Bottom bracket unscrewing

Discussion in 'Bicycle Mechanics and Repairs' started by mcshroom, 16 May 2010.

  1. mcshroom

    mcshroom Bionic Subsonic

    Location:
    Egremont, Cumbria
    Anyone ever met this one?

    My BB lock ring keeps unscrewing when I'm out on long runs. I've taken it off, cleaned the threads on the bb and frame and put back in with lithium grease but it still does it. Could do without it doing this when I go for my tour next month.

    I'm thinking about finding a less good grease for the threads, or using an anti-seize but they are a bit of a step in the dark and I don't want to get it stuck in there.

    Bikes a Claud Butler Hybrid with an alu frame and cartridge bb
     
  2. Gerry Attrick

    Gerry Attrick Lincolnshire Mountain Rescue Consultant

    You could try wrapping the part of the thread that the lock ring screws on to in PTFE tape before installing the ring. It acts as permanently pliable thread lock and also prevents seizing.
     
  3. OP
    OP
    mcshroom

    mcshroom Bionic Subsonic

    Location:
    Egremont, Cumbria
    Is that the tape plumbers use?

    Could be a plan.
     
  4. Gerry Attrick

    Gerry Attrick Lincolnshire Mountain Rescue Consultant

    Yep, that's the stuff. Get it in any DIY shop for next to nowt.
     
  5. Globalti

    Globalti Legendary Member

    You can get different strengths of locking compound. A good tool shop will advise.
     
  6. swee'pea99

    swee'pea99 Legendary Member

    Is this an Italian BB? They can be a bugger for unscrewing themselves. I only solved it with a big screwdriver and a hammer. If it's British, I'm baffled...they're supposed to tighten themselves as you go, not loosen.
     
  7. Crankarm

    Crankarm Guru

    Location:
    Nr Cambridge
     
  8. TheDoctor

    TheDoctor Resistance is futile! Moderator

    Location:
    Stevenage
    Well...it can't be an Italian BB in a British frame (or t'other way about) as one of the threads would be the wrong way round, so you'd never get it in.
    I'd Loctite it meself, but get advice. IIRC there's red (weakest), then blue, and finally green (never ever coming out).
     
  9. rustychisel

    rustychisel Well-Known Member

    Are you sure that a) the bottom bracket shell is adequately clean and faced (ie reasonably smooth and flush) and :thumbsup: most importantly, you're doing it up tight enough? The manufacturers spec for torque is really rather surprisingly high.
     
  10. OP
    OP
    mcshroom

    mcshroom Bionic Subsonic

    Location:
    Egremont, Cumbria
    Hi everyone thanks for all the tips.

    To update I cleaned everything off and wrapped some PTFE tape on the threads before re fitting. I also used an allen key with much greater leaverage (my bb tool is allen key driven).

    It's worked. I took it out for a 100km slog up some steep hills (Whinlatter pass) and it's still tight and happy. :laugh:

    Thanks
     
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