Ok so i started doing the open diff. to the auburn posi swap today, i got it all set up and in but when i put the axles in and tighten down the bearing caps and go to spin the tires it acts like its locked up and wont move and was wondering if theres a cretin way it has to go back in. the gears at the same ratio both 2.73s should i just use the gear off the open diff on the auburn? or would that not matter?

 

So, you changed the carrier but not the gears? Or did you get new 2.73:1 gears to replace the old 2.73:1 gears? Either way, you probably need to change the carrier shims. The pre-load, backlash and contact pattern all need to be re-set. If you also did new gears, what did you do about the pinion depth? You probably don't have the tools to precision-measure the stock carrier and the Auburn, but if you did, you'd likely find slight differences. Even a 0.005" difference can cause binding, if shims aren't changed to compensate.

 

Put whatever gears were in the car before, back in.

What did you set the backlash to?

 

even though you put the original pinion and ring gear in, it will still be a little off because the crush sleeve is already crushed...

 

Let's hope the OP didn't disturb the pinion, for which there is no need if just swapping out the carrier.

If he did, best to just throw the whole ball of wax in the trash and start over; that will cost about half as much, or less, than "fixing" the mess that got created.

 

All Im doing is swaping the carrier the pinion has not been touched its still bolted to the drive shaft

 

Then the crush sleeve is a non-issue. Although, with used bearings, probably wouldn't hurt to tighten it a little bit (like, 1/16 turn or so), just to take up the slack in the old worn pinion bearings; but not necessary.

Put your "old" ring gear onto the "new" carrier. Install it with the "old" shims, the ones that came with your "old" housing. You should observe something in the neighborhood of .008" - .012" of backlash. A little more is better than not enough, but it should hopefully be in that range. If so, put the axles back in, put the cover back on, add a bottle of posi additive, then fill it the rest of the way with Mobil 1 75W-90 gear lube. Should take a bit under 2 jugs. Don't fill it past the add plug, otherwise it just starts to fill up the tubes instead of staying in the pumpkin, and leaks out the axle seals.

 

Ok used all the old parts and it went right in and rotates fine and now another question ...how do I refill the rearend?

 

Remove plug, install fluid, reinstall plug.

 

http://www.nastyz28.com/forum/showthread.php?t=19773
Read this and see if you can get the Auburn in and working correctly.

 

****UPDATE*****
Ok so after i finally took the time to refill my rear end it was a success!!no weird noises no grinds, chatter or anything and both tires burn down the road thanks for all the help from everyone here