its for a 3.23 rear end but is that an open or posi? its a LG4 84 z28 with a t5

if you jakc the rear of the car up ans spin one wheel by hand and the other turns in th esame direction then you have a posi/limited slip rearend. if the other wheel spins in the opposite direction then it is open.

GU5 only states the gear ratio, look on the code list for G80. if it's there, you have posi, if not, sorry

well my console sticker does not have G80 so i dont have posi. how would i go about making my rear end posi?

Change out the carrier.

Guys, my RS has a rear end from an '86 IROC. It had G80 GU5, but when I spin it in the air, it spins opposite directions. If you burn the tires from a stop, it leaves two black marks. The posi works good, but the tires spin opposite in the air??? whats the deal

the deal is you have an open differential rear end. you might get both wheels to leave a black mark whe nyou floor the gas but if you say the wheels spin in opposite directions when raised up then it is not a posi.

then how do both wheels spin?

My 93 S10 is a posi truck(i know this for a fact) and its wheels spin opposite directions when spun in the air too. So don't discount it just yet. Unless theres a big difference between limited slip and Posi...

Posi is a type of limited slip. It's the shortened name for Chevrolet's Positraction axle and has seemingly become a generalized term for any limited slip axle.

Bottom line = there is no difference between posi and LSD because posi is an LSD. There are different types of LSDs (clutch, viscous, etc) though.

That's not really a "posi", although it was marketed that way.

It's the Eaton Gov-Lock, aka Grenade-Lock. It has NO POSI ACTION WHATSOEVER until the difference in wheel RPMS reaches 150 RPM or thereabouts. That way, it acts like an open during normal driving, going around corners and such; but if a wheel spins, it locks up with a bang, explodes, and sends shrapnel through the axle cover and into the gas tank.

"Positraction" was GM's trade name for limited slip back in the 60s for a short time. Great name. So great, it stuck, even after GM quit using it. Other mfrs have trade names too; Traction-Lock, QuadraTrack, SureGrip, and so on, are all the same thing. I think GM has brought the "positraction" name back recently, since it's such a great marketing tool.

The "real" posi we have become familiar with has clutches that clutch the axles to the carrier, such that a certain minimum amount of torque (usually 50-80 ft-lbs or so) is required to force the axle to turn at any RPM different from the carrier. But there are other types; such as the Torsen used in the LS1 cars, which uses a worm gear system. That one provides very good "posi" behavior, but will allow the wheels to turn opposite ways with very little torque.

You're right, I've recently had a chance to see the difference between posi and Limited slip. A good way to test to see if you have limited slip is to raise your rear tires and jerk one real hard, it should make the locking weights fly out and lock up the other wheel. At that point it acts like a locker, otherwise it will act like an open differential. It really is kind of a cool mechanism. Actually if given a choice I prefer it over true posi.

You're wrong; there is no difference between "posi" and "limited slip".

As explained patiently and thoroughly above, "Positraction" was GM's tradename for "limited slip". Therefore, there is no difference between the 2 terms. They are different spellings for the name of the same part.

The action you are describing is that of the Gov-Lock. It is not typical of limited slip designs. It is not particularly "cool", it is stupid for a performance car; while at the same time, it makes alot of sense for what it was originally designed for, which was light military all-terrain vehicles intended specifically for off-road use. In addition to its inherent weakness, it promotes instability (tendency to cause loss of vehicle control and wrecks), by way of the sudden application of drive power to different wheels, in the middle of a spin. As also explained patiently and thoroughly above, it is not suitable for a high-powered vehicle, with traction, on pavement.

Some people are so slow or Dumb that they still think (if they think) that the slang term Posi (Short for Positraction) is different then a LIMITED SLIP. No matter what we say they just don't get it, that it is a LIMITED SLIP.

Ok i get what you guys are saying... yes posi is a limited slip. I get that. I was talking about styles of posi and i just refer to the clutch pack style as "posi" and the Gov. Lock as "Limited Slip". So in that context you have to agree they are different.

Anyways back to the original topic. The Gov. lock system acts like an open differential most of the time even thought it is a limited slip rear end. which could be why his wheels act like they do when he turns them in the air.

No, I don't.

Language is a very cool thing. I don't know how familiar you are with it, but I'll give you a couple of quick pointers.

Language is a method of "communication". "Communication" is the process by which transmitters of information (speakers, writers, artists, actors, etc.) pass information to receivers (listeners, readers, viewers, etc.) Language is composed of these objects called "words". "Words" are symbols. As such, they have various properties, one of which is called "meaning". Each "word" stands for something: that is, there is a "meaning" generally agreed upon by the users of the language as a group, as to what each "word" stands for. In order for "communication" with "language" to be effective, everyone who uses the "language" must universally agree on what "meaning" those symbols called "words" carry. Without agreement, communication breaks down.

