Bicycle Mechanics - holy crap, cottered cranks!!

ok, i have been trying to follow sheldon browns way of getting cottered cranks off. my pipe is a little short. now i have bent cotter pins. and the cranks havent moved a inch.

does any body have any advice before i go crazy?

You'll need to remove the cotter pins completely before you can really do anything with the cranks. Big hammer usually removes cotter-pins very well... you'll need new ones after that...

In really bad cases, I've actually drilled and tapped the cotter pins on the back side. Screw in a bolt and use a slide-hammer...

yeah, im trying to get thoose pins out. but all i have done is wacked at the pins with no luck. damaging them pretty bad.

maybe i need a bigger hammer...... or a saw....

No insult intended but are you hammering the correct end of the cotter? Did you back off the retaining nut but leave it threaded on enought to protect the threads? :)

none at all. haha. yes, im hamering the treaded end. i got a pipe used it to take the impact, and wacked away. and i left the nut to make a flater even surface to hit, and to save the bolt. but now i have bent bolt with a nut on it.

at this point, generally what i have found to work best is to cut the cotter flush at the crank, do the pipe/board bit, and resume hammering. if it mushrooms at this point, you're pretty much left with the drilling option.

Some kind of penetrating lube will do wonders... Pour it in from the nutted side, and repeat as necessary.

i should add using pliers of some sort to hold the punch will allow you to hammer without fear of losing fingernails.

Big hammers and banging away with brute force? What barbarians.

Press them out with nothing but a bench vise and a socket.
-Remove nut and washer.
-Apply a few drops of penetrating oil to the cotter bolt.
-Re-install the nut and washer so the top of the nut is flush with end of the cotter bolt.
-Select a socket in a size that fits over over the bolt head.
-Now arrange the cotter bolt and socket in open vise jaws so as the vise is closed it will press the cotter bolt head into the socket. These bolts are usually very stubborn and take considerable force to release. When they let go they reply with a dramatic CRACK, the sound of success.
-Remove from the vise and remove the nut and washer, then press the bolt out with your thumbs or at most a little tippity tip tap. It will drop into your palm in reusable condition.

I have never had a failure using this foolproof method.

Big hammers and banging away with brute force? What barbarians.

Press them out with nothing but a bench vise and a socket.
-Remove nut and washer.
-Apply a few drops of penetrating oil to the cotter bolt.
-Re-install the nut and washer so the top of the nut is flush with end of the cotter bolt.
-Select a socket in a size that fits over over the bolt head.
-Now arrange the cotter bolt and socket in open vise jaws so as the vise is closed it will press the cotter bolt head into the socket. These bolts are usually very stubborn and take considerable force to release. When they let go they reply with a dramatic CRACK, the sound of success.
-Remove from the vise and remove the nut and washer, then press the bolt out with your thumbs or at most a little tippity tip tap. It will drop into your palm in reusable condition.

I have never had a failure using this foolproof method.

a good one, to be sure, but if he's bent the cotter, it will only bend it more.

a good one, to be sure, but if he's bent the cotter, it will only bend it more.heh, heh.. he can smack it some more and bend the bolt back the other way. Then try the press method. :)

heh, heh.. he can smack it some more and bend the bolt back the other way. Then try the press method. :)

hell, if you've already got the bfhammer in your hand... it's more satisfying that way. ok, truth is i love my var press... ;-)

If he's already destroyed the option of re-using of the cotter bolts there's no harm in doing the above procedure without the nut and washer, just bare threads. This will provide the clearance or "travel" needed to push the bolt into the socket.

I cringe when this topic comes up and people start talking of swinging big hammers, delivering great, inaccurate wallops of destruction. Innocent spindles, cups and bearings being needlessly exposed to damage. The secret is to deliver concentrated, irresistable mechanical force exactly where it's needed.

We're working on machines that are built to high tolerances, using the proper tools and techniques, not knocking together some Homer Simpsonesque dog house.

In fairness, I've never removed cotters intending to put them back. I generally whack them out only when I'm modernizing ;)

If I were planning on reusing the cranks, I'd probably be a little more gentle with my hammer!

Personally I'd cut the spindles with a hacksaw. If the cranks are to be reused, remove the pedals, put the cranks in a 450-degree oven for half an hour, then either drive out the cotters with a hammer and punch or press them out with a vise (or an arbor press if you have one - most of us don't). The heat will make a remarkable difference in how easily the cotter comes out.

