# Ruined Crank Arm Binder Bolt Threads



## the freewheeler (Feb 14, 2016)

Hello!

I recently picked up a 1944 BSA Airborne that I'm in the process of cleaning up. In the process of cleaning the frame, I attempted to remove the crank arms. The binder bolts were/are stuck on really hard, so I broke out the hammer to tap them out. Little did I know, but the quality of the bolts are cr*p (metal is EXTREMELY soft), so the only result of hitting the bolts was that the end of the bolt flattened, ruining the threads. The only fix for this I know of is to file flat (taper) the beginning threads, but this actually made it WORSE. I've used this same method many times with 100% success, but not this time for whatever reason. To say the least I am very, very p*ssed off now that these are ruined. Does anybody have any recommendation for something to try? I'll be forever indebted...

photos:


----------



## Andrew Gorman (Feb 14, 2016)

Just get some new crank cotters- they are supposed to be soft and replaced each time you take the cranks apart.  Local bike shop should have some if they have been around a long time, or check eBay and the web.  There are two different sizes, so measure the ones you have.


----------



## morton (Feb 15, 2016)

They can be real nasty to remove.  I have had to drill them out before I made that homemade Harbor Freight cotter removal tool posted on this or another site.


----------



## Iverider (Feb 15, 2016)

I mashed a cotter pin ONCE trying to remove the cotter pin but it was a 1965 Raleigh.

Here's an easy way to do remove pins without mashing them.






Put the hammer away. No more hammers on antique bikes.

http://bikesmithdesign.com sells cotters and pin presses. If you can measure the angle of your pin, they should be able to hook you up with the proper diameter and angle for a new pin.


----------



## Gordon (Feb 15, 2016)

If your bike shop doesn't have them, I have a couple sizes. As stated, measure your old ones so I can make sure I supply the correct size.


----------



## berniebike (Feb 27, 2020)

the most common on older English bikes was 9.5
there are at least 4 different sizes used on 1960's thru 1980's bike.  (possibly older too but I've only been in the business since 1971)
9 and 9.5 being the most common.
2 smaller diameters mostly used on Italian bikes.
most bike shops wont even know what they are now adays


----------



## 38Bike (Feb 27, 2020)

Bicycle Crank Cotters


----------



## PCHiggin (Feb 28, 2020)

Ditto,They need to be pressed out.


----------

