I searched all over the archives and i can only come up with people who change to posi and change the gear ratio as well

well my question is can i swap a posi into my open one wheeled trans am without changing the gear ratio/ can i simply unbolt the bell housing, take out old differential and put new one in??
thanx Bill

 

Bill,

You answer is yes, and no depending on what posi you want to go with. First, what rear end do you have? 9 or 10 bolt? What gear ratio do you have, and what spline axles are in your car?

I'm going to comment on a 10 bolt rear application because that's what I know. If you have a 88 or older car then you have 26 spline axles. If you want to go with a $99 zexel from SLP, then you have to swap your axles out to 28 1990 and newer axles. Also, a zexel is a "3" series carrier meaning that it will work with 3.23, 3.42, and 3.73 gears. I will not work with 2.73 or 3.08 gears.

If you have an 88 or older car and want to use the gears you have and not swap them or the axles, you can get an eaton or auburn pro posi that will work with either 2 or 3 series gears and 26 spline axles. The posi is about $350 I beleive.

So to use a zexel if you have the correct gears in the rear end now, you add up the cost of 28 spline axles (about $100 I've heard-might get them cheaper if you look around), add the zexel with shipping for $113, then new carrier bearings for $50, a adjustable shim pack for $30, new axle seals for $10, gear oil $10 you are at around $315. If you can do the work yourself then other than needing a dial indicator and mag base for another $20, that puts the zexel at around $345.

If you went with the eaton or auburn ($350) you would still need the bearings for $50, shim pack for $30, axle seals $10, gear oil $10, and dial indictaor and mag base for $20. So that puts the eaton at around $460.

It will take exactly the same amount of time to install either the eaton, auburn, or zexel if you have to pay to have this done.

Hopefully I've made this clear as mud to you If you don't understand what I've written, feel free to email me and I'll be happy to try and explain further.

 

i understand everything and almost always do my own work.. my car is 88 and i believe it has the 2.73's because "i think" due to the fact some *** hole (previous owner)decided the rpo code list was unimportant and ripped it off
its a trans am 305 Lo3, I would love to change the axles and all that other expensive time consuming stuff but i dont have the cash or the time so i'll have to find a way to get a cheap posi with 26 spline axels that fits the 2.73 gears if i understood you correctly.. and all of the other things to do the swap! thanx for the info ! i will use it wisly!
Bill

 

You can re-use your gears, but due to manufacturing tolerances in housings and carriers, you will still have to "re-setup" the ring gear (you won't touch the pinion, its depth won't change). You will have to find the appropriate amount of preload and backlash. You might get lucky and the old shims will fit perfect, but if it was my personal ride, I'd start over and eliminate any "guesswork".

 

intresting... since i know didly about gears, i might have to read more on this... i was kinda hoping i could just slide the new part right on in! haha
i guess posi wont be that easy

 

i think u can weld the spider gears to get the posi effect but once that weld breaks there is no more rearend. if me remembers correctly. which i havent been doing lately

 

Welding the spider gears is probably the most "anti-streetable" mod you can do to your rearend, certainly not reccomended.

 

Bill, would you be interested in a used 26-spline factory posi? I upgraded the rear in my 89 IROC to 28-spline. The posi has 50k on it and is tight(both wheels will spin). Also has new side bearings on the carrier. Could save you some money if your interested. You can e-mail me at ZZ405@webtv.net