Alright so I've been wanting a POSI unit on my z28 but Im not very knowledgeable on as to what exactly I need....Right now I have stock NON posi gears which I believe are 2.73. So in in other words what exactly do I need to get something like 3.42 gears. My car is a daily driver and some track days/racing. What do you guys recommend.

 

First what rear end do you have? 9 bolt or 10 bolt? From the ration it sounds like 10 but count the cover bolts to be sure. The absolute easiest way is to get another rear end with what you want. If you want to do it yourself there are many threads on how to do it. I'm in the last stages of rebuilding a 9 bolt for the first time. Plus adding 1LE brakes. Read a lot first.

 

Yeah I bet...I beleive I do have a 10 bolt...if I remember correctly...well the other month I saw a bird with a posi unit on it....i didnt check the gear ratio but now I regret graving it....how hard is it to install a rear end..

 

If you replace the whole thing with the same type but with the parts you want then jack up the rear and unbolt/unscrew what you need to and reverse with the replacement. You just need to get the car high enough and be able to lower the axle in a controlled way. Be careful the springs are all the way extended before you try to pull them out. There may be issues with the brake lines and park brake cable depending on what replacement you use. If you want to just install a posi unit in your current axle then google and you'll find a few. Plus plenty of write ups here on which to use and how to do it.

 

I think the second option might be a little easier...woudl you happen to know how much they usually run?

 

It's a while since I researched but low was mid $300 to about $600 depending on which and where you get it. There is plenty of opinion about the various types/makes. Essentially take the cover off, drain the oil, take the axles out, remove the carrier and put in the posi unit and replace everything. But easier said than done. There's likely to be some careful set up to make sure the unit and the gears are adjusted correctly. There would be instructions with the unit and on the board about doing it all. In the end I went with a 9 bolt to rebuild and replace my 10 bolt. That way I could still use the car. When I get the 9 bolt in I may upgrade the 10 bolt to posi and I have another set of 1LE brakes and brackets for the 10 bolt.

 

http://www.nastyz28.com/forum/showthread.php?t=19773
To install a limited slip differential (posi) and use the same gears that you have now. You will need a 2 series for those gears.
https://www.thirdgen.org/forums/tran...axle-gear.html
To change the gears at the same time.
https://www.thirdgen.org/forums/tran...-10-bolts.html
You will find the answers to most of your questions here.

 

I'd suggest you find another 10 bolt with the gear you want. 3.23 is a nice all round ratio and gets you to series 3 carrier. If you can get one with posi good if not you can do the changes then just swap them. That way your car isn't out of action for a long period. If you know what you're doing the posi could be swapped in a day but first time?

 

If you don't want to spend allot of money than finding a complete rear end really is your only choice. Or..... you can do what I did and buy better new parts. What ever you end up doing IMO it is well worth the time, effort ,and money because it makes a "huge" difference in the way the car preforms and is a must do modification.

$700.00 for master bearing kit , axle bearings and seals, 28 spline axles, including 3.42 ring and pinion, and labor ,$535.00 for Eaton 28 spline Posi.,$169.00 for LPW Ultimate support cover.Total = $ 1,380.00 .With a 3 year warranty on parts and labor.

 

dam that looks sick....I think for now Ima keep an eye out or posi units in the junkyard and if worst comes to worst Ill just end up buying all of the pieces myself.