lee33lyn

iTrader: (3)

I heard that if you jacked up the rear of your car and spun the tire, and both tires rotated the same direction,then it had a posi rear. Is that true?

9000th01ss

iTrader: (10)

Thats true with most types of posi differentials. But a torque biasing diff like a factory installed Torsen will act just like an open diff while spinning the tires with it jacked up.

lee33lyn

iTrader: (3)

so how do i tell what equipment is in my 95z28? the code says 3.42 gearing,but I think its been worked on. I just bought the car about a month and seen a receipt in the dash for rearend work. I've got the cover off to change the oil but I don't know what I looking at.
thanks Lee

Badazz 97 TA

iTrader: (18)

do a burnout.....?????

nighthawk15

LS1 or LT1 car? The LT1 cars only ever came with Posis except for a some SLP (SSs and such) cars IIRC. Pretty sure the dif cover looks different on the Torsen cars too.

EDIT: pic of a Torsen on a 96SS

lee33lyn

iTrader: (3)

Its an Lt1 car.My rear end cover is the simple smooth painted one.

9000th01ss

iTrader: (10)

Both my 01 Z28, and 02 SS have Torsens with steel covers.
I attached some pics of a Torsen diff out of a 2000 SS.
This here is some kind of open diff I found with google, same thing yours will look like if it's an open diff.

nighthawk15

Its a posi then unless somebody changed it.

lee33lyn

iTrader: (3)

I'm gonna change the fluid in it. Should I use the gm additive for posi?I can see springs in the center of my carrier,if that helps.

streetassasin

iTrader: (30)

Check the door jam for G80, its the rpo for a posi

9000th01ss

iTrader: (10)

If you see springs then it's an Auburn posi. Assuming it's the factory installed one, Auburn isn't the only type with springs.

You need GM additive, Auburns will make noise wwith the cheap parts store type that comes in a tube.

9000th01ss

iTrader: (10)

I think if this person has the cover off, it should be obvious what it is by looking at it, they said it has springs. It is a posi.

lee33lyn

iTrader: (3)

Well, the thing that confuses me is that when i bought it I did a burnout with a buddy behind me and both wheels spun. Later, I did it again and only one wheel spun.I'm new to the 4th gen and don't know what all they came with.Just looked and there is a gu6 and a g80 in the glove box.

9000th01ss

iTrader: (10)

What year car is this?

Nevermind is a 1995, seems like a posi doing one wheel burnouts in a '95 might be worn out.

nighthawk15

^This^

It happens to every posi at one point or another. It's just the nature of the design.

lee33lyn

iTrader: (3)

there's a receipt in the glove box for a rearend replacement only a few months before I bought the car,but there's no details about it,just cost.

9000th01ss

iTrader: (10)

Does it say where the rear came from?

You have a clutch type posi rear. There are tests you can do to see if it's worn. For example, jack one tire up, put it in neutral, see how much torque it takes to turn the wheel in the air (this measures clutch slip).

The preload springs are only there to give you 'preload' This is a push on the clutches to provide resistance at rest.
What really locks a posi is the upset force when you have decent grip on both tires and you accelerate hard, the gears (in the posi) try to seperate. This seperation force pushes the side gears against the clutches and locks them.

You can google a lot to find info. Like Google Auburn and read their website.
Google limited slip theory, etc.

I don't know how good a teacher I am, but reading it right off the manufacturers website gives you a sense of seeing correct info vs some random persons info.

lee33lyn

iTrader: (3)

I think they replaced the ring and pinion (spelling?)only,not the carrier. I can see the scars on outside of the carrier from the ring gear coming apart.I've put several hundred miles on the car and the rear seems fine.I'm redoing the fluids,bushings,brakes getting ready for my first HPDE at VIR in a couple weeks.