How to remove stuck cotter pins ?

[greyingbeard]

anyone ?
do I need something like a g-clamp with a slot in the foot ?

[Brucey]

a length of thick-walled tube under the crank braced against a concrete floor gives (light) hammer blows somewhere to react to. I have found that many small taps with a hammer often count for more than one big blow, but also a straight blow counts for more than anything else; thus it is best if you use a drift of some kind.

You can buy cotter pin presses (some at vast cost) but if the cotter is well seized and/or corroded you will struggle even with those; the required load can be many tonnes.

cheers

[foxyrider]

That's one bit of retro best left in the past!

[greyingbeard]

agreed foxy but they have to come off first

[robgul]

Assuming you have the nuts off the cotters .... did this not long ago (with an assistant holding the bike) : place BB shell supported on a concrete block (with a bit of wood and bit of old carpet to reduce scratching risk) hold crank horizontal (assistant's other hand) - use a punch/drift* and a hammer with short sharp taps ... increasing as required - did the trick in no time.

* If you don't have such a thing an old bolt of smaller diameter than the cotter would substitute ... but mind your fingers with the hammer.

Rob

[Brucey]

resting the BB on a concrete block puts impact loads through the BB bearings; this is the main reason for suggesting a thick-walled tube beneath the crank so that the loads are reacted directly to the ground instead of through the bearings.

cheers

[LollyKat]

That's one bit of retro best left in the past!

Indeed. A combination of penetrating fluid, local heat and hammers usually did the trick in the end but a couple of times I ended up sawing the crank off with a hacksaw.

[drossall]

My dad taught me to put a heavy weight below the crank (but not below the pin, obviously), so that there was more inertia. This helps to protect the bearings. I'd use a sledge-hammer head for this purpose. Undo the nut far enough to be flat with the end of the pin, so that you have more to hit with a much lighter, standard hammer. By all means use easing oil for a while first, as well.

However, I've twice ended up drilling through the pin. Once was with dad again, and the second time, years later, I repeated the process and got this result.



The easiest extraction I ever did was when a friend complained that his crank was moving forwards and backwards relative to the other one. It was, by about 90 degrees Here's why:

[bobc]

Remember you can always use an engineers vice as a pretty handy press. trouble with hammering is that's how you rivet things permanently into place. The nut can be left loosely on the cotter to give the press a wider base to press against.

[PT1029]

If your cotterpin is stuck, but the crank has had some rotational play in it, you probably have a cotterpin with the V shaped slot in it (as per Drossall's photo). If this is the case, you will need to hold the cranks parallel/in line (ie, stop one of the from drooping down while you hit the cotterpin), otherwise the pin can't slide out, as the edge of the BB axle flat is caught in the V shaped slot.
As mentioned, a firm support to crank (not BB shell) cannot be over emphasised, plus prolonged penetrating oil/plus gas or equivalent helps, plus enough heat (lots/excessive!) to make Brucey wince at the damage to the metal grain structure......!
I think the worst case I had years ago involved angle grinding the crank off....

[greyingbeard]

If only there were a little clearance between cranks and frame, I could grease and adjust the bottom bracket leaving this stuck stuff in situ.
I want shiny new cogs, I have them, got to get the old ones off first

[Brucey]

a note of caution; if the bike is an old Raleigh (or other Raleigh-owned brand) it may have 26tpi BB threading. So any 'destructive removal' you might indulge in may come back to haunt you, if it turns out the new bits don't fit for some reason...

cheers

[JohnW]

Cotterpins were the absolute bane (or pain even, or blight if you like) of my cycling life. I didn't have a vice and I could never file them to just the right angle. Right up to the mid-sixties (I was in my early twenties then) I had to use them until I could afford alu/cotterless. I don't know about alu/cotterless cranksets being the answer to the maiden's prayer, but they were the answer to mine.

I was lucky, however, because an elderly cyclist (Clem) lived nearby and he was always glad to fit them for me; it took him about five minutes in his shed to file them to a perfect fit, and I think the perfect fit was part of the answer to problems of getting them out. When mine were stuck in I supported the bottom bracket on a lump of softwood (not on the end-grain, because there's no give in the end-grain), I got a piece of hardwood (never metal) and laid it on the end of the cotter, and whacked it with a wooden mallet. Always support the BB, never let impacts travel through the frame and wheels to the floor........always lift the wheels off the floor. That's a fiddle to support the bike, but you can do damage otherwise.

Clem never had a bike-stand or a proprietary tool for getting cotters out, but he never seemed to have any trouble - he'd made some sort of a contraption for himself that would use unscrewing of the cotterpin-nut to push the cotter out. Sometimes the threads would strip and he'd have to revert to the wooden mallet method that he'd taught me.

To be honest, after some hard, salty winters the cotter was stuck so well that I resorted to a hammer with nothing covering the end of the cotter, and whacked it with all my might! That used to destroy the cotterpin of course, and I had to go round to Clem's again to ask him to file me another pair.

It must be 50 years since I did battle with a cotterpin - thank goodness.

Cotterless cranks are one of the best improvements ever.

[JohnW]

By coincidence, in a thread titled "Have we seen this?" (on this section), Philip Benstead has posted information which will probably help - a purpose made gadget intended to do just the job. I wish I'd had one of these..........say "thank you" to Philip.

http://www.bikesmithdesign.com/index.html

They are American though, so you can't just pop round the corner and buy one!

[Brucey]

I know someone who has that tool. It is quite good but you still need to use the hammer on ones that are well stuck. The tool is also rather pricey. So overall, probably not worth the money I'm afraid.

cheers