I'm sorry, what? There is no rapid disengagement, or really any engage/disengage action in a posi rearend.

 

Clutch packs are given constant spring pressure to keep both axles rotating at the same speed. If the difference in traction is enough to overcome the holding force of the clutch packs, the diff will slip. If there is not enough force, it won't. The spring pressure doesn't change or release.

 

Perhaps you are thinking of a locking rearend? Those would function like you are describing. But locking rearends don't need limited slip additive. Nor do Torsen rearends, which function with a worm gear. The additive is only needed in limited slip rearends that employ clutch packs.

 

The chatter happens because the clutch binds, then gives and then binds again instead of having a smooth action, not unlike what happens with torque bind.

 

i was taught that at the preset speed differnce between wheels (from turns) that the clutches released, maybe im thinking of the cone type. Torsion is an entirely differnt animal. ALso its been ages since i have opened one up. i'll have to go back and re read it

 

nipper

i was taught that at the preset speed differnce between wheels (from turns) that the clutches released, maybe im thinking of the cone type. Torsion is an entirely differnt animal. ALso its been ages since i have opened one up. i'll have to go back and re read it

 

nipper

 

They don't release, its just the torque difference generated by the wheels spinning at 2 speeds on normal pavement is enough to overcome the clutch pressure.

 

This makes a positraction rear end suck somewhat on snow and ice, because the wheel doesn't unlock in turns when both wheels have low traction, which will commonly fishtail the rearend.