Ok Im sorry for asking this but to be quite honest this is my first time pulling a differential cover off and looking at a rear end.

Im going to change the fluid but I had a few questions...
Do I have a posi? I cant tell. Also, how do I tell the gear ratio? Can someone highlight which gears to count or something? I was going to do the wheel rotation/driveshaft rotation thing but the shaft kept hitting my exhaust pipe and I also want to be more accurate.

 

the ratio should be stamped on the edge of the ring gear, something like 13/42. can't tell from your pic if you have posi. you need to rotate it and take a pic, or just look for clutch disk in it. do a search here and you'll find pics of posi carriers.

 

can you rotate the gears when there is no lubrication in it tho?

 

yes

 

There's plenty of lubrication on those gears right now to rotate it by hand.

I just happened to have the cover off of mine yesterday for a fluid change (well, I was doing that because I was replacing the pinion seal). Having had 2 other rears in the car in the last 5 years that were of the open variety and having had the covers off of them as well, I'm fairly certain that what you have is an open carrier. But, rotate it 90 degrees as suggested and post another pic.

BTW, you can tell if open or posi while you have it in the air by putting the tranny in park (in gear if manual), and with the park brake off, try to rotate one wheel by hand. If it turns and the opposite wheel turns in the opposite direction, it's open. If it doesn't turn, it's posi.

 

Rotate it around to where you can see in the "window" in the side of the carrier, and look for this. If you see it, it's posi. If all that's in there is 4 small gears and the pin, it's not.

 

ok, so I guess I have an open carrier.
Here is the pic I only see a few gears.

Oh yah, how do I find out the ratio? There is nothing stamped anywhere that signifies my gear ratio. I want to use the counting method

 

easiest way i can tell you is if you know that is the original rear/gearset, then u can simply look up the rpo codes and it should tell you.

otherwise, mark one of the teeth (marker or something) and count the teeth in the ring gear, then count the teeth in the pinion gear. divide and u have your ratio.

 

ok, this is what I got....
I counted 41 teeth on the big gear(ring gear???) and 11 teeth on the small gear(pinion?)

I divided and got 3:7272727272, so I believe its a 3:73 gear ratio.

Thats so messed up, why would I have rear disc brakes and a 3:73 gear ratio with no posi...I thought for sure I had a posi and ws6 :/

 

you can always hold your brake and slam your accelerator and see how many marks you leave on the round
... well u have manual sooo just do a simple burnout

 

Alot more people "think" they have posi, than really have it. This is a classic example of why taking off the cover and looking is the only way to know for sure. All of that crap about "2 stripes in a burnout" is especially not reliable. EVERYBODY thinks they have a posi based on that, since every once on a while at lesat, almost any car will do that.

My 83 HO car came with 3.73 (they all came with that), no posi, and drum brakes.

Your car almost certainly DIDN'T come with those gears, since they aren't OEM which we can tell because they don't have the ratio stamped on the edge; but rather thay have found their way in there sometime since. Which is a good thing. This is a classic case of why the "codes" are worthless and not to be relied on.

That's a 3-series carrier. So, that rear most likely came with 3.23 gears. That was a very common ratio in LG4 cars. On the other hand, the disc brakes are NOT common in those cars, and probably didn't come with that car. I'm guessing, just on a hunch, that the entire rear is out of another car, and has had the gears swapped in, and you probably still have the master cyl and proportioning valve form the drum brake system.

All in all, you did the right thing by looking and counting; even though some of it maybe wasn't what you wanted to see, at least you now know the truth, with absolute certainty.

 

welll you will know if u dont have a posi if only one wheel burns.... how is this false?

 

Because you may have a posi unit that only wants to work when it feels like it.

 

or some sorta lsd

 

The correct term is LIMITED SLIP. Posi is short for Chevolets trade name for Limited Slip (Positraction) on all 3rd gen cars. RPO G-80 Limited Slip Rear.

 

Thats pretty much unspoken knowledge :P and hardly has anything to do with the subject.

:lala: :lala: :lala:

 

[QUOTE]Originally posted by pasky
[B]Thats pretty much unspoken knowledge :P and hardly has anything to do with the subject.

Thats the problem when people use the term Posi and think its a super dupper rear diff that causes two wheel burnouts. When it is a Limited Slip and is just a traction improvement.
So if you want to use your unspoken knowledge so be it .

 

Yea its weird, I have an open rear end and have done 2 wheel burnouts and single wheel burnouts and I know that i don't have a limited slip. I took the cover off and checked it all out, just a 3.73 open drum rear end

 

posi = 2 wheel all the time... sooo?