Were all 9 bolts posi, and did the 9 bolt come in the 91 RS wit a 3.1. if it was an option what do i look for to find out if i have one, is it as easy as looking at the rear end cover and counting the bolts or is there a code on the rearend

thx

 

Look at the cover and count the bolts. If you want to know if it's posi, or what ratio it is, the only sure way to know is to pull the cover off and look.

 

ALL 9 bolts were posi

 

First question...NO. And its called a Limited slip RPO G80 and was a extra cost option.
Second Question....Only 10-bolts were used on 91 RS cars. Also Gm stopped installing BW 9-bolt rears in 1989.

If you have a BW 9-bolt, it is not stock and was swapped in.
Last question..Just as easy as you posted.

 

I have a 9-bolt open rear.

Not all 9-bolts were posi.

 

Based on the information that I have, all 9 bolts that were placed in thirdgens were posi. I do suppose there could have been an "option" for a 9 bolt non-posi rear but a non-posi 9 bolt must be rare if they do exist.

 

My local Pick a part right now has 4 cars with 9 bolts, 2 posi and 2 open. All the open ones have been drum brake and 3.27 gears in 1985 cars. One other liitle known fact is the drum brake 1985 axle has a larger Dia. O.D. on the axle and a Disc brake rotor will not fit on it.

Jerry

 

Maybe that's why I was unaware of them. So I guess it's probably safe to say that ALL 9 bolt rears with DISC brakes were posi from the factory.

 

No....RPO G80 Limited Slip & J65 Rear Disc Brakes were extra cost options. Gm didn't give anything away. I know because I am the original owner of 1987 IROC-Z.

 

Looks like I'll need a rear end swap when I reach the need for rear discs.

Time for a 9".

EDIT: Mine is a opne 9-bolt with 3.08 gears and aluminum drums. Exactly as it came from the factory.

 

what kind of power can you put through a 9 bolt

 

"If you want to know if it's posi, or what ratio it is, the only sure way to know is to pull the cover off and look."

I have an 89 10 bolt rear end. I'm sure it's a POSI because when I burn rubber I leave tracks from both tires. I'm not sure what gears I have though.

 

IIRC, the factory officially states that this rear end can support up to about 300 HP before it starts breaking. I've heard stories of people abusing them with 500 HP big blocks, but this has yet to be verified.

Honestly, the 9-bolt seems like too costly a rear end because the parts are hard to find and anything you can find for them are bound to be used already. Plus, I know that if your 9-bolt came with anything numerically lower than 3.27 gears you have to get a 3-series carrier to fit numerically higher gears in. Not much aftermarket support for this rear, either.

 

T-5 equipped Iroc z28's from 86&87 had 3.45 gears.

 

The 91 Rs came from the factory with 3.42s on the manual and 3.23s on the auto.

G80 is the code you would look for on the RPO list usually under the console lid. Other ways are to look for a metal tag hanging off of the diff cover saying BS about using limited slip fluid. and another not so great way to tell is to jack up the back and spin a tire, if they both rotate the same way you may have a posi.

Only way to know 100% is to just pull the cover, the fluids probably long past due for a change anyways.

 

I will tell you what I know about my 82 with the Iron Duke. It is still stock, 9 bolt I believe, with posi and 3:23 gears. This car is pure stock with no options so why did I get this rear end, it also has the aluminum drums. I think I have all the info listed above right so feel free to correct me if I am wrong, when I peel out both rear tires spin.
lawrence

 

Wasnt it in 87 they started with the 9bolt rears?

 

You're right, sorry I just went outside in the cold and counted and it is infact a ten bolt. First time I ever looked at the rear end and the cover looks a little rusty. It is still a posi with aluminum drums and the 3:23 gears. My bad
Lawrence

 

Yes it could still be a posi, just the 10bolt version. 3.42s came from the factory with the manual trans. Im guessing its had a carrier swap somewhere in its life.

How exactly do you roast both tires with 70HP and 100lb torque? lol

 

ONLY IN THE DIRT
ROLMFAO
And it's 90 hp
The rear end is stock, believe me, I think it's the limited slip but it is still posi none the less.

 

90HP/135lb right out of the factory 23 years ago, im doubtful its still even at 70hp

 

I have a newer motor with 80xxx miles on it so yes it is still strong

 

Hmmm is strong the right word?

So why did you guys bring up a dead thread with a question not even related to the original post...

 

Just to make small talk.

 

That's one strong Iron Duke.

My stock LG4 in my TA would spin both tires on gravel and it was an open rear. But it wouldn't spin them on pavement till I installed the 3:73's with the darn Gov-Loc.

 

I have a rear end out of a 89 Iroc with disc brakes and posi (I think it may be in need for a overhaul). But I was wondering if my rear end is a 9 bolt or 10 and did GM put 10 bolts on camaro's in 89? I have read about 9 bolts and they are a lot of trouble to overhaul or install gears.

 

No more or less a hastle than a 10 bolt. Just a bunch more money.

EDIT: Sorry, more money to rebuild is what I meant.

 

The 9s ar emore rare so your going to be hard pressed to find parts in a junkyard compared to a 10 bolt setup.

 

If you don't abuse or do anything dumb you should never need a new rear or replacement parts for a 9 or 10-bolt. I only went from a 10 to a 9-bolt for the improved rear brakes on a 1989.

 

You mean like spinning the tires on ice and hitting a dry spot with one wheel when the speedo is pegged?

Or, bolting up a set of drag radials and a good short torque arm and pretending you are John Force? lol!!