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Severely seized square-taper crank

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Severely seized square-taper crank

Old 06-26-12, 02:15 PM
  #1  
Airburst
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Severely seized square-taper crank

I'm building up an old frame as a singlespeed, and I've got a junk bike with an old Sugino crankset I want to use. The only problem is that the right-hand crank is completely seized onto the bottom bracket spindle. I've torqued the heck out of a crank puller on it, and I'm sure the puller is pushing the end of the spindle not on some kind of washer in the crank, but it won't budge. The left-hand crank came off pretty easily, but I'm at my wits' end with the right-hand one. I could work out some way to torque the crank puller harder, but I'm worried I'll strip the puller threads out of the crank. Any suggestions? Penetrating spray? Heat?
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Old 06-26-12, 02:27 PM
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How hard is hard? I have had to put a cheater pipe on one crank that was really stuck on there. I was very worried I was going to strip it but it didn't strip. At that point, if it started to strip, I was going to put a ball joint fork inbetwen the crank and the BB and give it a couple of good smacks with a steel hammer while the crank puller was still on there.

I didn't have to resort to that though, the crank arm finally popped off.
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Old 06-26-12, 02:29 PM
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If you are SURE there isn't a washer in there (you looked inside and can plainly see the square-taper BB end inside without anything in the way) then it should come off.

Check to be sure you have the right crank remover or that it is set up correctly and you don't have the wrong end-piece on. Some crank pullers have two different removable ends that pivot. If you have the bigger end (used for ISIS or Octolink cranks) on the crank puller it isn't going to be pressing on the BB and instead on the inside of the crank arm -just like if you had a washer in there. The end of the crank puller should have a pushing-end that is no larger than the diameter of the BB spindle. Make sure you didn't break something off or leave a piece behind in the other crank when you took it off.

Also, lubricating the threads within your crank-puller tool helps a lot too by reducing the internal friction. Regular grease works very well here. Lubing the threads of this type of tool is a regular maintenance chore that should be performed every once in a while to ensure they don't bind up.

If everything is lining up and fitting correctly and you have so much tension on the puller threads that you are afraid your are going to strip them then a give the crank a few bops with a big rubber mallet. You aren't trying to "hit" the crank off but simply add in some high-frequency vibrations into the joint while the tool is loading the pieces with pressure. A light and steady tap-tap-tap will get the metal vibrating and this sometimes help get things moving. You can also help things along by spraying in some high-quality penetrating oil designed for seized things like this. There is a product called "freeze-off" that works pretty well in these types of situations.
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Old 06-26-12, 03:56 PM
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You can carefully apply heat with a propane torch to the crank at the bb spindle. The crank arm is aluminum and the spindle is steel. Aluminum will expand faster than steel and the crank arm will loosen up. There is a risk that the threads where the puller is engaged will also expand and this could cause the puller to strip the threads. Also you will have to be careful not to let the torch melt any plastic and such that might be in the area.
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Old 06-26-12, 05:28 PM
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Lay the bike on its left side and fill the spindle cavity with penetrating oil. (the real stuff, not WD-40)
Let it sit a couple hours.
Tap lightly with a wrench to "vibrate" things every 15-30 minutes while sitting.
The crank should "jump off"!
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Old 06-26-12, 06:16 PM
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In cases like these, I use a motorcycle tyre-iron. Wedge it in between the crankarm & fixed-cup with the tip of the iron aimed at the crankarm. Pry towards the seat-tube and >POP< off it goes in 2-3 seconds.

Of course, depends upon how much exposed spindle you have between the crankarm & fixed-cup. With larger clearances, I've used a pickle-fork, used to separate automotive A-arms from ball-joints. Both methods causes minimal damage to crankarm and it can be re-used if you want.
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Old 06-26-12, 09:36 PM
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Buy a set of Jacobs Chuck removal wedges($10), use it like DannoXYZ suggests for the tire-iron " Wedge it in between the crankarm & fixed-cup". Works great, no damage. BTW, WD-40 is one of the least effective penetrating fluids, it is more of a water dispersing agent. PB blaster is much better, and the best is a home brew of 50% acetone and 50% transmission fluid.

Brian

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Old 06-26-12, 10:00 PM
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Originally Posted by calstar View Post
Buy a set of Jacobs Chuck removal wedges($10), use it like DannoXYZ suggests for the tire-iron " Wedge it in between the crankarm & fixed-cup". Works great, no damage. BTW, WD-40 is one of the least effective penetrating fluids, it is more of a water dispersing agent. PB blaster is much better, and the best is a home brew of 50% acetone and 50% transmission fluid.

Brian

Great idea, the acetone and TF, will have to give it a try.
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Old 06-26-12, 10:18 PM
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Before you go to the extremes, visit an LBS that has a bonafide version of the Campagnolo crank extractor - with the floating press head. Try that first.

Not all tools are the same...I can stick a Park in, no luck, stick in the same design from Campy - off it comes.

=8-)
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Old 06-26-12, 10:43 PM
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I had this happen once. I used a pickle fork (looks like a large tuning fork the tapers out) that I picked up from Napa (for about $8) to remove the crank. I just used the fork and worked my way around the crank (putting the fork between the bottom bracket and crank) and kept hitting it with a hammer until it popped up. It still took awhile and a lot of force to get that crank off. I would try the penetrating oil first as the pickle fork option seemed to be a little harsh. When I did it, I didn't end up marring the crank (or bb) - but, it still seemed a bit like a severe operation.
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Old 06-27-12, 03:45 AM
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Originally Posted by anixi View Post
Great idea, the acetone and TF, will have to give it a try.
Kroil is meant to be the good oil, but I hear the 50/50 acetone/ATF mix is better again.
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Old 06-27-12, 07:40 AM
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Old 06-27-12, 07:47 AM
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Originally Posted by Airburst View Post
The left-hand crank came off pretty easily, but I'm at my wits' end with the right-hand one. I could work out some way to torque the crank puller harder, but I'm worried I'll strip the puller threads out of the crank. Any suggestions? Penetrating spray? Heat?
If the crank remover is fully engaged to the bottom of the threads, there's plenty of engagement and stripping isn't very likely (though possible). I've had crank removers break before stripping threads. Use a longer wrench, and steady pressure until something gives. I know you're concerned about stripping the crank, but there's not much to lose here, since it's already worthless if it won't come off.

As an alternative, you can use a pair of Jacobs chuck removal wedges behind the crank to push, rather than pull it off the spindle. The wedges are fairly cheap (about $10.00 or less) and 100% successful for this job.
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