What rear do I have in my car? The thing is bone stock. I am looking for what stock gear ratio I have, and if I have positraction? I am ready to swap that sucker out.

 

only way to know is pull the rear cover, count the teeth on the ring gear and pinion gear, divide the pinion gear count by the ring gear count, youll know for sure. put the car up on jackstands in the rear turn the rear wheels if they both turn the same way its probably posi. post up a pic for us to look at and someone will tell you if its posi.later jimmy

 

Bone stock without changes, the most common would be a open rear with a 2:73.

 

Is there a better gearing ratio I can or should go with? I have an ausi rear available with what I think is the same gear ratio, but it has positraction. Guys asking $250. I am 99% sure mine does not have positraction because when I peeled out, there was only one skid. I will lift it up and turn the wheels. If it doesn't have posi the tires would spin opposite directions correct?

 

Be aware that a used 9 bolt is very likely to have worn cones and have no/weak posi as well.

 

Why not look at your RPO sticker? It's as easy as opening the console lid and looking at the sticker. Chances are you'll see GU2 listed on there, which indicates 2.73 gears. If you happen to spot G80 next to it, then you did get posi originally. GU4=3.08, GU5=3.23, GU6=3.42. Most LG4 powered cars with a 700r4 did get 2.73's though.

 

you are correct! GU2... 2.73 gears. No posi.

 

Here's a more detailed question about the rear I am looking at: it is from a car with about 80k miles. I have not looked inside it but how would I tell if the cones and posi are worn out by just looking at it? We can put a torque gauge on it. We can try seeing how much it takes to turn an axel before it slips. Guy thinks it should be over 45 ft lbs???

 

Only way to know is to actually test the posi unit - go out on the street, light up the hydes, and see what it does. If it only leaves one track, then its worn out. If it leaves two, then its probably ok.

 

can the posi be rebuilt? I've seen them before, I know its a system of springs and such. Guy says also its a 2.77 gearing, is that acurate? How long does the typical posi last?

 

2.77 is a correct ratio for the 9 bolt. As far as rebuilding them, yeah you can, sorta. In other words, you can't get any new parts for them, but there's a tech article on here that tells you how to mill and shim the cone clutches in a 9 bolt posi to where they grab good again. The cones can't be bottomed all the way out in the carrier, or it's too far gone to be shimmed. Since the one you're looking at supposedly still works, it should be shimmable. "Shimmable", I wonder if that's even a real word. Lol. Like Air Adam said, probably the best thing to do is put it in the car and try it out. If it won't fry both tires reasonably well, then look into shimming the cones to make the posi tight again. I also agree that it should take at least 45 ft. lbs. or more to get it to slip. Anything less than that would indicate some pretty weak clutches in the unit.

 

Easiest way to check axle ratio is to put the car in 3rd gear in an automatic (1:1 ratio) and drive at 70 mph. Your RPM will tell you the axle ratio.

2.77 = 2770 RPM
3.27 = 3270 RPM

 

In theory that might work, but in practice it probably won't - the guages in these cars are notoriously inaccurate. I've seen tachs that were off by more than 10%, same with speedometers. Tire diameter would also be a factor as well.

 

cone posi's cant be rebuilt since the way they work is metal to metal contact it wears itself to **** when its worn out. sure u can mill and shim it to work again. but after you do that youd probably wanna sell the car or sell the rear seeing as how its not a real and just a band aid fix. its better to just trash it when it breaks and get yourself a posi with clutches seeing as how clutches are rebuildable