A Cotter Pin Press by George Hagerty

. Needing to access my gearbox for inspection, I began the long suffering duel against a recalcitrant hand shifter cotter pin; soaking in oils, brass drift pin and hammering on loosened nut run up to end of pin all bore little movement over 2 days. Obviously not wanting to bung the threaded end I was at a stop. Understanding in advance from Duane Ausherman's incredible BMW website (http://w6rec.com/duane/bmw/index.htm) what the cotter pin looked like (NOT what we usually think of as a "cotter pin" - aka a 'split pin') and how it behaved (slight deformation against shaft grove over time) I thought there must be a way to press the pin out. And then it hit me: reaching back into the files of my mind I remembered building pedal bikes in my teens and that the lower crank set and pedal have the very same type cotter pin affixing the crank set (and opposing pedal arm) to the bottom bracket drive assembly. These get stuck in the same way - press fit, flat faces into slots in axles with little room to swing a mallet and get good strikes for removal. A quick search on the internet finds a coveted (by pedal bike enthusiasts) albeit no longer produced "cotter pin press" by Park Tools on Ebay for upwards of $60. So, borrowing from the pedal bike world I decide to make my own cotter pin press. Cost: $5. Time: 10min. Operation: Priceless.



1. Purchase a minimum 1 1/4" throat "top beam clamp" from a hardware supply store.

Pedal Bike “Cotter-pin press” = ‘Top Flange Beam Clamp’

FASTENAL

http://www.fastenal.com/web/home.ex

MCMASTER-CARR

http://www.mcmaster.com/#

***If you don’t know of McMaster-Carr you are missing one of the greatest, universal, most widely stocked and quickest shipping uber-hardware supply houses of all time!


2. Grind bottom angled interior face (where set bolt is) square - to allow enough width to get around hand shifter arm.



3. Grind tops of clamp ends down to allow good alignment with gearbox cover face and, most importantly, that the square head clamping bolt (which will become your driving force pin) is perfectly in line with the cotter pin. Case faces are compound angles in this area so grind as needed - not necessarily flat. Grind and test fit until perfect.



4. Grind a groove in the end opposite the square head clamping bolt - this groove will allow space for the head of pin to exit as it moves outward during pressing/removal.



5. Thread a 3/8-16 x 4" hex bolt thru bottom of clamp to act as a steadying handle during operation.



6. As the case cover is beveled at hand shifter area and your clamp will stand off the case on right hand side, I taped a 1/2" flat washer ('thick style, not fender) to back up the clamp and prevent misalignment during torquing.



7. Assume you've added oil to prep for removal and, steadying clamp, slowly turn clamping bolt - if you are straight in alignment, the pin will ease right out!





I used to love to ride pedal bikes after having rebuilt them. Now, 35yrs later, I love to ride my Chang ever time after I fix her….!

NOTE: I have not had to remove the kick start pedal arm yet, but when and if I do and that pin causes trouble, I will make a larger press for that one…

George Hagerty