Stuck like glue, extremely good glue

Peanutt
Peanutt Posts: 229
edited August 2012 in Workshop
Hi,

I think I may have a problem. Recently the thread on my square tapered crank arm stripped and would no long take a pedal, I needed to go out in a hurry so I removed it and used the crank arm and pedal from my MTB as a temporary measure. It looked ugly but did the job and since then the kind manufacturers of my original crank arm have replaced it free of charge, only thing is I can't get the damn MTB arm off.

I tried using my crank extractor, like I have done loads of times before, the threads were level and squared up and I tightened it as far as it would go, then it stripped the threads from the arm when I tried to remove it. I've soaked it in WD40 for a good 3 days and tried a forged C clamp, Inserted the holding nut loosely put the clamp behind the arm and the tightening rod mounted on the nut, broke the damn clamp in half.

Next I rode the bike for a good 10 miles, once again with the nut attached but loose to enable the arm to work free but not fall off, nothing.

I've officially run out of ideas, I would use a 3 arm puller but its a shimano crank arm and has bevelled edges so the arms won't have any purchase. And yes, I've whacked it with a rubber mallet, many times.

Any ideas would be greatly appreciated
No matter where you are, that's where you've been

Comments

  • davem399
    davem399 Posts: 269
    I had a similar problem with a Campag left hand crank where the thread for the extractor was stripped.

    I used a automobile track rod end splitter I had in the shed. It is a forked, tapered wedge where the two parts of the wedge went either side of the bottom bracket taper, between the face of the bottom bracket and the back face of the crank. I then gave the the splitter a couple of sharp blows to drive it between the frame and crank and this was enough to release it from the taper.
  • jermas
    jermas Posts: 484
    Maybe try a blow torch on the crank arm. The alloy should expand more than the steel taper. Since the threads are already stripped it's ready for the recycle bin anyway.
    Good luck.
  • keef66
    keef66 Posts: 13,123
    +1 for the blowlamp suggestion.

    Is it possible you left the washer in there before you screwed in the crank extractor? That's what I did on the one occasion I stripped a crank. Pathological about it now
  • edhornby
    edhornby Posts: 1,741
    boil the kettle, pour over, ride the bike again with the loosened nut, uphill in as high a gear that you can rotate for maximum effect
    "I get paid to make other people suffer on my wheel, how good is that"
    --Jens Voight
  • term1te
    term1te Posts: 1,462
    I've taken this approach too, worked a treat in a similar situation. Make sure you have a metal face on the bottom bracket, if is is plastic, or worse plastic in a carbon frame, I'd think twice. I got the splitter for about £5 from Halfords, but that was about 10 years ago.

    DaveM399 wrote:
    I had a similar problem with a Campag left hand crank where the thread for the extractor was stripped.

    I used a automobile track rod end splitter I had in the shed. It is a forked, tapered wedge where the two parts of the wedge went either side of the bottom bracket taper, between the face of the bottom bracket and the back face of the crank. I then gave the the splitter a couple of sharp blows to drive it between the frame and crank and this was enough to release it from the taper.
  • Monty Dog
    Monty Dog Posts: 20,614
    Yup, also try hot-air blowgun as long as there's no plastic nearby (don't do this near carbon) - if that doesn't work, then fork-type, balljoint splitter will do it - you LBS may have one
    Make mine an Italian, with Campagnolo on the side..
  • Peanutt
    Peanutt Posts: 229
    Thanx guys,

    Definitely going to try the heat/expansion method, then if all else fails the ball joint splitter. Can't for the life of me imagine how is got that stuck, I know I did it up tight but geez I'm not that strong!!
    No matter where you are, that's where you've been
  • Peanutt
    Peanutt Posts: 229
    Just had a thought, I'm not mechanical so don't know a lot about these things, i understand that heating the alloy arm up will make it expand at a faster rate than the steel spindle but surely wouldn't it expand in all directions making the hole smaller and the arm even tighter as well??
    No matter where you are, that's where you've been
  • keef66
    keef66 Posts: 13,123
    No, trust me it will expand in a useful way.
  • mattcroad
    mattcroad Posts: 189
    And if all else fails pull out the hacksaw, cut a wdge out, rubber mallet, job done.

    10 mins max as the alloy is quite soft
    There is a rule for that
    FCN 4 2009 Trek 1.5
    FCN 11 2007 Apollo XC.26s
  • Peanutt
    Peanutt Posts: 229
    It's off.

    Tried everything, hot water, heat gun, 8 mile uphill ride, rubber mallets, pullers, prayer

    In the end I had to cut into it down to the axle, stamped on it a few times and it's finally off. Just need to find a left crank arm for my mtb now.
    No matter where you are, that's where you've been