I used a piece of metal pipe and a hammer to install these cotter pins on a new bottom bracket. They became loose so i removed and checked them and they got a mark on them from the axle. Do I have to file the corter pins down to make them fit? The question that arises to the mind: did I hammer on it too hard or not hard enough?
by erikwaebo
8 Comments
I forgot to include them in the picture, but I did install the cotter pins with the nuts and washers on
Use Blue loctite.
They come in different diameters so you may have a size too small, and the wedge doesn’t get enough surface area. It’s also normal for them to come SLIGHTLY loose after installing and riding the bike, and often have to hit them in again and tighten again. It’s the wedge that holds them in place, so it’s not about tightening the bolts and using locktite.
Since this was posted twice I’ll repost my response here:
The lost art of cotter pins…. New cotter pins come with a universal taper. Usually you would file the new pin to match the taper of the old pin. If you don’t have the old pin, then it is trial and error. If you get the taper wrong you’ll notice that the crank arms aren’t quite square to each other (Spence Wolf would say the cranks were out of phase).
So yes… assuming you have the correct diameter pins, they should be filed to fit, pressed into place and the nut tightened just to secure them.
Just a side note, when cottered cracks were popular even at the high end of racing tool companies made tools for holding the pin in a vise like the VAR 371. There are tools that hold both the old and new pin side by side so you can file the new to match the old….but they are rare at this point.
In my experience from something like 13 years ago? Switch to square taper if You can.
Just ask Sheldon! Dead but not forgotten…
https://www.sheldonbrown.com/tooltips/cotters.html
There’s never a scenario where you will have hit a cotter pin too hard. You’re trying to deform the (relatively soft) pin into the wedge shape to hold the pedal along the whole area of its flat section. Start by filing its profile as close to this as possible.
There is, however, a scenario where you hit it so hard you shatter a bearing. So don’t hit them quite that hard.
Depending on where you are, find somewhere/ someone with a cotter pin press. There’s a bike coop near me that you can rent a work stand by the hour and it has more tools than you can imagine, including a cotter pin press.
what u/NthdegreeSC said and also remember to re-tighten them with a few whacks after riding for a bit