help removing crank from bottom bracket spindle

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  • help removing crank from bottom bracket spindle
  • theflatboy
    Member

    following on from my fascinating “what bottom bracket” thread from earlier, i have now encountered an obstacle.

    I have had the chance to remove the old BB, but with a slight problem: the extractor threads in the left crank are slightly damaged (i don’t know how – they were not new and i have not noticed this before) on the outside, so my crank extractor won’t engage. there is still about 90% of the thread that would be “good”.

    i now have a removed BB but with one crank still on the spindle. so i may yet be getting a new chainset to go with the new bottom bracket!

    any suggestions on how to remove said crank would be much appreciated!

    Premier Icon cynic-al
    Subscriber

    vice or similar and hammer if the extractor won’t engage (I’ve never done this but people say it works).

    Some lbs have oversize thread cutters/removeers (stein) for this situation if it’s worth the expense/

    theflatboy
    Member

    i have tried the hammer technique but sadly am lacking a bench and vice so it proved fairly unsuccessful – i may need to persevere with it but the baby is now asleep so can’t right now!

    (oh and they’re not really worth the expense, though i would much rather avoid having to fork out cash as i’m very skint right now!)

    cyclistm
    Member

    I missed the earlie thread, are they square taper?

    Have you def removed all washers?

    I have used a hammer in the past but it doesn’t do thet crank much good.

    Try riding around on the bike with the bolts undone

    theflatboy
    Member

    1. no, isis.

    2. yes definitely – the problem is there is visible damage to the thread going a mm or two in, meaning the extractor won’t bite at all to do its work.

    3. i would rather preserve the crank, the BB’s for the bin anyway.

    4. no can do – BB is no longer in the frame and is extra wrecked now from my efforts to detach it from crank!

    Premier Icon jamj1974
    Subscriber

    Hold BB in vice and buy a new extractor (They often bite better…). Other than that an option I have seen used before is the installation of new self-extracting bolts (Again they often bite better.), and use an 8mm key to remove.

    Have you tried lubricating the thread?

    brakes
    Member

    try rechasing the threads with a bradall/ stanley knife/ similar pointy but of metal so the tool will engage.
    or try a better BB extractor? Park Tools ones seems to extract cranks that have had their threads pulled out by lesser extractors.
    I can lend you one if you like.

    theflatboy
    Member

    ok, good tips. and cheers for the offer, may take you up on it depending how i get on!

    Premier Icon cynic-al
    Subscriber

    What brakes said.

    Otherwise if using the hammer, brace the crank on a kerb or similar – you need something that doesn’t move like wooden or vinyl flooring, workbenches etc.

    project
    Member

    Apply heat to the crank arm with a hot air gun or better still, witha blow torch, best doen outside, heating aluminium allow makes a smell and sometimes fumes.

    ALUMINIUM ALLOYS EXPAND FASTER THAN STEEL

    REMEMBER IT WILL BE VERY HOT, SO USE THICK LEATHER GLOVES OR A HAMMER TO RELEASE THE CRANK.

    Not faced the above, but have used a length of scaffolding pole and another occasion the good old angle grinder.

    theflatboy
    Member

    i’ve had another look, tried a bit of thread chasing with stanley knife. no luck so far… very annoying – this is becoming a costlier and costlier task!

    theflatboy
    Member

    well i concluded the crank is dead, and as there was a virtually like for like brand new chainset and bottom bracket on ebay for very cheap i bit the bullet and went for that instead!

    anyone want a right hand truvativ elita crank in used but good condition?! 😆

    cheers for tips all, anyway. 🙂

Viewing 13 posts - 1 through 13 (of 13 total)

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