Worn BB30 crank spindle

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  • Worn BB30 crank spindle
  • davros
    Member

    Doing my annual pf30 bearing change and noticed there is significant play between the spindle and drive side bearing, to the extent that I can rotate the whole bearing including inner race around the spindle. There is no play on the NDS of the spindle.

    New crank required? Can’t say I could notice the amount of play through the pedals before I disassembled it. But I’m guessing in the long run it will reduce bearing life and the play will get worse.

    Some bargain gx eagle cranks on crc so at least the timing is good…

    BearBack
    Member

    Different BB might fix it?
    Theres lots of difference between 24mm spindles So i imagine there’ll tolerance differences with 30mm too across brands.
    I have an almost loose 24mm spindle in a fancy ceramic BB. Takes just a tickle to slide the spindle through. Once it’s preloaded there’s no bother and spins with very little drag, but is definately running with the bearings.
    The BB that came with the cranks is interference fit, but it’s a real cheap BB so that went in the parts bin.

    davros
    Member

    Using wheels manufacturing threaded cups so they stay in the frame and I just change the bearings. There is the same amount of play with the old bearings and the new ones. At least in the disassembled state. I’ve not reassembled it all to check for play when preloaded.

    tjagain
    Member

    Can you see a wear mark or feel a ridge with your nail?

    IIRC different grades of bearings have tiny variations in internal and external diameter so you can have a sliding fit or an interference fit. You might just have got a setup with the wrong fit or have all the tolerances adding up the wrong way

    davros
    Member

    There is an obvious wear mark when running my finger over it. There is much less play with the bearing sat on the outside section of the spindle which makes me think it is worn.

    crank

    tjagain
    Member

    New crank then. You must have been running it with s seized bearing.

    davros
    Member

    I think the original sram unit had seized on one side when I replaced it so that would make sense.

    Thanks for the advice 👍

    globalti
    Member

    Bloody hell that must have been making a terrible racket for months and months; how on earth did you manage to ignore it? BB30 cranks do creak as the spindle flexes microscopically inside the inner races and you’ll begin to see blueing as evidence (black oil). You can cure the creaks by applying bearing fit compound to the insides of the inner races but you’ve allowed yours to go so far that it’s beyond salvage.

    davros
    Member

    The bike was second hand and I only used the original sram unit for a few months then found it was seized after it was resting over winter. Can’t recall it making a racket! Been using the threaded wheels mfg unit since and not had any seized bearings, just worn out. Guess the damage was done years ago when I first got the bike.

    New crank on the way 👍

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