I put my 87 camaro up on blocks today, and i turned the Drum brakes in the back, and the other drum brake turned the opposite way. I had my friend hold the other side, while i turned mine, and the same thing happened. Does this mean i have a limited slip rear end, or possibly posi?
Thanks

 

When one wheel turns forward and the other turns backward you have an open differential. You could still have a locking diff (Gov-lock). It will lock the diff when one wheels starts to spin but you can't do it by spinning the wheels by hand.

If you turn one wheel forward and the other also turns forward then it's a true posi. The clutches hold the spiders allowing both to turn at the same speed. When you go around a corner, friction allows one wheel to turn faster than the other overcoming the friction of the clutches.

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Usually, that indicates that you have an open rear (peg-leg), however, you could have a posi, and the clutches are burnt alowing them to slip, even w/ the pre-load springs (like Stephen touched apon), but a burnt posi is as worthless as an open rear, so you may as well say its an open.

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was the car in nuetral(sp?)if both tires spin in the same direction you have posi. if you spin the tire and the driveshaft spins OR the other tire spins in the OPPSIDE(sp?)direction you have an open rear hope I cleared some confusion up.