got to service a bb with cottered crank.
i've seen advice on how to remove them, but does one hit them out at the head or bolt end?
i've seen advice on how to remove them, but does one hit them out at the head or bolt end?
cotterless cranks
- Thread starter alecstilleyedye
- Start date
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Loosen the nut a couple of turns. Spray releasing oil on the cotterpin threads and down the hole.
If there is thread left, put another nut on and lock the two nuts together.
Get a piece of nice hard wood and use it between the hammer and cotterpin nuts.
Hopefully, the cotterpin will loosen. Remove the nuts and gently drift the pins out.
New cotterpins these days are soft as shite and the threads strip easily.
New cotterpins need filing to enlarge the flat.
When reassembling, hammer the cotterpins home. DO NOT try to pull them with the nut. After a few dozen miles, hammer them again and take up the slack in the thread.
Good luck.
If there is thread left, put another nut on and lock the two nuts together.
Get a piece of nice hard wood and use it between the hammer and cotterpin nuts.
Hopefully, the cotterpin will loosen. Remove the nuts and gently drift the pins out.
New cotterpins these days are soft as shite and the threads strip easily.
New cotterpins need filing to enlarge the flat.
When reassembling, hammer the cotterpins home. DO NOT try to pull them with the nut. After a few dozen miles, hammer them again and take up the slack in the thread.
Good luck.
mickle
innit
Bolt end. It's really easy to bugger them up though. Check how they are installed before removing them. I can't remember how they go but there is a wrong and a right way and they need to match, ie be rotationally symmetrical.
Remove the nut and spray some penetrating oil into the crank hole first and let them soak.
I cant remember the last time I saw a cotterpin press, unless they are particularly mashed you'll be knocking them out with a punch.
Replace the nut so that it sits flush with the end of the thread (to protect the thread from damage) and using a blunt punch and a medium weight hammer tap the pin through. Its really important that you hit it straight. And hard.
If there has been any play in the interface of pin and crank they'll be mashed and really hard to remove (the pins are softer than the axle or crank) but if it all goes to sh*t you can resort to drilling them out.
Remove the nut and spray some penetrating oil into the crank hole first and let them soak.
I cant remember the last time I saw a cotterpin press, unless they are particularly mashed you'll be knocking them out with a punch.
Replace the nut so that it sits flush with the end of the thread (to protect the thread from damage) and using a blunt punch and a medium weight hammer tap the pin through. Its really important that you hit it straight. And hard.
If there has been any play in the interface of pin and crank they'll be mashed and really hard to remove (the pins are softer than the axle or crank) but if it all goes to sh*t you can resort to drilling them out.
tyred
Legendary Member
They go in from different sides so that when you hold the crank vertical, the nut on one side will be pointing forward and t'other will be pointing backwards. If they really are tight to drive out, it may help to cut a length of heavy steel pipe or something to the right length to fit between the crank and the floor to support it while hitting them. The important point is to really hit them a good hard thump. If you just tap, tap at them, you will definitely rivet it in and will definitely need to resort to the drill. If you do need to drill, make extra sure you are drilling straight through the pin. The bottom bracket spindle is strong enough to snap the drill bit and then you really do have a problem.
hubgearfreak
Über Member
don't fear them. if you follow the instructions, they work fine.
take time to properly read and understand these two links....
http://www.sheldonbrown.com/cotters.html
http://www.sheldonbrown.com/tooltips/cotters.html
take time to properly read and understand these two links....
http://www.sheldonbrown.com/cotters.html
http://www.sheldonbrown.com/tooltips/cotters.html
