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Posi diff, still good or not?

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Old May 29, 2008 | 11:45 AM
  #1  
mr.camaro's Avatar
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From: Canada/Qc/Montreal
Car: Red 86 Iroc-z / Black 90 Iroc-z
Engine: Mild 350 / Vortec L31
Transmission: TH700R4 / TH700R4
Axle/Gears: 3.42 / 2.73
Posi diff, still good or not?

Hi guys, i have a 86 camaro iroc-z, it has rear disc's and i think it has a posi diff, because i lifted the rear of the car and turned one of the wheels by hand and the other turned in the same direction. although in a straight line (hard acceleration/burnout) they always are equal and i have never had any one wheel wonders in a straight line. but if i turn hard and give gas one wheel will spin, harder to do if i turn to the left, but if i turn to the right it is very easy to spin only one wheel. is my diff really lsd? if it is can i get it rebuild? or is there a way to re'tighten something for example??.

Thanks guys.
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Old May 29, 2008 | 03:52 PM
  #2  
gcgarner's Avatar
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From: Morganton, NC
Car: '92 T/A WS6 Vert/1956 Chevy Nomad
Engine: 350 TPI
Transmission: 700r4 w/ Transgo Kit
Axle/Gears: 3.42 LSD
Re: Posi diff, still good or not?

RPO code G80 denotes Limited Slip ... but you can't always go by that on a 22-year-old car with multiple owners. You could always pull the cover and see.

I think someone told me that the posi units in our cars were Auburns ... and if they are, I've heard that they can't be rebuilt. Now, this is what I have HEARD. I don't know any of this for sure, so don't take my word for it. Maybe somebody can give more input?
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Old May 29, 2008 | 07:22 PM
  #3  
mr.camaro's Avatar
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From: Canada/Qc/Montreal
Car: Red 86 Iroc-z / Black 90 Iroc-z
Engine: Mild 350 / Vortec L31
Transmission: TH700R4 / TH700R4
Axle/Gears: 3.42 / 2.73
Re: Posi diff, still good or not?

but is there somthing you can do with the diff? like change the springs or somthing, and if i do take the cover off wont all the oil come out? and then il have to change the oil and the seal?
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Old May 29, 2008 | 08:42 PM
  #4  
gcgarner's Avatar
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From: Morganton, NC
Car: '92 T/A WS6 Vert/1956 Chevy Nomad
Engine: 350 TPI
Transmission: 700r4 w/ Transgo Kit
Axle/Gears: 3.42 LSD
Re: Posi diff, still good or not?

Probably needs a gear oil change anyway. Couldn't hurt. If you really want to know, take the cover off. And if it needs repair/replacement, you will have to take the cover off anyway.
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Old Nov 23, 2008 | 09:35 PM
  #5  
mr.camaro's Avatar
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From: Canada/Qc/Montreal
Car: Red 86 Iroc-z / Black 90 Iroc-z
Engine: Mild 350 / Vortec L31
Transmission: TH700R4 / TH700R4
Axle/Gears: 3.42 / 2.73
Re: Posi diff, still good or not?

Yes it is a posi, sorry if i havent replied in a long time, still need help for this problem!
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Old Nov 23, 2008 | 10:09 PM
  #6  
gurkgurkgurk's Avatar
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From: SF bay area
Car: 86 Camaro iroc-z28
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3.42 Posi
Re: Posi diff, still good or not?

Originally Posted by mr.camaro
Yes it is a posi, sorry if i havent replied in a long time, still need help for this problem!

our posi's are cone type posi's which means they cant be rebuilt like clutch pack style posi's, sure they can be ground down so theyll last alittle longer, but dont think of that as a fix. basically you just need a new diff
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Old Nov 24, 2008 | 01:51 PM
  #7  
Sonix's Avatar
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: Posi diff, still good or not?

Ok, you verified it as a posi then eh?
It should have the stock Auburn, which is indeed a clutch style posi. (the cone style is the one in the 9 bolts...). None the less, Auburn clutch style posi's could be rebuilt... if parts were available. They are not, hence, they are non-rebuildable.
If you buy an eaton, parts are available, and it is rebuildable.
No you can't shim it, tighten it, etc. It's wearing/worn out. Replace it with whatever you feel like.
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Old Nov 24, 2008 | 02:06 PM
  #8  
big gear head's Avatar
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Re: Posi diff, still good or not?

Auburn can not be rebuilt. They are also cone type. Eaton can be rebuilt.

There is a chance that the differential in your car is the Governor Lock. If it is then it will not lock up after you start moving. The governor is set up so that it can not lock up once you have reached a certain speed. This is a safety device to keep it from locking up at speed and causing you to loose controll. The Gov Lock is not a standard limited slip differential because it is not locked up all the time. It only locks up when one wheel spins faster than the other, as in when one wheel looses traction. If this is the differential that you have then that will explain why it will spin one wheel when turning. You have probably already exceeded the speed of the governor.

