I was told to get Posi before dropping a 350 into my camaro. I have an 86 Berlinetta. How do i know what one to get? How much should I be looking to spend? How hard is the swap? And is there any one to stay away from?

 

really...noone knows or wants to share this info? Or point me in some direction please on how to find out.

 

Its not a required upgrade or anything, but it wouldnt be a bad idea. All 'posi' (positraction) is, is a limited slip differential. I.E. the differential has an extra mechanism inside it that prevents one axle from turning much faster than the other. On a non-posi or 'open' rear, if one tire loses traction, all the power is transferred to that tire because it is now the easiest to turn. This means no moving forward With a posi differential, even if one tire loses traction, the other tire is still pusing the car forward. If you burn out with an open diff, you'll leave one tire mark, posi you'll leave 2. It is possible to swap in a limited slip differential, but you have to completely disassemble the rear end, which means taking off brakes and pulling out the axles. It would probably be easier to find a whole posi rear from a junkyard. Some thirdgens came factory with them, it was just an option. My 83 firebird came with one, even though its not a trans am. However, I would look at Z28's, IROCs, GTA's, Trans Ams, etc for them. Don't bother looking at baseline six cylinder cars, they're probably not gonna have them. The only real way I know to check is to unbolt the differential cover, and see if there is a posi unit inside or not. Maybe someone can post pics of what both types look like.

SLP sells take-off posi differential units for $99. These are removed from brand new Z28's that are turned into SS's and replaced with better units. Since the units have a couple miles on them, they can't be sold as new, which is why they're $99. Fourth gen camaros/firebirds use the same rear end as third gens, so the differential will bolt in. I am not sure of the details on how to do it though, or if it can even be done at home. I'm also pretty sure that the units will only fit 89 and up rear ends, because they are slightly different, with a 7.625" ring gear instead of a 7.5" There are also different spline count axles which were used, but I am unsure of the years, and I dont know if it which would fir the SLP unit. Try searching for 'SLP takeoff', it might bring up some useful info.

EDIT: Remember that you don't have to do the swap right away. The car will still work fine with your stock rear end in it, no matter what engine is in the car. You will just get better traction with a limited slip differential.

 

i assume u still have the stock 10 bolt 2.73 rear end?

if so you would be better off to do some more upgrades other than a posi.

i would look into finding a 89+ thirdgen rear end if ur lucky a 9 bolt with a good gear ratio and posi would be a nice find.

https://www.thirdgen.org/newdesign/tech/techdb.shtml

if u want to keep ur rear and and you want a cheap route.

look into the slp posi for 100 bucks, an install kit, a set of used 10 bolt gear and 28 spline axles which came on the 89+ rear ends.


also did u try some searching on the site?

https://www.thirdgen.org/techbb2/search.php


Ward u got me by a minute

 

Yea, but it took like 5 minutes to type all that up