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Need help removing rusted-on Profile crank

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  • Need help removing rusted-on Profile crank

    I need some suggestions/help in removing a rusted-on Profile crank arm. I have the crank arm removal tool and I have been beating on the thing with a hand-held sledge hammer and it will not budge.

    In conjunction with the regular hammerings, I have tried the following:

    1) soak in liquid penetrant
    2) soak in PB blaster
    3) soak in white vinegar (I am told it removes rust)
    4) Propane torch to heat the axle/arm junction
    5) Tried an automotive puller tool, but could not get a good grip

    I am thinking of cutting the crank arm off with a Dremel tool and a carbide wheel. I have done a test on a busted Profile crank arm, and the results look good. But I am unsure on how to proceed on where to cut. I think I may have to cut the bearing off first in order to get adequate room to cut the arm all along the vertical axis. Please see pics. (The pics make the rust look worse than it really is).

    Any suggestions are appreciated.
    Attached Files
    Buy a new Uni
    Cut the arm off
    More hammering/soaking/heat
    Do something else

  • #2
    A few things come to mine. You said you heated the axle/arm junction. Heat may help but you should only heat the thinner out side of the crank arm. The idea is that you heat the crank arm as much as possible while the axle remains as cold as possible. The temperature will make the crank arm larger and possibly loosen the crank arm.

    If you use heat or not it would help to rig up some solid support for the crank as close to the axle as possible. With a solid support the hammering would be much more effective. Lacking some solid support an other idea would be to add weight to the crank arm near the axle as possible. If you have to cut them off, welding a weight to the arm to make the hammering more effective may be easier.

    If you have to cut it off you should be able to turn your cutter 90. Then just grind away just to the spline. You may get by with grinding to one side or may need to grind two sides opposite of each.



    • #3

      If crank arms are easy enough to buy new, and you have tried the list of things above, I would remove the crank arm with an angle grinder if you have one.

      With the crank arm pointing down, very carefully grind a flat on the top face. As you get closer to the spindle spline, you will see the crank arm materiel turn blue. this will indicate that the material is very thin. Very carefully grind a little further. You should be able to then wiggle to crank arm, maybe put a pedal on it and press down with your foot. This should relieve the tension / clamping pressure around the spline. You should be able to pull the arm off.

      Good luck.


      • #4
        Before you cut it - last option, but it would work - I would try one last thing. It always works on 40yrs+ rusty bits on my old VW cars...

        Heat up the crank at the connection on the hub, pretty hot. Then put away the flame and spray the crank/hub with penetrating oil (or WD40 if you don't have anything else, but it's better to use something meant for seized metal). It will produce a lot of stincky white smoke (don't inhale!) and possibly some flames which you can just blow off. As it's still hot, tap it a bit with a hammer to induce some movement. The heating is not about having one part dilates more than the other (practically impossible since they're in contact), but the thermal shock from the spray will break the rust "glue". Then try the crank remover. It might take several attempts, but I've always had success with this method... on seized brake drums and other rusty parts.


        • #5
          Great point there. There is another option, which is to heat it up as suggested above, and get an old candle and rub that over the job / interface.

          I have found that the paraffin wax that candle is made of, will be wicked into the joint. If this doesn't work, grind off as suggested.


          • #6
            I have a similar problem on an Isis crank/hub, what I was thinking of is welding a nut onto the crank (concentric with the hub, ideally left hand thread), and using that as a stronger version of the "self extractor" type of crank removing tool that this type of crank usually comes with, possibly alongside heat. Might be worth a try before using the dremel.
            In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move. -Douglas Adams.


            • #7
              From the pictures it looks like you are due for a new Uni!
              If your not sore, your not ridin' long enough!


              • #8
                Thanks for all the suggestions. I managed to get the crank arm removed using pierrox's method of spraying penetrating oil (in my case PB blaster) into the crank/axle interface after heating only the outside of the crank arm with a propane torch using jimT's suggestion.

                Then after more hammering using the profile tool, the crank finally came off. I think one of the previous methods allowed the crank to break its grip.

                It's strange, but I don't see any rust on the axle where it had mated with the crank. It was just very very tight. I am going to be changing arms and lubricating the axle with anti-seize so hopefully I won't see this problem again.
                Last edited by unibabyguy; 2017-11-25, 01:57 AM.