Where can I buy this shimano part?
 

I forgot it existed, and broke it while trying to remove the crank arm.

It's the plastic plate w/ the pin in it. Part #7 in the diagram.

Thanks for any help,
B.
http://www.imagehosting.com/out.php/...crankpiece.JPG

Try calling Shimano's Tech service at 1-800-423-2420. They may send it to you at no cost. I had one of their brake lever's cable retainer barrel snap off and they sent me a replacement gratis. You can't e-mail them but the phone number works.

As long as you're proactive about making sure those pinch bolts are torqued properly you don't really need that retaining pin. Shimano didn't start shipping cranks with those until sometime earlier this year and that had been after Hollowtech II had been around for quite a while.

The reason it's "necessary" is because a lot of people aren't good about making sure those pinch bolts are secure. They do loosen over time. The pin just keeps that crank from falling off should the crank loosen.

Buy a torque wrench. Use it.

I just bought a brand new Shimano Saint crankset and it didnt even come with that piece.