im wondering if my car is posi, its a 89 trans am with a 305 and 700r4 trans, i did a couple burnouts and 3 times it was two wheels and the others were one.

 

o sweet it gives all my cars info on the side, just i typed that stuff for nothin, lol

 

So was it posi or not? Right now I have a non-posi rear but it spins both while powerbreaking.

Next week I will have my 3.73s and stuff in. I'm excited.

 

sounds like a posi that is wearing out.


G80
AXLE POSITRACTION, LIMITED SLIP, 28 spline


look for that rpo code, G80

 

pull the cover and look, it's the only 100% accurate way to know.

 

What ede said. All of that crap about 2 tires is just that, crap.

I'd almost be willing to bet money the car didn't come with it; but who knows what it's got now, without pulling the cover.

 

lol thats a sweet smiley.

anyways its stock so it would be watever it came with.

whats a RPO code?

 

how do you know it's stock?

rpo is production order or what the car was built with

 

my whole car is stock, wat the guy i bought it from said.

 

That's what they all say; except when they tell you it's a 350, or "from a Vette", or "police interceptor". All that means is, he hadn't changed anything he was willing to admit to. Who knows what some other PO might have done to it, or what it might have needed under warranty, or whatever.

Takw off the cover and look. It's the only way to know for sure.

 

If you put your hand on the differential cover after you drive around for a bit and it feels warm, thats posi-energy emminating from the posi unit.. If its cold, then its an open rear..

Well, kidding aside, pull the cover and look because you probably need to change the fluid that is back there anyway, and you could kill two birds with one stone...

 

i heard that if you turn one wheel one way and if the other rotates the other then you have a posi...is that right?

 

No, that is exactly wrong. That's EXACTLY what a posi is intended to fix.

The most common kinds, like the one in my pic, uses clutches to connect the axles to the carrier, such that in order to make the axle rotate at any speed other than the carrier's, enough torque has to be applied to overcome the clutch. That's typically in the 50-90 ft-lbs neighborhood for various models of car rear ends, for each axle.

The thing about the wheels spinning in opposite directions is what happens when you take a non-posi rear, and hold the carrier still. Under those conditions, rotating one wheel will make the other rotate at the same speed but in the opposite direction; and it takes virtually zero torque to do so.

 

damn...thanks for letting me know!

 

You could crawl under the rear and if you see a tag on the differential under one of the bolts then its posi, or if you could jack the rear off the ground safely and put it in drive and if both wheels spin then its posi if only one wheel spins its an open rear

 

So what do you all call it. Posi or limited slip. The correct term is limited slip is it not?

 

call it either one..

no difference and both are common terms.

 

I seriously doubt it came with posi. Probably the usual 10 bolt with drum brakes and 2.73 rear gear ratio that comes with most of the tbi cars. Not really necessary with only around 250 ft-lbs of torque from the L03, well, except in the wintertime when its snowing.