Monday, 4 February 2008

Cotter pin trouble



Well my initial plan on my day off was to clean my Humber crank set but with time on my hands I decided to take the cranks off the bike which turned out trickier than I thought it would be. The left hand crank cotter pin came out ok with a few solid taps of the hammer but this was not the case with the right hand crank cotter pin which was put in by Hercules himself . I don't think the cotter pins had been taken out for many years and I guessed my father who owned the bike made sure they were in really tight when he last did them. After removing the left hand crank and un screwing the lock ring and bottom bracket cup I discovered that the bottom bracket was almost void of grease so I was glad I had started to pull the crank set off. After some heavy bashes with a hammer ( being careful not to miss and hit the crank arm ) the threaded end of the cotter pin bent over render it useless. My next plan was then to cycle to my mates bike shop nearby and see if he had a Park cotter pin press tool . I had one of these fantastic tools when I lived back in New Zealand for fitting cotter pins & removing them, but alas my mate who owned the bike store didn't have one or the need for one. So after buying some new cotter pins at the bike shop I then paid the home center a visit for some CRC spray and a metal punch to attack the stubborn cotter pin. My next job was to cut of the remainder of the bent thread from the cotter pin and drill a hole down into the cotter pin . Not having an electric drill meant this task was preformed by a hand drill which tackled the job ok but it took a long time and at least with a hand drill I was able to be rather careful not to drill off center and damage the bottom bracket shaft. After I had drilled down into the cotter pin and made a decent sized hole I then put the metal punch into the hole and even then it took a great amount of brute force to remove it . After several hours and using my best foul language directed at the stubborn cotter pin I was most relieved when it finally came out. I'm sorry there is no photo of me hand drilling a cotter pin out as I'm sure most bicycle mechanics would get a laugh out of it at least, but under the circumstances it was my only option. After cleaning the cranks and bottom bracket cups, locknut etc I was ready to re assemble it. One think I noticed was that inside the bottom bracket shell was a strong piece of sheet steel made into a tube to prevent any stray ball bearing's etc from falling down into the previous open tubes converging inside the bottom bracket. This was also positioned to keep the bracket cups at exactly the right distance apart . The above photo's show the current state of my Humber undergoing it's winter service, while the weather is too bad for cycling.

3 comments:

Philip Caines said...

I am so angry at my right cotter pin right now!

Good to know that others are having the same pain. So now I know there is no easy way to take care of it, and that I have hours of heavy banging ahead of me.....

Great....
Phil

Teethbrush said...

next time, try a bench vice. use a socket on the non-threaded end. bear in mind, it will take a good deal of force. i crank on it, let it sit for a sec, and crank again. repeat until BANG it pops out.

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