I had an Eaton posi installed in my 10.5 Differential. Its quiet driving around localy. But after I have been on the freeway and get off and hit the city streets again the rear makes a lot of noise around corners. The first time I come to a stop and have to turn the car will actually shake a bit. Or if I have to back up I hear weird noises. After a few turns it quiets down again unitl the next time I drive a distance without many turns particularly the freeway. Is this normal? Do I need more posi additive? And if I do add more additive, is it posible to add too much and is this bad?
Thanks!

If you have an automatic tranny, check the fluid level, I had the samething happen to me and I swore it was the posi part of the rearend making the noise. I pulled the cover, inspected it and refilled the rearend, still made noise. Then I check my tranny fluid and it was a pint to 3/4 of a quart low and after I topped it off the noise went away.

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70 Camaro Sport Coupe 350cid balanced, blue printed and running smooth. The 70 (http://camaroz28.cardomain.com/id/joekoul)
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Sounds like you don't have enough posi additive and the clutches are "grabbing" once everything's warmed up fully.

Can you use too much additive? I'm sure you can- it's not gear oil after all. Alot of people suggest using 2 bottles of additive with a fluid change, even though typically one bottle "should" do it.

The 10.5 rear end holds more oil than the car rear ends, so you may need more than one bottle of additive. I use Amsoil 75W90 Series 2000 in the posi rear ends that I build. It handles heat much better than petroleum oil and doesn't need any additive. You may want to use a 75W140 in the big truck rear end.

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'69 RS/SS396 Pro Street
427 4 speed 9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

Thanks guys,
I think I'll try adding a bit more additive and next time I change the fluid I'll use tha Amsoil.

I always throw 2 bottles in my posi - SUPER QUIET.

Too much additive can keep the clutches from locking up when you want them to.

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'69 RS/SS396 Pro Street
427 4 speed 9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)