I recently parted out a 91 formula which had the WS6 suspension. I decided to keep the rear end for myself. It's a posi unit. I was talking to someone and they said its a rare rear end and worth a good amount of money. He said its form Australia. It had drum brakes on it. I'm sand blasting it up and cleaning to look good. Is it worth money or is he full of it. thanks

 

Sounds like a common 9-bolt rear. And with the drum brakes it is worth about $150/200 max.

 

Yah, sounds like the basic Aussi 9bolt...

I do have the Aussi Calipers/backing plates if you wanna do a Rear disc convertion

 

That's Firebird owner talk. If he thinks it's so "valuable", get him to tell you what he thinks it's worth, and settle on some suitable fraction of it, and sell it to him, and let it be garbage infesting HIS garage. If I were you, I wouldn't be wasting a bunch of perfectly good time sand-blasting it and all that; let the "greater fool" have all that fun.

Meanwhile, back to reality: nobody in his right mind wants rears with drums. "Rare" or not.

The 9-bolt's last year was 1989, except that a few left-overs leaked into early 90 production.

Therefore, if your 91 car had one in it, it didn't come there; and it can't be identified as a "91" rear. It's a 85-89 rear, that someone stuck in a 91.

Very very few 9-bolts came with drums. People avoid them like the plague.

I'd be much more inclined to suspect that it's REALLY a 10-bolt, and your friend is full of hot air. They're pretty easy to tell apart, after all; just count the bolts. Go do that, get some reality going on, and then make an intelligent informed decision based on facts instead of on ... organic fertilizer.

Might be a good idea to pop the cover off and see what gears are in it. If they're 3.08 or lower, then it's REALLY useless. If they're 3.23 or higher, and it's REALLY a posi (not just a "2 stripes" posi or whatever other so-called "test") then the carrier is worth a little money; not enough to retire on or anything, but enough to be worth not throwing away, just barely, if it's not too much trouble to hang onto it. The axles, if they're 28 splines, are also somewhat sought-after, if they're not too ate up where the bearings ride on them.

Personally, a drum rear, or a rear with the 82-88 discs, whether a 9-bolt or a 10-bolt, is less valuable than ZERO to me. I wouldn't accept one for free, if you tried to give it to me. Don't want it, period. I've paid people (1-800-GOT-JUNK type guys) to come haul crap like that off my property.

The rears that people REALLY want to find are the 89-up ones with the PBR aluminum-caliper disc brakes, 3.23 ratio or higher, and posi. If you had that, it WOULD be worth a little something. But it sounds like what you've got isn't near that.

 

9-bolts were the strongest rear ends ever installed from the Factory into a ThirdGen F-Body. That's probably why the previous owner of the 91 installed it in the first place. Any thirdgen 9-Bolt POSI rear end is stronger than an equivelant thirdgen 10-bolt POSI rear end.

It's not very common to find one with Drum brakes installed on it. I'm pretty sure they used the drum brake set-up in the earlier 9-bolt years,........ Like the 85-86 F-Birds. ALL 9-bolt rears used 28 spline axles and the axles are NOT the same as 10 bolt axles. ( no "C" Clip, they bolt to the flange ) Not all 9-Bolts are POSI.

Most of the drum brake 9-bolts I've seen have 3.08 gears, but tI've been told that some were equiped with 3.70's from the factory too. The "lower" number the ratio the better gas mileage you will get; the "higher" the ratio the quicker the car will be off the line.

Turn the pinion flange and count the rotations or open the cover to find out what the gear ratio is. The "higher" the number the more $$ this rear will be worth.

 

Geez, Sofa... Talk about not holding back.



FWIW, I found an '89 Posi nine bolt @ 3.27 with PBR's for 300 bucks. Took me 2.5 years to find that deal.

 

Isnt the aussie rear end a Borg Warner Rear end? I have one on my car from an 87 Formula with 3.45's in it with disc brakes. Its something i havent really looked into but now im wondering, i haven been under the rear part of the car to see if its true or not and im just going off what the previous owner said, That it was an uncommon rear end made by Borg Warner? As for anything with drum brakes i would not pay anything for a rear with drums on it, it might turn out to be rare but that does not automatically mean its worth a ton of money.

 

Well I looked into a little more tonight. It turns out its a 10 bolt and its deff a posi. Not sure on the gear ratio in it. I know the car it came from was a 305 tpi and a 7r4.Thanks

 

That'll be a 2.73 (or would have come that way, at least....)

VERY VERY VERY VERY VERY poor odds that it's a posi. If it's a "2 stripes" posi, and you haven't physically looked at the carrier ( which I'm guessing you haven't since you don't know what the gears are), then it's probably not a posi.

But it hardly matters... nobody wants a 2 series carrier and drum brakes, anyway. It's worth approximately its weight in steel; which is what, 3¢ / lb? AFTER you buy the gas and spend the time and wear and tear on your truck to haul it to the junkyard. In other words, it has NEGATIVE value.

 

Sad but true.

 

I don't know much about rear ends. How do i tell whether its a posi or not when i take the cover off. Thanks

 

Take a pic and post it.

Basically, if you look inside the little "window" of the carrier, you will see some parts; including a shaft about ¾" in diameter held in by a small screw, and 4 small gears. If there's anything else in there, especially springs, then it is, or was at one time, a posi. If you see 2 little weights on 2 little pins, then it's an Eaton Gov-Lock aka Grenade-Lock.

 

Posi's have a spring assembly in the middle of the unit that engages both axles. Looks kinda like this:



This one happens to be an Auburn 3.73. The UNLIMITED slip ones (AKA Peg leg) don't have those springs colored red and yellow in the pic.

 

Mine is 2:73s. It looks just liek that but i don't think it had that middle spring. it has both outer ones. Its also a 10 bolt. Is it worth hanging on too?

 

Depends on what you call "worth"...

Not "worth" anything to me. I threw a 2 series stock Auburn, which is exactly like the one in the pic except with only the yellow springs (sounds like what you've got), in the trash not too long ago. Not "worth" the shelf space to keep it, not "worth" the gas to haul it to the scrap yard to melt down. I'll sure never use it for anything.

Your concept of "worth" might be different from mine though.

If "worth", in monetary terms, means anything to you, look through the classifieds on this site. See what units like that are ACTUALLY selling for: not just what people are asking, but what they're actually GETTING. If anything.

Otherwise, "worth" comes down to, you can either use it or you can't. Only you can decide that.

 

What is that middle spring for? I will probably end up holding onto it or selling it. Thanks again

 

The middle one adds some more pressure to the clutches. Tightens it up a bit.

The stock Auburns only had the yellow ones, except that some of the later ones had one or 2 orange ones too. The aftermarket "performance" ones had the extra orange springs. AFAIK they all had the same clutch packs.

 

I have that 10 bolt 2:73 rear and it is drums, but after I had it changed to a 3:42, it spins both ways, so it was a posi, just not enough power before to spin the tires. Oh, it is a weak 305 auto. Andrew