Bottom Bracket for Stripped Threads

mabrum
mabrum Posts: 211
edited March 2008 in Workshop
A friend had a LBS fit a YST cartridge unit intended for the purpose in his stripped shell. It persistently loosens, which may be due to the shell ends not being chamfered to match the taper on the cartridge. Sheldon Brown says the chamfering is essential. However the LBS that I trust most says that these BBs loosen whether chamfered or not, although they do not possess the (expensive) chamfering tool which may influence their opinion. They say that it's new frame time.

Does anyone know if these things do work with the chamfering, and know of a shop in the Southampton area which has the tool?

I am aware of alternatives like rethreading for an Italian BB or cutting and rewelding the shell, but the frame is probably not worth the expense.

Mark

Comments

  • maddog 2
    maddog 2 Posts: 8,114
    mavic used to do a square taper bb which used lockrings to hold it in place, rather than the BB shell threads.

    not sure if you can still get them but they work okay. I used one on a go-kart I built (where the threads wre the wrong way round)
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • redvee
    redvee Posts: 11,922
    In the past I've had a frame reamed and sleeved when the BB threads have died, from memory £20 @ Argos, not the catalogue people.
    I've added a signature to prove it is still possible.
  • nicklouse
    nicklouse Posts: 50,675
    redvee wrote:
    In the past I've had a frame reamed and sleeved when the BB threads have died, from memory £20 @ Argos, not the catalogue people.
    http://www.argoscycles.co.uk/
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • mabrum
    mabrum Posts: 211
    Thanks for the ideas. The Mavic was a good product according to the LBS and they have tried and failed to source them over several years. Sleeving by Argos is now £65, plus stripping the frame and shipping it - it's probably a better idea to rebuild on to a new frame. Getting the YST BB to work with chamfering would be a much cheaper option if its possible.

    Mark
  • notsoracy rich
    notsoracy rich Posts: 229
    I had the Mavic BB fitted a few years ago-the shell needs to be chamfered because the lock rings have a taper,which is probably there to centralise the BB and ,if you think about it, is the only thing that stops the BB cartridge rocking up and down in the shell.
    If the YST BB works on the same principle that would explain why it works its way loose if the shell hasn't been chamfered.

    If it was my frame and I couldn't find a bike shop or local engineering shop to cut this precision chamfer, before throwing the frame away I would have a go with a half round file-no it wouldn't be precise , but it might be enough to get it to work. A bit of loctite may help as well.

    It shouldn't make it any worse, but if it did the frame was no use anyway, so a win/win situation!

    Hope this helps,
    Rich.

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