I bought a posi unit out of a junked 87 z28 with 3.08 gears. I laid it on my garage floor, slid the axles in, put the big pin back in and then using a crowbar on each axle, I tried to turn each axle in different directions. It wasn't easy - I had to lever pretty hard but I did get them to go in opposite directions. I don't know if this is normal or does it mean that the posi is worn out?

 

I'm certainly no expert ... but from what I read/understand

The posi works with pressures, and I'm not sure you can 'duplicate' those pressures on the garage floor, but it kinda sounds like you did, just not in the way you thought it would work.

Posi doesn't always mean it's locked. A 'locker' locks the two axles always - just as though they were welded together. A 'posi' is a Limited Slip - meaning it does allow slippage on a limited basis. Like in a tight turn, the outer wheel HAS to turn faster than the inner wheel - it has more distance to cover in the same amount of time - so the unit has to allow it to slip. When a locker is in place, you get a "chunking" feeling, because the inner wheel has to spin at the same rate as the outer (they are locked), and thus the inner wheel spins, but it's getting traction on the pavement, and so this attempt to spin makes the wheel hop and thus the 'chunk' feeling. That's why older locking 4wd units (like in my old Bronco II) have to be 'turned on and off' - you can't use a 'locked' unit on the street unless there is a slippery substance to allow that inner wheel to slip on the pavement (like snow).

That's why lockers are a no-no on a street car - they'll break from the stress, or something will break, like the axle or something, since that inner wheel can't spin and thus hops. Locker units are great for the track I guess - no wondering if the pressure built itself up enough to kick in the limited slip in time to get your power on the pavement without costing precious 100ths of a second. And great for real 4wd apps, you turn them on/off when needed (like the hub locks on my old Bronco II).

But on the street, you need a unit that will allow some slippage (tight turn) and will lock when allowable (straight stretch).

Sorry - I babbled - but you get the idea - bottom line is a 'posi' unit has to slip some - thus 'limited slip' - you might have just been able to pry enough to allow it to slip. Hope that makes sense. My guess is that your unit is fine - you just exerted enough pressure to allow it to slip, which it's intended to do.

 

Thanks. It's nice to know I didn't waste my money and time on the posi.

 

Yea, it's still good. If it was worn out you would be able to turn it easy.