Just saw my 86 IROC has an RPO code of "G80" which this sitetells you is positraction. Without sounding like I need to watch "My Cousin Vinny" again, what capabilities does that give the car?

traction to both rear wheels instead of just one like a non posi car would have.

Both wheels will spin rather than just 1 like in an open differential. Or in layman's terms, you'll lay down two stripes...

Spins both rear wheels. Adds up to better straight line acceleration, and better in the rain too! (because you don't lose as much out of the hole)

"What is positraction?"

"It's a limited slip differential, which applies power equally to both the right and left rear tires. The Buick Skylark had a regular differential, which as anyone who's ever been stuck in the mud in Alabama can tell you, one tire spins, the other does nothin'."

A regular differential sends power to the wheel with the least amount of traction, but a positraction sends power equally to both tires, unless there is a difference in wheelspeed, like when going around a corner, and then the clutches slip and allow one wheel to turn faster than the other one. Otherwise the car would jerk as you turned a corner.

Positraction is a more desireable option because of the increase in performance (better traction off the line since the power is split between two wheels instead of all funneling through the one wheel with the least amount of grip).

How Stuff Works Dot Com

Check it out. They have a section on differentials with some helpful animated illustrations. You can get at least a basic explanation of just about any automotive component or system on that site.

JC

Hey, I like "My Cousin Vinny"!

JamesC

It's a fantastic movie.