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BB shell threads worn

graemefergusongraemeferguson Posts: 5
edited July 2014 in MTB workshop & tech
I recently got an alloy frame and as part of my frame prep chased the threads in the bottom bracket, fitted a shimano bb to the specified torques. ( Think it was 40 nm on Drive side and 15Nm on non drive.) After a few moderate rides with some steep uphills I felt some play in the bottom bracket. The cartridge had worked its way loose and when I striped and inspected the bike the threads in the BB shell were worn down. The BB cartridge threads were fine. Does anyone have any idea if I can save this frame?


  • jonnym5jonnym5 Posts: 76
    Argos racing cycles can put a new threaded insert in but it's the cost involved in doing that. Had it done to two bikes in the shop recently and the repair was to a very good standard.

    Did you happen to put a 68mm BB in a 73mm shell?
  • jonnym5jonnym5 Posts: 76
    I've found them to be a bit censored in terms of longevity and some of them suggest the shell faces be cut out to match the angled surface of the BB.
  • ScareyJScareyJ Posts: 64
    edited July 2014
    Don't know if this will help or hinder, But in my student days I kept a knackered Motorbike (Alloy frame, all threads goosed) on the road with green thread lock. It's more of a gel than a liquid, meant for thread repair, I never had any problems with threads after that, took a bit more effort to remove parts, but just cleaned the threads and reapplied the thread lock, fastened finger tight, leave it for five mins to set a little, then torque up as normal.

    Might get you out of a bind

  • Thanks very much guys, I'll try the threadless BB first. If it doesn't work I might just buy the Italian cutting dies.
  • crakercraker Posts: 1,739
    I've been happily using a threadless BB happily for a year or so now.

    First time I fitted it it came loose after a few rides, so I chamfered the inside edges of the BB shell (I think you'll see there's a chamfer on the matching edges of the BB.) This can stop any vertical play in the system causing it to come loose; it's worked for me and wasn't a difficult job (hand drill with a small grinding wheel in).

    The BB I bought (ebay special) doesn't appear to be as good as the Shimano ones it replaces. Little bit of play after a year, still going though.
  • Cheers Cracker

    I'll give it a go.
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