72 chevelle,408 bb.I just purchased a rebuilt 12 bolt w/eaton posi,i was told by the guy to use 90 weight gear oil,so i got 90 lucas gear,i broke in gently,it makes rowdy noises when i turn,not straight.I put on jacks,spun in gear,no noise,clutches breaking in?,little over 100 miles or so.

Did you use any posi lube?

It is an additive you need to add.

Many guys will say to use only GM limited slip additive.
With my Eaton unit I used Motive Gear brand.

no i was not aware of that,what should i get

my truck made the noise while turning. Changed the fluid and added the GM posi additive, then when and did stop to stop turns in the mall parking lot. The mechanic said I needed to get the additive between the clutch plates and such. After 10 circles in each direction, I never heard the noise again.

Go to the chevy dealer and get some GM positraction fluid and add it. I have an Eaton Posi in my SS and I love it!

Chuck

Chattering-rattling-popping, ares somewhat common noises associated with posi units. Usually, adding a bottle (they're very small bottles) will eliminate the noises.

When I had my Eaton posi. unit installed my mechanic told me to use GM positraction additive and 90 weight. He also told me to put the rear of the car on jackstands and run it in gear for 20 minutes before actually driving the car. He is an excellent old school mechanic that does any work I can't do, and has never steered me wrong. No problems with rear-end in last two years.

GM POSI additive is GM#1052358. Any GM dealer should have this. Should cost you about $7.65 for a 4oz bottle.