Language isn't something that some ONE user can just arbitrarily declare that all of a sudden, this one "word" now has a different "meaning" when he uses it, than it does when everbody else uses it. Language ceases to work when that happens. The ONE user who thinks the "word" should take on his personal "meaning" rather than the generally accepted one, and then gets mad at everyone else because they prefer to stick with their familiar, comfortable, long-agreed-on "meaning", fails to communicate properly as a transmitter of information, because he has corrupted his message as far as the receivers are concerned. This often leads to the ONE person suffering ridicule and other forms of shame. Don't let it happen to you.

So NO, I do not "have to" agree that the "definition" of these 2 "words" should be changed to your new one.

"Posi" and "limited slip" remain the same thing. For all the rest of us, anyway. In ANY "context".

Likewise, the "original topic" of an Internet message board post can usually be found in the title and the first post. That's another of those "word" things, you know, those things with "meaning". The "meaning" of "original" is closely related to "beginning". In that post, the "original topic" was whether RPO GU5 contained any information as to whether the rear was posi or not; and had NOTHING to do with the Gov-Lock. That came up later, when the usual so-called "tests", NONE OF WHICH provide conclusive results, were brought up.

As always, the ONLY way to determine if your car's rear actually has posi or not, is to take off the cover and look. What you see is what it has.

i wasn't saying that you had to agree with my "new definition" i was just saying you had to agree that Gov lock and clutch posi are different. Otherwise you could just mix and match parts and it would work, which it doesn't.

Different designs of a LIMITED SLIP and NOT a Positraction (posi) which was just Chevolets marketing name for a LIMITED SLIP.

Yes, thats exactly my point. Thank you.

Gotta love these resurrected posts!

JamesC

D00d, give it a rest.

No, that was NOT your point. Quit trying to weasel out of getting caught in a mistake.

You screwed up, pure and simple. What you said is WRONG, and coming back in here and twisting it around this way and that with new "what I really meant" comments just makes you look even more juvenile and inexperienced.

The correct response when you screw up in public is something along the lines of "oops, I'm sorry, I see I screwed up; in the future I'll keep my mouth shut and I'll speak up only when I REALLY know the truth, and I won't just make stuff up to hear the sound of my own voice while I run off at the mouth".

Try it sometime. Learning to admit one's mistakes and own up to being wrong is a necessary life skill that we all have to develop sooner or later if we want to progress in life. It's part of growing up.

/rant mode off

"It's better to be thought a fool, than to open your mouth and remove all doubt".
— in various forms from Samuel L. Clemens, Abraham Lincoln, Confucius, Proverbs 17:28

Which is exactly what the above post was about but somebody had to totally misread it.... i DID apologize and admit to fault, and I thank you for correcting me but i wasn't completely talking out of my @ss like you seem to believe.

ok here we go. I have a GU5 code on my 86 iroc. I went to do a brake job on all four wheels. when i took of the right rear drum the brake shoes and all the springs were covered in gear oil. well thats what it smelled like anyway. friend of mine told me it could be a brake cylinder that is leaking. but it really smells like gear oil. i looked at the seal just befor the inspection plate or water gaurd whatever you call it. and i can see that the seal is kinda crinkled. So my real question is... how do i replace the seal? someone told me i need to remover the rear plate and there are clips in there if it is a posi rear end. if i remove the clips the axle should come out. Is this true? ive never done that kind of work on a rear end before. so im kinda gonna just wing it myself and fix the problem before i put new brakes on my Iroc. I thought that the rear end was a TRUE posi. since both wheels leave black marks evenly when punched from a dead stop. can anyone suggest a place that i can get the seals from on the net somewhere since autozone doesnt seem to have what i need online. i dont see an ID tag anywhere on the rear end. is there a special place that i can see the ID numbers so i can get the right seals i need? i thank you for your time. Mike

Sticky at the top of the page.

JamesC

If the seals are leaking, you'll probably need to replace the bearings as well. If the axle itself is grooved badly, off-set bearings will work, though I'm not convinced that the internal seals work as well as the OE type. Should the axle(s) be trash and you wish to use OE seals, your only choice really is to replace everything: axles, bearings, and seals.

Autozone:

Wheel bearing 5707
Wheel seal 8660S
Off-set bearing TRP1563TAV

Summit:

Moser C-clip relacement axles MSR-A102604
Wheel studs 12mm x 1-1/2 MSR-8254

JamesC