I bought a rearend out of a 1999 Trans AM so I could have posi track on my firebird, but when I took it to my mechanic he told me that it diden't have posi track because whrn you turn one side the other side turned the opposite way.

but when you turn the yoke both sides turn the same way.

But, when you grab ahold of one side while you turn the yoke the side you grab would hardly give any resistance and the other side keeps turning the same way freely.

I would just like to know if I got ripped off on this rearend or not. upon opening the cover on the rearend there is a posi track box inside there.

any help on this topic would be greatly appreciated, this is my first dealing with a positrack unit.

also it is going on my 1999 firebird, I figure it should bolt right up. but if anyone knows of a problem with this feel free to chime in.

 

If you bought the stock rearend out of the Trans Am, then I'm 99% sure it has posi. I don't know much about rearends, but I think your mechanic may be mistaken.

 

they are limited slip.. not really a true posi... works just the same

 

what is the difference between limited slip and posi?

 

In my opinion, the limited slip differential is better. Especially for my daily driver. Posi's always spin both tires no matter what so sometimes they are harder to control. On a limited slip differential like yours, one wheel can slip and the other can still retain traction. You didn't get ripped off.

 

they are both the same! posi is GM's name for a limited slip diff.

other names for limited slip is sure-grip (chrysler), equal lock, those are the most common, But i've heard people say other names. man an easy way to find out pull the cover off and look for a set of disks,(clutch pack) they are behind both side gears. looks like a whole bunch of disks all packed together.

remember just because it's limited slip dosen't mean your wheels will turn together all the time, those friction disks are made to "slip" also to allow one wheel to spin faster than the other, during cornering or what not. They have a spring tension to keep the clucthes engaged and both wheels spinning. the only time you can be 100% sure that both wheels are going is under high torque situations. do a burn out and look for two tire patch marks
then you'll know

btw when u say u grab a hold of one wheel and put resistance to it, and the other wheel just spins freely, that is lsd. the wheel with the most traction (one you are putting resistance on) is gonna receive most of the torque , while the other one will just at a slower rate.

 

the reason it turns the opposite way is because it's not a clutch type limited slip. only the clutch type's or true lockers hold still. the torsen works alot like a gov-lock which will also turn like an open diff until torque is applied. if you pull the cover off, you'll find a torsen in there which will work the same pretty much as the auburn does in the older models.

 

ya u didnt get ripped off so its all good......

 

how come when i pulled my cover off i saw a clutch pack??

 

because you have a 98. they switched to torsens as standard in 99. in 98 all Z's and standard T/A's and Formulas came with an auburn clutch type.

 

From what i have read and seen it is called a open end posi, it will grab when you are stright but when you turn it will give on one of the wheels so it can turn better..Mine does the same thing I noticed it when I helped a friend put in a locker. When I hit the gas I will lay two solid black marks

 

The torsen is a gear type torque sensing limited slip differential. It senses the torque difference applied to each drive axle. It has to be a significant difference. This differs from standard limited slip differentials in that they are a preloaded clutch type. They have different springs that increase the preload on the clutches. That is why your limited slip seems broken.

 

Here a pic of both types:
Zexel Torsion
Auburn Type

 

No mater what they name them, they are all "LIMITED SLIP".