There is this posi rear end for sale for 100 dollars. I have only seen a picture of what it looks like from the outside. I have a camaro berlinetta when limited slip and i was thinking about buyin this rear end and installing it on mine. I havent checked it out in person yet, but do you guys have any suggestions on how to check if this rear end is still in good condition?

 

At the very least pop the diff cover to inspect the teeth and to verify that the rear is indeed a limited slip. A number should be stamped on both the ring and pinion to provide the gear ratio:

41 : 15 = 2.73
40 : 13 = 3.08
42 : 13 = 3.23
41 : 12 = 3.42
41 : 11 = 3.73

If the ratio is different than your current rear end, you may need to swap the drive or driven (or both) in the tranny to get an exact speedo reading.

JamesC

 

whats the difference between a limited slip and a posi rear end? If i decide to just buy a posi unit and install it, what would it take to do so?

 

Limited slip and posi are the same thing. Sorry, just reread your first post. Sounds like you're trying to buy what you already have.

JamesC

 

Odds are VERY VERY VERY low that you have limited slip aka "posi". Few enough of the performance cars were ordered with it back in those years; but almost NOBODY that was ordering the non-performance dress-up-only version of these cars (kind of a "chick car" in their day, you could say) were interested in that.

But regardless, before you buy ANYTHING to go in your car's axle, pop the cover off and look in there. Help prevent ugly surprises.

Likewise, before buying a rear end or any parts of it, LOOK AT THEM. That means, pop the cover off and look. DO NOT take the seller's word for what's in it!!! "Must be a 350, runs too good to be a 305", ".... out of a Vette" (yeah right, it rode around in the cargo compartment for a day, and now it's not in there any more, so it's ".. out of..."), "police interceptor", "almost as good as", "WS6", "HO", and so on.

If it's an Eaton Gov-Lock, you don't want it, because it isn't exactly a "posi" (among other reasons). So if this other rear is out of a truck, it isn't what you're looking for; unless you don't care how it actually works, and you just want bragging rights to tell people "yeah, I got a posi in it". For $100, that's probably what it is; basically worthless, and the current owner actually PAID MONEY for it and now is hoping to reel in the "greater fool".

 

my buddy has a 82 camaro, when he power brakes it....only 1 wheel spins.
On my 87 Trans Am when I power brake it, the drivers side tire turnes 1/4 then both tires will spin.
Maybe thats where hes getting confused.
A "true" posi if you turned a corner would wheel hop around the corner. A true posi, both tires turn at the same speed.

 

Ok..i dont think i gonna buy it. but whenever i peel out it does a "one wheel peel". So if i was to buy a eaton posi unit or something, would it be difficult to install? Its pretty embarasing to do one wheel peel outs!lol..especially in a camaro!

 

Your confusing a posi diff with a spool. Posi is short for "Positive Traction." It's just a name GM uses for their limited slip diffs.

 

a "true" posi....both tires spin the same ALL the time.

 

Spool
A spool limits differential rotation to exactly zero. A spool consists of a pinion & ring gear only, the centre is solid, the axle is one piece. A mini-spool is similar, replacing the usual diff centre with a solid piece, retaining the factory axles. Technically a spool is not a differential at all, but is used to achieve a similar effect to an LSD on some street & race cars.


Factory Names
In the 1950's and 1960's many manufacturers began to apply brand names to their LSD units. The most famous of these was Chevrolet's "Positraction". Since then, Positraction (often shortened to "positrac" or merely "posi") has become a genericized trademark for LSDs.

Other factory names for LSD's include

Pontiac: Safe-T-Track

Ford: Equa-Lock and Trac-Lok

American Motors Corporation: Twin-Grip

Mopar: Sure Grip

Ferrari: E-Diff

Fiat: Viscodrive