Out of curiosity, what is the proper procedure once proper torque is met?

Do you over tighten to get the cotter pin in, or do you back it off?

I know what I did, but I don't know if it was right. I also replace mine a month ago. I really should have checked when I did it...

And to respond to the original question, I did not have the issue you did with the stud turning. I did have it bolted to the knuckle and a jack lightly raising the a-arm to help the upper and tie rod stud go into their proper positions.

 

I just slightly over torqued the nut to fit the cotter pin. Trying to back it off just made it break free and got very annoying. Also realized that over-torqued is better than under-torqued equaling a stronger hold. And yeah, I didn't gorilla tighten the nut to were the bolt can snap. just a "slight" over torque

 

I just asked the same question on another forum, and most people say overtorque. I agree with that, but not because it gives a "stronger hold" because it doesn't. The little overtorquing I did to get the cotter in didn't feel like a big deal.

And by the way, the stud will not snap if you overtorque it, it is a heat treated part. The nut will strip. The nut is a softer metal and designed to be the failure point in case of overtorquing. This is why I always advise against just getting grade 10 bolts to replace toyota bolts. Sometimes softer metals are chosen for a reason. Not always, but sometimes.