I have a 9 bolt rear end, does that mean its automatically a posi unit? From what I see its only a one tire fire setup cause only one wheel launches it and burns out and thats the driver side back wheel.

If the posi is broken, can someone provide me with a link to where I can get one because I'm completely stumped as to where they would be located. thanksss

 

No.

Check here for some info that may be helpful:

https://www.thirdgen.org/forums/afte...er-9-bolt.html

JamesC

 

thanks for the quick response i appreciate it

9bolt.com here i come

 

Yours is probably worn out. You can repair the Borg Warner posi. You can send it to Pontiac Posi Rebuilders or do it yourself. There was a thread on here somewhere that explained how to do it.

 

nope sry... u cant rebuild the stock 9bolt posi. its a cone style posi. u have to chuck the whole housing and replace it with a new one. sry guy. they are mucho $$ to i think like 450-500$ and ur stuck with a new stock posi... a couple water burnouts and kiss that bad boy gbye lol

i have a 9bolt on my 87 formula 350 and my 86 TA with a 305TPI... both do the dreaded one wheel peel.... both have posi both are worn. both have 130,000 on them. my 87 formula 350 i took to the track before i tore the motor out and i have rubber all over the passenger wheel well only and quarter panel lol... thats whats responsible for my 2.2-2.8 60's

 

To repair the BW posi you put the cones in a lathe and cut the small end to reduce the thickness of the cone and allow the cone to make contact with the tapered hole in the case again. Then you put a shim between the axle gear and the cone to restore the gear mesh between the axle gears and pinion gears. It isn't that hard to do. The Auburn can not be repaired like this because the cone is part of the axle gear.

 

Nope sry you can rebuild the 9 bolt. As biggearhead said get the cones turned down on a lath and then shim it tight. As long as the carrier is not chewed up they are rebuildable.

 

I couldn't find any info about telling a LS one from a regular one. Mine's a 9 bolt, 3.08. 85 trans am. A tag on the cover says "P/N 14094384 Ratio 3.08", and the big gear says "0575/029012 BW CK 3.08 D"
http://i278.photobucket.com/albums/k...ransam-067.jpg
http://i278.photobucket.com/albums/k...ransam-070.jpg
If I raise both wheels and turn one wheel, the other doesn't turn at all. If I raise only one, the raised one can be easily turned. I don't know if that means it's open, or just a very worn out LS.

Based on the pictures in my official manual, I think it's just open because there's two discs bolted together against the big gear and not just one. That's the only visial difference I notice from the exploded diagrams. Is that right?

I haven't driven the car yet (bad motor, swap just about done), I basically just wanted to be safe and change the rear fluid, now I don't know if I need the additive.

 

The 9 bolt uses a Borg Warner LSD. It has some small square windows in the sides of the case. You can look into the case and see the springs in the center. If there are no springs then it is probably a standard differential. I haven't seen a standard differential in the 9 bolt, but there could be some.

This is a 9 bolt B-W LSD.

 

The hole's too small to see if there could be springs. I can barely see gears turning inside and that's it. Based on the outside appearance though, I think mine's just an open. My biggest clue based on the diagrams in my book is the one vs two discs bolted to the gear. Plus that sharper ridge to the right of the gear.

Open? In a Trans Am? Lame.

Does that look right?

And another REALLY STUPID question: that rubber plug halfway up my cover plate, that's where I refill it, right? I was expecting the hole to be on the top or side of the housing, and the book says tighten the plug to 25ftlbs. I always figured the gears were completely submerged in the oil, not just the lower half.

 

You cant really go by outside appearance. I have heard that there are open 9 bolts but i have never seen one myself. The best way to see if yours is a posi or not is to lift the rear up and spin one wheel. If they both go the same direction you got posi. If it has a tag on it saying posi lube only it is as well. Also, you will not be able to see anything in the posi from the outside. Those two windows are there just to see if the cons are touching the case. So you can only get a view of a portion of the con and thats it.

In regards to the rubber plug yes that is where you fill it from. You can either use suction to pull the diff fluid out (ive done it a few times), or just pop the cover off, replace the cover gasket and refill through that hole.

 

I spin one wheel and the other does nothing. So I don't know if that means open or worn out.

 

Most likely worn out. Dont do any burnouts with it in that condition. It will wear it out even worse and maybe even break some teeth off the gears. If its doing one wheel peels it time for a reshim/rebuild.