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Removing cranks

Discussion in 'Bicycle Mechanics and Repairs' started by Night Train, 8 Jun 2008.

  1. Night Train

    Night Train Guest

    How can I remove aluminium cranks from a steel bottom bracket shaft when it is feels well and truely welded together?
    I have tried bashing it with No1 bike tuning tool (big lump hammer), using a gear puller (bent chain rings into a taco), gear puller and No1 bike tuning tool (loads of noise, no movement).

    Both bits are scrap anyway but I want the frame member for mocking up, preferably with a bottom bracket still in it. The frame is aluminium too.

    Thank you.
     
  2. yenrod

    yenrod Guest

    Night - I think the next stage is to either get the blow-torch on it (aiming for the contact area) OR a BIG SAW - messy but will do the trick...

    Id go for the saw: difficult as hell but will get it off!

    I had to saw a crank off once (c.set side) and you realise how much alu' is packed into a crank !
     
  3. Steve Austin

    Steve Austin The Marmalade Kid

    Location:
    Mlehworld
    Put the bolt back on and half tighten it. take your bike and hop off a few kerbs, it will come undone
     
  4. hubgearfreak

    hubgearfreak Über Member

    i might be missing something, did your list of things include crank extractor?
     
  5. fossyant

    fossyant Ride It Like You Stole It!

    Location:
    South Manchester
    Crank extractor attached to a dirty great big spanner !!!!
     
  6. OP
    OP
    Night Train

    Night Train Guest

    It's one of the half dead bikes I picked up yesterday that I am stripping.

    Right, lots of heat, the puller tightened up and copious bashing got the left crank off. Didin't work with the right crank though.
    Heat, puller, loads of bashing and the taco chain rings broke loose but the crank didn't.
    Saw the chain rings off and start again.
    Heat, puller, bashing and still no joy.
    Drilled through the end of the crank so only three sides of the square and a sliver of aluminium still touching.
    Heat, puller, loads more bashing and eventually it came off.
     
  7. Sounds extreme NT - an extractor with a bit of tubing over the top (as a last resort) Blowtorch, machine gun, hacksaw?:rolleyes: - extreme talents :biggrin:) I couldn't bring myself to do that :wacko:

    Well done if it worked for you. :smile:
     
  8. Dayvo

    Dayvo Just passin' through

  9. OP
    OP
    Night Train

    Night Train Guest

    It was well and truely corroded on. I don't think there was any chance of it coming off cleanly. The chain that was on it is just rust that sort of moves a bit if it is forced.

    Still I now have a bit of aluminium frame to set up the back end of my recumbent mock up.
     
  10. Danny

    Danny Legendary Member

    Location:
    York
    I had this problem once, and took my bike to my LBS. They got the crank off by pouring boiling water from a kettle all over it. Apparently it makes the metal expand enough to work the crank loose.
     
  11. OP
    OP
    Night Train

    Night Train Guest

    I had a propane blow torch on it, way over 100c. Melted the plastic bushings on the suspension pivot nearby.
    The only thing I've come across that tight has been leaf spring bolts on my old Land Rover. Had to burn out the rubber bush to get them out.
    I'm glad it was only scrap.
     
  12. Yorkshireman

    Yorkshireman New Member

    When time is of the essence (and threads are 'bare'), one has to show who's in charge
    2008_0429TREK7000003.jpg
    One must be prepared to be firm (very firm), and brook no nonsense
    2008_0429TREK7000004.jpg
    :biggrin:
     
  13. Yorkshireman

    Yorkshireman New Member

    When time is of the essence (and threads are 'bare'), one has to show who's in charge
    2008_0429TREK7000003.jpg
    One must be prepared to be firm (very firm), and brook no nonsense
    2008_0429TREK7000004.jpg
    :biggrin:
     
  14. Steve Austin

    Steve Austin The Marmalade Kid

    Location:
    Mlehworld
    Grins approvingly ;)

    Saw Colin?
     
  15. Yorkshireman

    Yorkshireman New Member

    Saw red:biggrin:. - I'd arranged to go on a ride with some visitors the next day (something I rarely do - her indoors reckons I'm a miserable old bugger:o)). The old crankset was put on by the LBS (due to faulty BB bearing) when the bike was only six weeks old, nine years ago. I've never done a cotterless crank job before (but I've seen plenty done at the LBS when 'passing the time of day with the lads'), so I had a new crankset, new BB bearing and new crank extractor tool. Took the plastic bolt covers off ... No (or hardly any) sound thread to see in there. Gave it a try ... the extractor bolt simply pushed itself back out. Bike on its side (with block of wood under opposite crank for support), hacksaw down as far as the bearing shaft, drill a series of small holes from there to the edge of the crank. Sharp stone chisel and lump hammer, two or three good taps ... Called in the LBS a couple of days later and told the manager (the only original member of staff) ... My how we laughed ;).