was driving with my dad, and for some fun, launched off a light, when we drove back through, we noticed, there was a small mark, but only one, which led me to beleive, something may be wrong with my posi, so my dad, got out at my house, and asked me to brake toruqe, and afterwards, there was still only one mark, is it my posi, or something i am unaware of

 

It's possible. Do you have a 9-bolt rear in your car or have you physically looked at your rear and known for sure it's a posi (stupid question, I know, but I have to ask)? Have you or anyone else changed the fluid in it without adding GM posi additive by any chance?

 

How sure are you you havea posi? Have you physically seen the posi unit in your rear?

 

The limited slip additive is just a friction modifier. It makes the 80-90 slicker so that you don't get chatter or binding around corners. If it wasn't there the limited slip would still function ok.

If you are positive you have limited slip, the clutches are worn out. Get new clutches and spring, clean diff out real good, install the new clutches, and your good to go.

 

This is an 82, not very many 82's had posi. So its really not likely have posi. Have you taken off the cover and seen. Did it look like this?

 

nothing back there has been changed, but im not a car pro by any means.... so im guessing its a 9 bolt.....

 

The 9-bolt was not introduced until 85.

If it's a 82 car, and nothing's been changed, it's a 10-bolt; and most likely not a posi (there being very very few of them in the early years, as mentioned), but the only way to know for certain is to take off the cover and look.

Lack of posi additive would not prevent a posi from working, if it has one; it would only cause it to chatter and groan going around corners.

 

The rear currently in my car came from an '82, and is a posi. But, I know that because I've had the cover off and verified that it looks like the photo posted above.

No need for the "posi additive", as I use AMSOIL Series 2000 75W-90, which already has it in it.

 

so what would my solution to this problem be? posi additive? i stil confused, it seems as if only the left rear is grabbing, and i have no grip coming out of the right rear, only spins and im forced to let off, because i am afriad to mess up my baby

 

Step 1:

Open up the rear and see if it's a posi.


All else is spank-off and a wate of time. All the talk about additive in the world, will do no good whatsoever, if it's not a posi (as it most likely isn't).

 

All the posi additive does is allow the clutch plates to slip against each other more smoothly during cornering. It does not make the posi "work".

If the posi doesn't work w/o the additive, it isn't going to work with the additive. If the posi chatters in corners w/o the additive, it shouldn't chatter in corners with the additive.

But like RB said, none of this matters until you know whether or not the carrier in your rear end is a posi unit.

 

Yeah, disregard my comment about the posi additive, I wasn't thinking about what I was saying at the time.

 

ok, i do not have a posi..... so im still confused as to what is going on, after this problem is fixed, what kind of figures would i be looking at for buying a posi, and the difficulty of installation

 

I'm confused about what you're confused about... sounds like your rear is working normally. Nothing to fix.

All you need is a posi carrier, of the appropriate series for your gears; which would be either a 2-series (3.08 or numerically lower) or 3.23 or numerically higher. The carrier would have to have side gears with the same splines as your axles, which is 26; 88-back had 26, 90-up have 28.

So while you have the cover off, count the teeth on the ring & pinion, or look at the edge of the ring for the ratio to be stamped there; you might see 40/13 for example, which is 3.08 (3.076923076923...). Order yourself the posi of your choice, such as Eaton, Auburn, etc. and a set of carrier bearings.

 

Your car didnt come with a posi differential, they are not standard issue.

If you want a posi differential then you'll have to install one. they arent cheap, your best bet is to go to a junkyard, and check all the 3rd (or even 4th gen if you wanted) differentials for one with a posi. I dont think that any 4th gens came stock with a posi though, maybe the SS and Trans Am though, I'm no 4th gen expert either.

 

LOTS of fourth gens came stock with posi rear ends.

 

I didn't realise a 3.08 was a 2 series diff. My 83 has a 3.08 posi, as verified by inspection, but isn't there an rpo code for posi? I also seem to remember that if you jack the rear up and rotate one wheel the opposite wheel will turn the other direction?? Been a while since I tried this, so I could be off beam ;-)

 

Yes there is a "code" for posi. However the "code" doesn't get changed when the parts get changed; so the only way to know for sure that you have it or not, is to look. For example, my car doesn't have the code, but it definitely has the parts.

Posi consists of a clutch pack that forces the axles to rotate together. The clutches require a certain amount of torque to overcome this. The breakawy torque for the stock posi in one of these cars is in the 50-60 ft-lbs neighborhood. Therefore, if you put the car in park (or in low gear if it's a stick shift), jack up the rear, spin one tire, and it doesn't take about 100 ft-lbs to turn it while the other tire spins the opposite way, it is a certain indication that you don't have a functional posi. But even then, the car might have been equipped with it, it's just worn out.

A 4th gen carrier won't swap into a 82 car, unless you change the axles to 90-92 ones with 28 splines. And of course, the enormous majority of the 4th gen ones are 3 series; and it's not possible to use a 3 series carrier in a rear, without putting a 3 series gear ratio in it.

 

I've had very good luck with these guys, they also have a wide selection in both type and costs.
http://reiderracing.com/differentials.htm
This should give you some options, I'm currently running and Auburn gear posi with a 4.11 gear. and am very happy with it.

 

Posi code is G80, if I remember right.

Actually, very many 4th gens came with 2.73s rears. I thought the opposite until I bought mine, found out it was a 2.73 (thought it was a 3.23), and did some more research.

2.73 is actually the standard gear ratio for all automatics, with 3.23 being an option. This is even so on the Trans Ams. My rear came out of a '98 TA convertible and is only a 2.73

3.42 though, is of course, the standard ratio for manuals.