If you have an Auburn then it is possible that it is beginning to wear to the point where it doesn't lock up tight enough to keep both wheels spinning in a turn. I'd recommend running it as long as possible and then replace it wiht an Eaton.
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Old Nov 24, 2008 | 02:19 PM
  #9  
Sonix's Avatar
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: Posi diff, still good or not?

I'll be damed, I thought the Auburn was not a cone type... Oh well, mine exploded so I didn't autopsy it too much...
Mark/Junkyard dog/ Crossfire_83TA or whatever his name is here, had a thread showing how he rebuilt a 9 bolt cone style posi. He machined it with his drill press, and basically shimmed it tighter. Not for the faint of heart...

I was pretty sure gov-locks didn't come in our cars stock (although, as mentioned above, stock doesn't mean much knowing the age of these cars...).

Personally I replaced my auburn with a detroit tru-trac. They are cheaper then the traditional clutch style lockers, and have no clutches to wear out. A little different in design and how they work, but if it works....
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Old Nov 24, 2008 | 02:53 PM
  #10  
big gear head's Avatar
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Re: Posi diff, still good or not?

Some of the Camaros and Firebirds with the 7.5 had the Governor Lock. Most early to mid '80s 7.5 rear ends had the early style Auburn that split in the center. Sometime in the '80s they went to the current design Auburn. The '60s Pontiacs and Buicks with the 8.2 BOP 10 bolt rear end used a Borg Warner posi like the one in the 9 bolt. There is a shop in Ohio called Pontiac Posi Rebuilders that rebuilds these, so they probably do the 9 bolt unit too.
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Old Nov 25, 2008 | 06:36 AM
  #11  
mr.camaro's Avatar
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From: Canada/Qc/Montreal
Car: Red 86 Iroc-z / Black 90 Iroc-z
Engine: Mild 350 / Vortec L31
Transmission: TH700R4 / TH700R4
Axle/Gears: 3.42 / 2.73
Re: Posi diff, still good or not?

I opened it, it is NOT a gov/cone diff. its a 10bolt and has the 2 springs. my mecanique who changed the oil in it told me it was in great shape...but since the oil change is has bin about 25% better then before. so there is nothing i can do with this diff??. its very easy to make one wheel spin, like one wheel in grass just tap the throttle and there it goes...
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Old Nov 25, 2008 | 07:00 AM
  #12  
big gear head's Avatar
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Re: Posi diff, still good or not?

Should have either 4 springs or 5 springs. The Eaton has 4 (these were not installed in any of the 7.5 10 bolt rear ends) and the Auburn has 5. The Auburn was the only limited slip differential that was installed in these cars other than the Governor Lock, so that must be what you have. The Auburn is a cone type limited slip (posi), which means that it is not rebuildable.

Auburn

Gov Lock

Last edited by big gear head; Nov 25, 2008 at 07:06 AM.
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Old Nov 26, 2008 | 03:33 PM
  #13  
mr.camaro's Avatar
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Joined: Dec 2007
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From: Canada/Qc/Montreal
Car: Red 86 Iroc-z / Black 90 Iroc-z
Engine: Mild 350 / Vortec L31
Transmission: TH700R4 / TH700R4
Axle/Gears: 3.42 / 2.73
Re: Posi diff, still good or not?

myn is like the first pic!
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Old Nov 26, 2008 | 06:07 PM
  #14  
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Re: Posi diff, still good or not?

Can a mini spool be installed?
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Old Nov 26, 2008 | 06:35 PM
  #15  
big gear head's Avatar
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Re: Posi diff, still good or not?

Then you have the Auburn. There are 3 more springs on the other side that you can't see in this picture. It can not be rebuilt, so I recommend replacing it with a new Eaton when you get ready to fix it.

A mini spool or Power Trax locker can not be installed in the Auburn case. You must have a standard differential case to use them.
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Old Dec 1, 2008 | 12:51 PM
  #16  
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Re: Posi diff, still good or not?

Diggin up an old thread,
If you take the springs out of the diff, how do you get them back in.
I have the aubrun or 5 springs.
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Old Dec 1, 2008 | 04:50 PM
  #17  
big gear head's Avatar
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Re: Posi diff, still good or not?

First you put all of the springs and plates together the way that they will fit into the differential. This is much easier to do if the ring gear is removed. I use channel locks on both sides to compress the spring package and get the small end started between the gears. Then you just tap or shove them into position. A little grease on the axle gears will help them slide in a little easier. If you have the Auburn Pro then the springs are going to be much stiffer and harder to get it. I know that there are other methods of doing this, but this is what works best and quickest for me.
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