Bicycle Mechanics - stripped head of crank bolt

My socket wrench wasn't enough to turn one of my crank bolts, so I put an 18" breaker bar on it. This only rounded the head off the crank bolt. What can I use to get it out? I think my best option is one of those bolt extractors that screws into the head of the bolt ccw and can be turned to extract it. Hole has to be drilled into the head of the bolt.

If you couldn't break the bolt loose with an 18" breaker bar, it's unlikely that you'll succeed with an "easy-out." It'll break first, and then you are even worse off, because they're made of some darn hard steel. Been there, done that (although not with crank bolts).

I'm afraid your best solution at this point is to get a cobalt-steel 10mm drill bit and some cutting oil, lay the bike on its side, fill the crank-bolt cavity with cutting oil, drill the head right off the bolt, use a crank extractor to pull the crank, and see if you can lock onto the bolt with a Vise-Grip plier. This way you save your cranks, at least.

Good luck! :) And with the drilling, I'd suggest going at 500-1000RPM with quite a bit of pressure. Slower's better sometimes.

That's a good point. Guess I'll have to drill the head off.

Did you use a 12 point or 6 point socket?

Soak the bolt in WD40 or a good Penetrating oil. Let it stand for several hours then apply some heat to the bolt. (It doesn't have to be too hot.) Then soak it with penetrating oil again. Let it stand for awhile and then use a 6 point socket. Tap it on with a hammer if necessary. If it still won't loosen with that 18" Breaker bar, then drilling the cap off as mechBgon suggests is the next best solution. Good luck.

It was 6 point. I was going to take another crack at it after soaking it in penetrating oil. I'll try to heat it up too. I think I may have rounded it off too badly to get a grip on it again with a socket. I should have stopped when I saw that it was taking so much torque and not budging.

You might want to try heating the bolt up first with a torch. I have seen cases where someone used loctite red on a bolt and it would only come out with heat. Just dont get the bottom bracket so hot you cook the grease inside. Also dont use an acetalyne torch unless you are very carefull, it would be very easy to melt the cranks. I would try carefully heating it and using the reverse thread screw extractor, if that doesnt work, the comment about drilling it out and using a vise grips to remove the bolt is another good idea.

I know this will probably sound daft but are you certain you are turning the bolt the right way? It should be anti-clockwise for chainwheel side and clock-wise for other. In other words bolt should undo the opposite way to pedal action on both sides.

Its easy to forget in the heat of the moment, frankly I have never experienced a crank nut/bolt as hard as yours to release so its worth double checking

Originally posted by earleybird
I know this will probably sound daft but are you certain you are turning the bolt the right way? It should be anti-clockwise for chainwheel side and clock-wise for other. In other words bolt should undo the opposite way to pedal action on both sides.

Its easy to forget in the heat of the moment, frankly I have never experienced a crank nut/bolt as hard as yours to release so its worth double checking


Earleybird,
Are you sure? On my three Shimano bottom brackets, one old Italian thread bb, two new English thread, all crank bolts have normal threading - clockwise to tighten, counter-clockwise to loosen (right to tight, left to loose). The bb threads in the bb shell are different on the English threaded bbs but not the crank bolts.

To tell you the truth, though I do all my own bike work I would probably take something like this to a shop. Another thing to consider. Bottom brackets are cheap ($20-30), frames are not. Don't do something extreme or awkward that could wind up damaging the frame because of a slip or excess leverage.
FWIW,
Raymond

knobbymojo,

I've got a butane torch that should do the trick. I won't fire it up for long so that the crank and bottom bracket won't be damaged.

earleybird,

I believe they are both ccw. The one on the chain side is the one that is stuck and I've been trying to turn it ccw. The other side came out very easy and it was also ccw. Could it be that the chain side is cw and the other side is ccw? I don't think so since these are cotterless cranks with the square tapered attachment to the BB. There would be no advantage to making one bolt remove cw.

Well this is what happens when you go shooting your mouth off before putting your brain in gear.
I should have checked shouldn't I :o :o
I am sure you are both right JDP & RainmanP
I just remember last time I removed my cranks a couple of months ago I did try to remove one in the wrong direction ( brain fade)
I guess I reasoned that the pedal action should have the effect of tightening the axle bolts both sides which would suggest one side ( non chain side ) should be cw to undo and the chain side ccw .
:confused:
I will go right now and check my cranks Apologies in advance JDP for giving you advice before checking the facts.

Darn I hate this humility bit... its ....well its humbling:o

No problem. I've turned many bolts the wrong way, especially when I'm not facing the head. You have to remind yourself that everything is reversed. As soon as I saw how hard it was to turn the crank bolt, I had to double think my rotation and I wondered if it was cw to remove for some reason. Thanks for all the advice. I plan to work on it tonight since I'll be commuting by car tomorrow.

EB,
Don't think a thing about it! I have learned a lot about bike mechanics over the last couple of years, but there are many things that I get mixed up and confused about because there are so many different variables out there. The answers to so many questions become "Well, IF you have this... and IF you have that...and IF it's like this... and you know how to tell the difference, it MIGHT work. Luckily on my own bikes I feel confident just trying different combinations of things. The nice thing is that other than STI shifters and wheels, most other things are not that expensive.

I'm not good at much, but I am not too proud to admit my own ignorance. I've never done anything on my bike without reading how in 2 or 3 different books.
FWIW,
Raymond

Arghhh. Penetrating oil and heat didn't cut the mustard so I just left it as is for now. I'll have to drill out the head but there's no hurry since I'm not ready to change out the chain ring just yet.

Originally posted by RainmanP



Earleybird,
Are you sure? On my three Shimano bottom brackets, one old Italian thread bb, two new English thread, all crank bolts have normal threading - clockwise to tighten, counter-clockwise to loosen (right to tight, left to loose). The bb threads in the bb shell are different on the English threaded bbs but not the crank bolts.

Raymond

I'm with Raymond on this one. The crank bolts are normal direction - rigthtie tighty, lefty loosey.

I'm with Raymond on this one. The crank bolts are normal direction - rigthtie tighty, lefty loosey.


Cripes Mike how much humility do ya wanna see?

You wanna see a grown man cry???:D

Originally posted by earleybird


Cripes Mike how much humility do ya wanna see?

You wanna see a grown man cry???:D

Nah, sorry. I posted before seeing that the bolt direction thing had been figured out already.:rolleyes: Feeling silly now.

Originally posted by mike


Nah, sorry. I posted before seeing that the bolt direction thing had been figured out already.:rolleyes: Feeling silly now.

Not half as silly as I felt I can tell you!