I just installed 4.10 gears and a new eaton posi in my 12 bolt. I could not get my new crush sleeve to crush! When I tightened the pinion nut, there was still play in the pinion gear, when I put the old collar on and tightened the nut, everything snugged up? I did this a few times till I just decided to use the old collar (yikes). I hope this will be ok. Went for a test drive and everything went well. What did I do wrong?

It takes about 300 foot pounds to crush the spacer. You just didn't try hard enough. The bearing preload needs to be set at 19 to 22 inch pounds with new bearings, no matter what spacer you used. If you got this correct, and you used lock tight on the threads, and the nut has at least 150 foot pounds of torque on it then it will be fine.

Big gear heads preachin you Gospel,I worked at an old shop along time ago and they built rearend gears as a specialty...they had a 3/4 breaker bar about 3 ft long thats only use was to tighten down on the crush sleeve,sometimes it would take two guys pulling on it.Then they would go for a drive,come back and crush some more or not depending on whether they had it right or not,so dont be afraid to lay in to it!