If you want to reuse the bottom bracket I would suggest refraining from hammering on the cotters in the first place, as this sounds to me like a good way to dimple the bearing races or crack the bearings. Press them out with a vise or a press instead. I'd use a stack of washers instead of a socket to support the back of the crank, since a socket may have a sharp lip that will leave marks on the crank. Get washers that have an inside diameter slightly larger than the big end of the cotter, stack them up and wrap them with tape to hold them stacked neatly, and position them carefully behind the cotter so it will slide into the hole. If you plan to reuse the cotter be sure to put a sacrificial nut on the threads, but I'm not sure why you'd want to reuse a cotter.

For that matter, I'm not sure why anybody would want to reuse cotter-type cranks, but then again I'm a really big guy. :-)

Dave

[EDIT: Maybe I should proofread once in a while!]

I had to totally destroy the cotter pins with an electric drill, blowtorch the remnants, and then bang the shredded tatters out with a hammer and screwdriver before the cranks would come off. Nothing less had any effect whatsoever.

IF you mushroomed the cotters, you are pretty much screwed.

This is why cottered cranks fell out of favor years ago. They suck bad!

Next time, back the nut off just to the end of the bolt and then whack the bolt. This will help keep you from mushrooming the bolt. There is a device that some old timer bike shops have to press the bolt out, but if you mushroomed the bolt already, there is nothing they can do.

Drilling out the bolt is nearly impossible without a machine shop because you have to drill perfectly straight which is very hard to do with a hand drill on a bicycle. Remember, the spindle is hardened. If you drill and damage the spindle, you are double screwed.

Be sure to support under the bolt. The whacking can damage the bearing cups. I broke some bearing cups trying to remove the crank arms once.

The rule of thumb is to:

1) make sure you have good support for the crank under the bolt before you start whacking.
2) Use a hardened pin to hit the bolt. Do not hit the hammer directly to the bolt. I use the spindle from an old pedal for this.
3) Use liquid wrench
4) tap the crank with the hammer in the opposite direction of the crank rotation and a little on each side of the crank to loosen it up a bit.
5) When you do whack, do it with gusto. It will come free only with a strong whack, but the light and medium hits only mushroom the bolt.
6) Maximum two or MAYBE three whacks and it is time to give up and bring it to an LBS that has a bolt remover. Don't mushroom the bolt!

I removed my last set of cotters by applying penetrant at both ends, then loosening the nut and squeezing them out with a large C-clamp, with a socket over the big end for pin clearance. It was easier on the pins than my usual hammering, and I reused them.

last resort: angle grinder will cut that f'in crank to hell and off. Screw the crank it's cottered anyway.

thanx guys, i was planing on ditching the cottered cranks. i will try the press method on one side, and the other side just may need to be cut off. for the press method, would a C-Clamp work? and what do you secure it to on the side of the non-threaded pin?

damn cottered cranks!!!

I'll second the old-pedal-spindle-as-punch method, it worked after I had really mashed the cotters into mushrooms. Use a vise grip to hold the punch!

but i need like 4 arms to do that method. haha

If he's already destroyed the option of re-using of the cotter bolts there's no harm in doing the above procedure without the nut and washer, just bare threads. This will provide the clearance or "travel" needed to push the bolt into the socket.

I cringe when this topic comes up and people start talking of swinging big hammers, delivering great, inaccurate wallops of destruction. Innocent spindles, cups and bearings being needlessly exposed to damage. The secret is to deliver concentrated, irresistable mechanical force exactly where it's needed.

We're working on machines that are built to high tolerances, using the proper tools and techniques, not knocking together some Homer Simpsonesque dog house.

Not only is your advice by far the best on this subject, but your delivery is hilarious!

but i need like 4 arms to do that method. haha

1. put your bike on the repair stand at just the right height so that the cottered part of the crank is resting on the pipe.

2. Put yer spindle/punch in the vise grips.

3. Hold the vise grips so that the spindle is perpendicular to the ground and right over the cotter. That's with your left hand if you're a righty, right if you're a lefty.

4. Take a hammer in your dextrous hand and carefully, forcefully tap the cotter out.

1. put your bike on the repair stand at just the right height so that the cottered part of the crank is resting on the pipe.

2. Put yer spindle/punch in the vise grips.

3. Hold the vise grips so that the spindle is perpendicular to the ground and right over the cotter. That's with your left hand if you're a righty, right if you're a lefty.

4. Take a hammer in your dextrous hand and carefully, forcefully tap the cotter out.



is each step for each hand? and i belive my #3 hand is my dextrous hand. thanx for the info. ill try all that minus the repair stand, i wish i had one... haha