Narcah

Is this a sign my posi is dead? I've had this problem for about a year, first time I knew was at the dragstrip. When I do a brakestand, only the right spins. I recently changed the differential fluid with some good stuff, and it still happens.

Is there any other solution other than my posi is dead (2.73, 85k miles on it)?

Thanks.

klumb15

its hard to say...i'd say its on its last leg...sometimes with really high gears, like 2.73's, a crappy posi unit will do a one wheel wonder for some odd reason...but usually that is what posi does when its shot....time for a new one...

sw89lt1

what 3rd gens came with a posi? i don't think my car has one. if it does it never worked.

Narcah

Mine for sure had posi (aka, limited slip) but I have a feeling its dying.

klumb15

thast wierd that it came with 2.73's and posi....usually they give you 3.08's or lower when you get limited slip...

Narcah

Next question would be: Since I want to upgrade to 3.23's (good balance in my opinion) would it be better to find a third gen rear in a junk yard (possibly have bad lsd) or find a 4th gen rear?

mako350Z28

A 4th gen would certainly be easier. When my rear end went out, it took a week to find one for my car (G92, posi, 3.23's, ect...), and then there were only 4 or so east of the Mississippi River. I just decided to go with a 12 bolt Moser instead.

klumb15

i'd go with a 4th gen..get one that came outta a 6 speed....3.42's came in those...and those are great all around gears...

Blue89Bird

if you put a 4th gen rear in your car, youre going to need to run 4th gen offset wheels

Narcah

I understand that you can run 3rd gen wheels on a 4th gen rear, they just stick out an extra inch or so? Right or wrong?

klumb15

2 inches actually...i'm not sure if its 2 inches each side, or if its split..

iansane

They stick out 2" either side; from the stock location. Which doesn't mean 2" outside the fenders. It's only about 1" or so.

CrazyHawaiian

Depending on what type of rearend it is, there might be a test you can do to see if the posi is still good or not. Do you know if its a 9bolt or a 10bolt rearend? I got a 9bolt and I used this procedure from www.9bolt.com to test my posi: http://koolenterprises.com/diff_sol/posi_test.html and my posi was still good. Did the burnout test and I still get 2 lines, so it checked out.

If you have a 9bolt and the posi is bad you're looking at an expensive replacement posi unit. 9bolt parts are extremely expensive compared to 10bolt parts. So if this is the case, consider a 10bolt replacement, or another 9bolt from the yard but make sure to test it. Now if you already have a 10bolt there are a few things to consider. Pre 91-92 10bolts had 26 spine axles. The 91-92's had 28 spline axles. 4thgen's use 28 spline axles. So if you can find 28 spline axles from a 91-92 10bolt from a 3rd gen, then you can use a posi differential from the 4th gen rearend. Since those usually have lower miles, they are more likely to be good. I got a rearend from a '00 SS for fairly cheap, going to be using the posi and LS1 disc brakes on my stock 10bolt w/ drums from my 91Z28 w/ 28 spline axles. Cheap fix, but wouldnt have been too smooth with an earlier 10bolt with 26 spline axles. I also went this route to retain the stock rearend wheel specs. I wouldnt do the complete 4th gen swap unless I planned to run 4th gen wheels (with adapters in the front only).

87DJP2001

No 3rd Gen car came stock with a Limited Slip (aka posi) it was a extra cost option. RPO G80 is for a Limited Slip and on certain cars it was required but you still paid extra for it.
It could be had with any stock gear ratios if special ordered.

mako350Z28

.


It may be an option but it was still stock, as in came from the factory. Mine was included with the G92 package which was mandatory with the 350.