ok last spring i bought a 85 T/A parts car with a BW 9-bolt disc brake rear w/ 3.08's and i hae had the cover off to confirm this. the only thing is i dunno what a posi unit for one looks like i know what they look like in the 10 bolt but i dunno if its similar or not. i thought that ui had read somewhere one time that in 85 for some odd reason that rear also came w/ 3.08 non posi disc and 3.08 posi disc and so on. is this true? does anyone have a picture of te insides of both to help me out cause if its non posi its gone since i dont need anymore junk laying around.

 

The 9 bolt posi is a cone type posi that's next to impossible to see because the carrier closes completely. Your best bet is to test for it. See if you can get one axel spinning without the other one moving. If you lock one axel in place it should take 30 ft lbs or so on the other one to get it to spin.

 

well im still kinda new at rearends and im not sure of what you mean by sone. i know when i had the cover off to change fluid it was sorta funnel shaped and ring gear on driver side. im lost

 

My point is that you can't see inside the carrier unless you take it apart so there’s no way of visually checking to see if it has posi. The only way to test it is by physically locking one wheel (or axle if you don’t have wheels installed) and trying to turn the other. It should take at least 30 ft lbs to force the wheel to move.

 

If it were a 10 bolt you could tell by looking at it,you would see the springs,clutches.al;so if it were a govloc you would be able to see it.

 

ok that will help me alot see i didnt know if it had one style like it does or 2. ill test it and let you know. when i test it though do i use tq wrnch and where would i attach it to to turn?

 

Well, to start off my reply. You probably have either the 2.77 or the 3.27 ratio. The 3.08 ratio only came in the ten bolt rears. The news you're really not going to like is the fact that almost all of the nine bolt posi units I've ever seen are almost always burned out, and no longer working. The posi ones are funnel shaped like you described, and are closed to where you can't see inside the carrier itself. If I remember right, you can see the spider gears on the open carriers. You might get lucky and actually still have a working posi in it, but don't get your hopes too high. As far as figuring out the ratio, I had a 3.27 nine bolt, and it had 3.27 stamped right into the side of the ring gear, unlike ten bolts where it's usually the teeth numbers divided by a colon (ex. 11:41), so you have to do some dividing to figure it out.

 

it is infact 3.08 i have had the cover off and it is stamped on the ring gear 3.08 and i even counted it and came up with 3.08. i also dont quite understand how im to go about testing the posi if the rear isnt in the car and do i use a tq wrench if so where do i put it on to turn it? im thinkin that it might be a diff rear in the car cause you can tell the car was hit pretty hard on he driversideat one time the whole rear quarter is bondo i hit it w/ lug wrench as hard as i could and just left lil imprint! its all cracked up too inside across the hump in the back the metal has ripples in it. the rear is in good shape though

 

Wow, that's pretty weird that it has 3.08's. As far as I know, they were never offered in the nine bolts, but anything's possible I guess. As far as checking the posi, I'd just grab a 3/8 or 1/2" drive torque wrench and use one of the lug nuts to turn one of the axles while you have a buddy hold the other axle still. If the torque wrench reads at least 25 ft. lbs. or better before your axle starts to slip and turn, then your posi is probably still good. The simple old torque wrenches with the beam/arrow style pointer should work just fine to do this. You could use a click style, but you'd have to keep readjusting the setting to figure out what the actual resistance is.

 

there is a picture of my carrier with 3.27 gears in this thread if that helps.

 

yes, they had 3.08 and 3.70 stock back then in the 7.75 rear. posi and open. although I have never seen a 9bolt open disk rear only the open drum 9bolt it is possiable

 

I think you've got a valid point there. I don't remember ever seeing a disc brake version without posi either. Well, if you want to be technical, about 90% of the disc rears might as well be open, since the posi burns out so often, but they start out with posi originally!

 

i still gotta check it i need one of my friends to show and gota get a tq wrench then mabey wee can test it