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Old 11-08-10, 05:36 PM   #1
Russcoles11
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Stuck Cotter pins

Just got myself a 1975 Dawes Kingpin and need to strip it down for a repaint. I have managed to remove everything except the cranks. The Cotter pins simply won't budge even when hit with a hammer. Any suggestions?
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Old 11-08-10, 05:44 PM   #2
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a press. Find a shop that's been open since 1975, and have them do it.
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Old 11-08-10, 07:01 PM   #3
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use a c - clamp and a socket for the press. put the socket over the head of the pin and with the help of the c-clamp you should be able to "press out " the pin(s). if you have bent the pin(s) yes they will be harder to get out and also use some oil.
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Old 11-08-10, 08:49 PM   #4
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if you don't have a socket and a c-clamp and you have a skateboard a vise according to this video it might work lol !

http://www.youtube.com/watch?v=mybfNsm1XwM
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Old 11-08-10, 09:53 PM   #5
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Or hit it with a bigger hammer. This may sound like a joke, but I'm serious.

I once had a really stubborn cotter pin. I drilled a hole right down the center, and it still didn't want to move. I hit it really hard, over and over, and it eventually came out.
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Old 11-09-10, 09:03 AM   #6
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Or hit it with a bigger hammer. This may sound like a joke, but I'm serious.
.
because, with luck, you'll bend the spindle, and have to buy a sensible crankset? Seen lots of those and a number of "bent the threaded bit that the knuckle head with a hammer was bashing", which also provides an excuse for a new crank.

There's a proper tool; it ain't a hammer. They're not unusual. They're not hard to use. Someone who owns one won't charge you much for using it on your bike.
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Old 11-09-10, 11:15 AM   #7
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drift punch will concentrate hammer blows on the end of the cotter,
a hex head bolt you can bang on will do, most likely..

But I'd seek out a shop with a cotter press 1st, you may be able to re use the cotter thereafter.

Bang it out and you will need to file the taper on the new one , until it fits properly.

threads not munched up in getting it out a + ..

Last edited by fietsbob; 11-09-10 at 12:29 PM.
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Old 11-09-10, 12:15 PM   #8
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dscheidt, we used a hammer in half the shops I worked in, in the cotter pin days. So to me, it's one of many possible tools. Sure, I prefer the cotter press, but since I don't have to work on cottered cranks often any more, I'm not buying one. Having a shop do it, though, is a good idea.

I never did any damage to any part of a bike while banging out (or in) a cotter pin. It's not a concern for me.
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Old 11-09-10, 01:32 PM   #9
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They're called cotters in the USA. Cotter pin has a different meaning here.
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Old 11-09-10, 03:57 PM   #10
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The spindle mashes notches in loose cotters when the left pedal applies power unless the bike has a coaster brake. The cotters will therefore hang up on the spindle when you try to remove them.

The right crankarm does not put much torque on the spindle because the sprocket is attached to it. When the left pedal is pressed, then torque goes through the left crank, the left cotter, the spindle, the right cotter, then the right crankarm, then the sprocket.

Whatever else you do, put backward torque on the left crank arm by making the cranks horizontal with the left crank arm pointing backward and push down on the pedals, or stand on the pedals with the crank arms horizontal and the left crank pointing backward. Then the cotters will be in a better position to come out easier if you don't disturb the crank much before trying to remove them after this.

If the bike has coaster brakes, both sides of the cotters will be notched because they take torque in both directions.

Last edited by garage sale GT; 11-09-10 at 06:01 PM.
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Old 11-09-10, 04:57 PM   #11
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When it's in that stubbornly you DO NOT need a press or have to worry about bending the threaded stud. Here's how to get stubborn ones out.

1. Tap the stud back and forth til it breaks off.
2. Add penetraing oil, heat 1st if you like, especially if it looks corroded.
3. Tap the crank toward the center of the bike. Doing so can help break free adhesion between the pin and spindle
4. Align the cranks as recommended above.
5. Support the crank over a VERY solid surface with an opening for the pin (machine vise, iron pipe on cement floor).
6. Place a flat punch into the handy recess in the crank (from removal of the threaded stud).
7. Whack away - odds are it will come out. If not drill out the pin.

This method is the best way to remove stubborn pins with minimal damage to the cranks or bearing parts.

Last edited by cny-bikeman; 11-09-10 at 07:48 PM.
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Old 11-09-10, 07:43 PM   #12
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dscheidt, we used a hammer in half the shops I worked in, in the cotter pin days. So to me, it's one of many possible tools. Sure, I prefer the cotter press, but since I don't have to work on cottered cranks often any more, I'm not buying one. Having a shop do it, though, is a good idea.

I never did any damage to any part of a bike while banging out (or in) a cotter pin. It's not a concern for me.
Bikeshop mechanics do a lot of things that I would never do to my own bikes. The owner of the shop where I worked was so cheap that he made us reuse bearing balls unless they were visibly broken. He had us clean them by spraying them with WD40, which he bought by the case. He wasn't too cheap to buy a VAR cotter press, though. We sold Peugeots, Raleighs and Columbias, so there were pleanty of cotters to deal with. The worst ones were the ones that somebody had beat on with a hammer. I saw a lot of hammer dinged cranks, too.
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Old 11-09-10, 09:07 PM   #13
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Bikeshop mechanics do a lot of things that I would never do to my own bikes.
Jeez, if you won't bang out cranks, how DO you get your aggressions out?
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Old 11-10-10, 05:00 PM   #14
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I agree with noglider ,how do you if you can't ?
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Old 11-10-10, 05:32 PM   #15
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Just like a lever is useless without a fulcrum, hammering without a dolly or anvil to concentrate the force won't do anything but mushroom the pin. You want to support the crank arm with a high inertia mass, so all the hammers energy is concentrated on moving the pin and not anything else.

