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how can I tell if my rearend is posi in my 84 z28

10K views 17 replies 9 participants last post by  prostreet6t9  
#1 ·
How can I tell from the numbers on my rearend if its a posi? I believe It says GM N 22522676D A04 K2
 
#3 ·
#4 ·
SSedan64 said:
Even an Open Carrier can also lay 2 stripes so that's actually not a good method.
Jack up the Rear, rotate one wheel in either direction, if the other wheel rotates the opposite direction it's a Posi. Even this method can be skewed if the Posi is worn out.

I thought a ''posi'' rearend : the tires on each side of the differential would rotate the same direction if the posi is operational?
 
#5 ·
Crosley said:
I thought a ''posi'' rearend : the tires on each side of the differential would rotate the same direction if the posi is operational?
Thanks Crosley, :thumbup:
:embarrass You are correct, my description above would be correct for an Open Carrier :spank:
Posi Carrier will rotate both wheels in the same direction.
Open Carrier will rotate wheels in opposite directions.
 
#6 ·
Im with Crosley on this one, I have a posi in my camaro and it came out of 92 Z28 and both wheels turn the same direction on both sides when jacked up and spun. I have a 82 camaro standaed rear end and when one side turns the other side spins in the oppisite direction of the other when jacked up and turned by hand.
 
#7 ·
:thumbup: Well ive definetly got two black stripes, I always love a good experiment especially with fuel and 400 plus HP however that dont help me figure out what gearing this monster has.
 
#8 ·
Rear gear ratio??

If Posi, raise rear & turn wheel 1 Rev, count turns of Driveshaft.
If Open, raise 1 wheel & turn 2 Revs, count turns of Driveshaft.
3 & 3/4 turns = 3.73
3 & 1/2 turns = 3.42/3.55 etc..................
 
#9 ·
Ok I hope this dont sound stupid ......... raised the car all four in the air now when i spin the driver side the passinger side rotates the opposite direction but when i spin the passenger side the driver side does nothing. counting rotations of the driveline would you believe if i said it looks like the driveline and the wheel are about one for one? Check it out i take off in third gear so my wheels dont spin this thing dont know the meaning casual
 
#12 ·
Celtz said:
Ok I hope this dont sound stupid ......... raised the car all four in the air now when i spin the driver side the passinger side rotates the opposite direction but when i spin the passenger side the driver side does nothing. counting rotations of the driveline would you believe if i said it looks like the driveline and the wheel are about one for one? Check it out i take off in third gear so my wheels dont spin this thing dont know the meaning casual
You do NOT have a posi. You got "two black stripes" because you were in a prefect straight line and both tires had equal traction. Go into a safe empty parking lot and turn the wheels all the way to one side and try to spin a donut, you will get ONE black stripe, I guaranty it. :(

Brian
 
#15 ·
91camaro91 said:
theres gotta be sight saying wether or not this car came with a posi. not sure if my 91 rs is or not..i doubt it because its the crap box 3.1 v6 option. but ya never know.
Yes, there is a tag or the number or something that will tell you. But jacking it up and spinning one wheel as you did with the other turning the opposite way or if you lift one side only and you can spin that wheel, it is NOT a posi, end of discussion there is nothing conflicting here, it is NOT posi. You got your two black marks because your were going in a straight line and offered the exact same resistance to both wheels. If you go out and look at those two black lines you will see that one fades away before the other, it is because one tire started loosing traction before the other an left the one to pull the car.

There is no more discussion about it whether it is or isn't, you have proven that it isn't. Discussion on what posi is or what every sure, we can still talk. But it is NOT a posi.

Brian
 
#16 ·
To figure out what ratio you have, put one wheel on the ground, spin the other one TWO revolutions, and count the revolutions of the driveline. Since there is a 2 to 1 reduction in the spider gears, the number of revs that the driveshaft spins to 2 revolutions of the tire, will be your gear ratio.