Junior Member GirchyGirchy's Avatar
    Join Date
    Apr 2006
    Location
    Central Indiana
    Posts
    7
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Even the "good side" isn't all that great, so I may have to get creative with it first. But I can try to thread in one of the original BB's cups. They're the old adjustable cup 'n cone type so the cups have a hole in the middle, perfect for a bar to run through. I can wrap some tape around a breaker bar or something to protect the bad side. Thanks for the tip!

  7. #7
    Banned
    Join Date
    Aug 2005
    Posts
    5,117
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Get three wedges, that add up to parallel, and beat the centre wedge in to stretch out the tube. There are also sets for expanding muffler tubes. I played around with them at one point in order to come up with something to hold Eccentric BBs. You would need to put something in to protect the steel. You might also need to put a shim in to draw it oversize in one direction.

    http://compare.ebay.com/spid/4351987...mTypes&var=srf

  8. #8
    Junior Member GirchyGirchy's Avatar
    Join Date
    Apr 2006
    Location
    Central Indiana
    Posts
    7
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Peterpan1 View Post
    Get three wedges, that add up to parallel, and beat the centre wedge in to stretch out the tube. There are also sets for expanding muffler tubes. I played around with them at one point in order to come up with something to hold Eccentric BBs. You would need to put something in to protect the steel. You might also need to put a shim in to draw it oversize in one direction.
    Ooh, I like the wedge idea. I may be able to make some at work out of aluminum, to protect the steel - two right angle triangles to sit against the inner BB and an isosceles one to drive between them. I should be able to curve the sides of the right angle ones so that they fit the curvature of the BB. Thanks!

  9. #9
    Banned
    Join Date
    Aug 2005
    Posts
    5,117
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The perfect wedges would have a little lip on the end to hang onto the face of the BB. That is basically what they call feathers for splitting boulders, so the power of the wedge can be impressive.

  10. #10
    Junior Member GirchyGirchy's Avatar
    Join Date
    Apr 2006
    Location
    Central Indiana
    Posts
    7
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I think I got the thing fixed well enough to use! I tried some wooden wedges first, and they didn't do much more than get stuck. I think they may have spread out the "good"/drive side just a tad, because I was finally able to get that one to thread in cleanly. I did this with the old Tange BB shell, stuck the axle in and used the hole in the shell as a brace, and hammered the axle into the bad side where it's pressed in. It pushed it back out just enough to let the non-drive side thread in relatively cleanly.

    Not sure if I want to take it back for another clearcoat after the decals go on - at least not without a BB threaded in! Thanks for all of the help, guys.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •