Cotter Pins

[RyanW]

After successfully and easily re-greasing my headset (took me 20 minutes(And fixed the problem, turns out there was no grease in there to begin with)) i decided to have a go at the BB (its the next this along).

But i have a problem, the blasted pins will not budge (seems this has been an issue since their invention...)

I have removed the pedals and the holding nuts, but the pins, no matter what i do, will not budge.

I have tried hammering, soaking with oil for a few hours and hammering. I have read sheldons guide and used a small piece of metal as a pin, still not moving.

What other options / tricks are out there?

On a side note, how do i ensure the replacement pins are correct size, or would it be easier to replace the arms, and BB?

 

[gbb]

One of the best ways to remove the cotter pins was to undo the nut a couple turns, hit the nut squarely, driving the pin out, then undo the nut a bit again...etc etc.
With the best will in the world, sometimes it just didnt work, the threaded section of the pin would bend and thats it goosed.
Sometimes it'd be a case of sawing the thread off so you could use a pin punch and get a good clean hit on it...but ultimately they were swines sometimes. There were also good cotter pins and cheap cotter pins, they were very prone to bending.
I think they're pretty standard size wise...

 

[RyanW]

I tried the method of using and not using the nut.

I have seen a cool trick with a vice and a spanner (You use the spanner as a spacer and the vice to force the pin out. Just need a vice now, and as i have mushed up the bolt, something to extend it.

 

[Mark Grant]

I use a socket on an extension bar underneath the crank down to the ground so that when I whack the cotter pin it receives the full blow and the force is not diminished by the tyres acting as shock absorbers.

 

[sidevalve]

As above stand the bike on stone or thick concrete base, use a steel stand for the pedal and strike vertically down with a heavy hammer, don't mess around with a toy what you need is a solid bang [best get someone to hold the bike, you can't do two thngs at once].
If you've bent or mushroomed the head oversize for the hole and you do have to cut it off use a good solid punch
without a point [you want to drive it out not expand it].

 

[tyred]

The single most important point is to really hit hard, ideally with support underneath the crank. I've seen many people who sit tip-tapping at cotters and similar pins in other applications and end up rivetting them in place when a hard crack would probably have moved it in the first place.

If the pins weren't tight in the first place, they may be bent. If all else fails, drill a 3/16" hole through the centre of the pin and try again. This will be enough to relieve internal stresses. Heat might help but careful with the blow lamp if you ant to preserve the paint on the frame. It won't do the chrome plating on the cranks much good either. It is important to drill through the centre, the bb spindle is hardened steel and will snap a HSS drill bit if you catch it.

 

[RyanW]

RAWR,

The damn things are still in.

I have now tried the vice method and a bigger hammer, my main problem is not having a punch finding something to strike.

heating or drilling is my last resort if this fails. That or using a grinder to remove the crank arm and buying a new one!

 

[RyanW]

Done,

The method, a mixture of everything.

Tools =

One 24volt drill
5 graduated metal drills
two punches
Club hammer
3 people
6 mugs of tea
about an hour
Understanding neigbours

Method: We gradually drilled out the cotter, only breaking two drills (we struck the crank) going from the side that wedges it in, rather then the nut end. first drilling a starter whole and slowly using bigger drills, we tried to avoid the crank at the expense of the crank arm. (Id rather buy new arms then new drill bits)

Once as much was drilled out as possible we wedged in a punch (using the graduated drills has created a kind of ledge inside which held the punch, this was more luck then planning)

Then we pretty much wacked the hell out of it.

After about 10 big hits it popped out.

im now trying to decide if i keep the BB / crank or replace it with something more, user friendly.

 

[tyred]

What is the bike? If it's a roadster or a really old road bike, definitely leave it as it is. A road bike, post 1960s would be fine with square taper cranks, look for period Stronglight and Milremo chainsets on Ebay, they're rarely that expensive.

There is a lot of nonsense talked about cotterpins but it they are installed properly in the first place, they should give no trouble in service. Push the pin in, put on the washer, tighten nut (careful not to strip it as these are soft metal), hit the other end a few hard whacks with the hammer, tighten the nut again and repeat until the nut no longer comes slack when you hammer. The purpose of the nut is not to pull the pin into place but to hold it there when it has been pressed or hammered into position. Then ride for about 50-60 miles and check the nut is still tight. If not, hammer it tight again. The nut will never pull it into position properly without a press or hammering, it will work loose and bend the pin, make annoying clicking noises and probably ruin the crank. Also ensure you have a matching pair of pins as they have different tapers and two with different tapers will mean the cranks will not be in line. Remember that the pin on one side needs to be point forward and the other needs to point back.

 

[Garz]

Pictures of this kerfuffle would have been great as a guide for poor forumites whom might get into this situation.

 

[RyanW]

Pictures of this kerfuffle would have been great as a guide for poor forumites whom might get into this situation.

Getting the camera out was the last thing on my mind! i would of ended up hitting the pin with the lens!

 

[guitarpete247]

My dad couldn't see why they moved away from cotter pins to square taper.

I hated them.

They either won't come out or won't tighten properly. I remember cranks clonking every rotation.

 

[Smut Pedaller]

I've had to resort to drilling them out once, but otherwise as long as you have a solid connection from the crank to the ground (an old steel seatpost works well) and have a good whack at it, it usually isn't a problem. Whacking away at it without any connection to the ground is really just damaging your BB, all your energy is going into compressing the tyres rather than into the cotter pin.

 

[RyanW]

I think after 35 years the pins and arms had become one, even after drilling they still required a good wacking to get them out, the wheels were off the bike as was the head set, i had the bike propt so that the arms were suppoirted by bricks either side and had a dumbell bar between the pin and the floor (there was a hole in the middle to the pin would have fallen through.

If you can picture that!