I swear i had seen a thread on this before, but i cant seem to find it now. I'm looking at carriers for for 10 bolt currently open diff '88 IROC but am curious as to what one to get. I've tried looking it up and talking to a couple people about it but am confused as to what is posi and what is limited slip. First i was told limited slip is open diff, then i tried looking it up on the internet to be told Positraction is GM's trademark name for limited slip, then i'm told limited slip is not quite posi but allows one wheel to spin so much before the other begins to spin with it. So my question is what is posi? What is limited slip? and which would be a better carrier?

LS http://www.summitracing.com/parts/au...t/model/camaro

P http://www.summitracing.com/parts/yg...t/model/camaro

Or is there another one out there that's better than these 2?

 

The "trademark" thing is correct. Posi = limited slip. Open = unlimited slip.

Not the Auburn, it is inferior. The Yukon is OK. The Eaton (NOT Gov-Lock) is probably "the best" of the clutch-type units. Other choices would include the gear-type ones; the Zexel Torsen such as were used in 98-02 4th gens, or the TrueTrac.

 

I got an Eaton true-trac. I read that the clutch one gives power to the wheel with less traction, and the true Trac give more power to the wheel with traction. plus, it's cheaper and no clutch is to wear out.

 

A limited slip differential (LSD) is a differential that applies power to both wheels through clutches, cones, special cut gears or other device. Eaton makes a clutch type LSD that was used in the Chevy muscle cars from the mid '60s to the early '70. Chevy called this Positraction, which was shortened to Posi. Eaton has a trade mark on both of these names. So the answer to your question is Posi is the brand name for Eaton's clutch type limited slip differential. Asprin was Bayer's trade mark name for the pain killer that they invented, and Rollerblade was the trade mark name for the first inline skates. These names became so popular that people began calling all pain killers "Asprin" and all inline skates "Rollerblades". The same thing happened to the Eaton Posi. People began calling all LSDs "Posi". People who don't know any better began calling standard differentials "limited slip", which is completely wrong. I've also heard people call a true LSD a "full posi", which makes no since at all.

To answer your other question, I like the Eaton Posi for most street/strip use. Yukon also makes a good differential called the Dura Grip. This is a copy of the Eaton Posi. Be ware of people who call the Eaton Governor Lock a Posi, because it's not the same thing. You don't want the Gov Lock. The Torsen and Eaton Truetrac are also good. I don't like the Auburn at all. The best differential for you will depend on how you want to use it.

 

This is what my Eaton Posi. install looks like and would be very close to what you can expect when upgrading to this type of new L.S.D.
The clutch type posi unit like the Eaton is pre loaded with 400lbs pressure and the clamping force to the plate’s increases with toque applied. The more torque the greater the pressure. You do not have to wait for a wheel to spin or slip.
You should be able to pick up a new Eaton Posi. Unit at a good price (lower than what I paid) at Toms Differentials on line.
Heres the unit at Eatons site = http://www.eaton.com/Eaton/ProductsS...als/PCT_221429

My build = https://www.thirdgen.org/forums/tran...de-photos.html

 

ok, i have a question, i have a lsd with 2.73 gear (and no rear brakes) so why is it that only one wheel will spin, unless i hold the brakes ... bad clutch or something like that?

 

Either you don't have limited-slip but just think you do, or it's totally wore out like yerbasic typical Auburn (which is why we recommend against buying an Auburn).

 

Barlow8869, if it's the factory installed LSD then it's an Auburn. When the Auburn wears out it will act just like a standard differential, allowing only one wheel to spin. The only way to fix it is to replace it. You can't rebuild the Auburn. When it wears out it is scrap metal.

If you have the Governor Lock (installed in a few 3rd gens) then it probably has a tooth broke off of the governor. When this happens they will no longer lock up and will act like a standard differential. The governor can be replaced, but the last one that I bought was $75 and that was more than 10 years ago. You also need a special tool to remove the governor, which is around $145.

The biggest problem in your case is the 2.73 gear. I don't know of any after market 2 series LSDs that are worth having. The Auburn and Gov Lock are all that I know of with 26 splines.

 

if that was the case, it would never spin more than the 1 wheel, correct?

 

that is just my luck, i want to keep it stock (and yes, i know it is just a low end iroc) for my son's first car ... it should be one of the cooler cars on the road by then, maybe even worth something, who knows ... lol

 

If you installed a new Auburn and the car was driven like a normal car then it would last for many years. If you do water burnouts or brake stands you will kill it pretty quick. Sadly, the Auburn is about the only option for a 2 series.