If you have a bench vise of decent size stand a piece of 3/4 inch water pipe up resting on the bottom and clamp it. Now have a friend hold the bike over the vise with the crank supported on the pipe, with the pin in the hole. Since you're probably timid about crushing your hand, hold a punch in a vise-grip, and give it a solid blow as if trying to send the pin down the pipe, through the vise and on it's way to China.

If you've already mushroomed or bent the screw cut it off flush and do as I said above.

You don't have to exactly follow the steps I've outlined, but do have to properly support the crank arm, and deliver a serious blow. Cotter pins need to be removed with one good shot, delivering more concentrated energy than they can dissipate by distorting.
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Old 11-11-10, 10:11 PM   #16
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I've had pretty good luck lately on several cottered
cranks with fairly old and rusty cotters by using a
twenty dollar drill press vise as the press with a
9/16 ( or thereabouts) socket as the negative space.

First you oil up the buggers with Triflow, PB Blaster
(as seen on TV), or your favorite penetrating oil,
having loosened the nuts to provide access for
squirting the oil. Now the hard part .. wait ten
of fifteen minutes for the magic of chemistry to
do its thing. Leave the nuts on, but with about
an eighth to a quarter inch of space so the cotter
can move as you press it.

Put the drill press vise on the crank with one face
pressing on the nutted pin end, and the socket
on the other face to provide negative space for
the pin to move into. Crank it down hard .. wait,
crank it down hard again.. wait again. They usually
pop free by about the third application of force.

You may need to put a short cheater on the drill
press vise handle as they are too short to provide
much leverage. Make sure the vice screw is well oiled
or greased.

These are readily available at Home Depot or any
of the chinese tool import places. They work as well
as specialty cotter presses at a fraction of the price.

I have hammered out a few over the years and always
found it to be a somewhat risky and problematic
procedure. This works better, although I am forced
to agree with Tom and Bikeman that it is not nearly
as satisfying as pounding on something with a hammer.



Mike Larmer

Last edited by 3alarmer; 11-11-10 at 10:15 PM. Reason: add thought
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Old 11-12-10, 07:18 AM   #17
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+1 I have a drill press vise myself, works well as described above. Not sure its worth buying one if you don't have one already, but you should be able to borrow one from a tool loving friend.
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Old 11-12-10, 02:56 PM   #18
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I never even heard of a drill press vise. What a great idea. It's cheaper and more generally useful than a cotter press. I can't think of what else to do with it, but I'm sure I will.
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Old 01-21-14, 11:12 AM   #19
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Mike's vise as cotter press is a very effective technique, and certainly makes sense compared to buying a dedicated cotter pin press.

OTOH, done right, hammering is also very effective. The key to hammering a pin out is to ensure that 100% of the energy goes into moving the pin.

That first requires that the crank is supported against a high inertia object (anvil) so it cannot move when struck, and roll with the punch, so to speak. Proper support also ensures that none of the hammer's energy goes to the bearing.

The second key is to deliver a hammer blow with more energy than the pin can absorb by mushrooming. Think of breaking boards with a Karate chop. If the boards break your hand is fine, if the boards hold --- well something has to give.

People should use whatever technique is best suited to what they already own, rather than going out and spending lots of dough unnecessarily.

The one thing they should NEVER DO is to hammer on a pin without supporting the crank. This will not only mushroom the pin, but is likely to damage the bearing surfaces.
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Old 01-21-14, 11:19 AM   #20
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Adding to above ..
Mushrooming and making the cotter pin un usable, again, is why backing off the Nut,

but leaving it in place, with a gap to move it inward, would help preserve the threads..
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Old 01-21-14, 11:56 AM   #21
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The key to hammering a pin out is to ensure that 100% of the energy goes into moving the pin.......That first requires that the crank is supported against a high inertia object (anvil) so it cannot move when struck, and roll with the punch, so to speak. Proper support also ensures that none of the hammer's energy goes to the bearing.
+1 At the risk of being repetitious, I'll also emphasize the absolute need to support the crank arm with something solid if you are using a hammer to 1) absorb the hammer blow, 2) prevent bending the spindle, 3) prevent bending and distorting the frame's bb shell. A length of steel pipe, say 3/4" diameter or so, stood vertically on the floor and solidly shimmed so it fully supports the crank arm with the cotter head centered over the opening is a good way.
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Old 01-21-14, 12:17 PM   #22
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.... A length of steel pipe, say 3/4" diameter or so, stood vertically on the floor and solidly shimmed so it fully supports the crank arm with the cotter head centered over the opening is a good way.
Do not place the pipe directly on the floor, unless you want to leave pipe rings. Use something to protect the floor by spreading the lead. A pick of 2x4 laid flat is fine.
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Old 01-21-14, 01:36 PM   #23
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Do not place the pipe directly on the floor, unless you want to leave pipe rings. Use something to protect the floor by spreading the load. A piece of 2x4 laid flat is fine.
Good point. Stack wood or whatever material to protect the floor (even concrete) from the pipe end.
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