maro323

Hey tgo peeps. I have an 89 rs wich has the cheap rear end non posi. I found in a ju.k yard a iroc tpi with posi drums. I would like to know if its worth the swap. Ive seareched but I have little understanding to it. I know im expecting the "search" bar. But any info would be greatfully appreciated

padak

iTrader: (10)

Well, non-posi to posi is a plus, also depends on the gears and if you want drum or disc brakes.

I will say most people opt for the posi rears with disc brakes.

Base91

iTrader: (1)

Depends on how much work you want to do or how much you want to spend. Going to posi is great if you don't want to spin one wheel but most of the ju posi rears are worn out or near to it so you may need to replace/rebuild. As for drums they brake just as well as discs pretty much but fade quicker. Depends on what you want to do with the car. Also, you could swap on discs but time and money.

AlkyIROC

I agree. A junkyard posi might seem like a good find but it's probably also worn out and it will be cheaper to just buy a new posi especially if your diff already has disk brakes.

Using a junkyard posi is still better than an open diff but don't expect it to be in good condition or for it to last very long. They all wear out.

big gear head

What gear ratio do you have now? This is very important to know. If you are looking for another rear end and it has a different gear ratio then your speedometer will be off and it might make your car slower. If you decide to install a new limited slip differential in the rear end that you have then you MUST know what gears you have before you can order the new differential. If you have 3.08 to 2.41 then you will need a 2 series. If you have 3.23 to 4.56 then you will need a 3 series.

I would recommend installing the new limited slip differential in the rear end that you have now. There is a very good chance that a rear end that you find will have a worn out limited slip, or almost worn out. The Auburn that was used in these cars can not be rebuilt, so it would be a total waste of time and money.

Eric-86sc

iTrader: (18)

Depends on the cost. If the junkyard only wants $200 or less and it is a desirable ratio (3:23 or higher), I'd say its worth taking a chance on the posi being good. The drum brakes aren't a big deal as the iron calipers that would have been on the car if it had disks are not that great.. If your worried about the posi being dead there are tests you can do to measure how strong it still is (or isn't).

maro323

Well mine is an rs idk the.gears.and also my car is drums and well I just wanted to get a posi for it to run on both tires. Disk I would prefer but I dont have $....

maro323

Tje reason I want a posi is to run on both tires. But now that you mention about wear on the diff. Well ima think about it twice

maro323

Well you convinced me to just wait and buy a new diff....

maro323

Well idk the.gear ratio. And I was told that the axles would fix the spedomeeter. But idt ima do the swap it sounds like to much of a hassle

maro323

Well with all this info everyone gave me......ille stick with my diff and make.it a limited slip f***k it. Thanx for the.help guys

RedLeader289

iTrader: (2)

limited slip and posi are the same thing. Posi-trac is just a fancy term GM coined for their system. just an fyi

big gear head

Axles will not fix the speedometer. The way that you fix the speedometer is by changing the plastic gears in the transmission that drive the speedometer cable.

If the rear end in your car is original then you can find out what the gears are by checking the RPO sticker on the bottom of the console lid or on the back of the spare tire cover. It will have a bunch of 3 digit codes on it in alphabetical order. The G codes are the codes for the rear end. It will be something like GU4, GU5, GU6, GT4... This will tell you what the gear ratio is. If someone has swapped rear ends then the only way to find out what the gear ratio is would be to remove the cover and count the teeth on the ring gear and pinion gear and divide.