????

 

Nothing, they are one and the same.

 

Posi means that both of the drive wheels always spin at the same speed all the time. Limited slip allows one wheel to spin fast than the other for better turning, but if it detects one wheel spinning much fast than the other it makes them both lock up and spin. Both better than a differential where only the easiest wheel spins.

 

They are the same thing. There is no difference. They do the same thing, work the same way, and have the same effect. They are 2 different brand names for the identical same parts, down to the very part number in some instances. "PosiTraction" was simply GM's trademark for their limited slip rear ends in the 60s.

 

No, a "locker" or "spool" makes both wheels spin at the same speed all the time not a "posi".

 

Posi-Trac, Sure-Trac, Tru-Trac, Trac-lok, etc. they're all different names for a limited slip differential marketed by automanufacturers.

 

about the only true differance is the arrangement of the letters in the names, other than that they'er both the same.

 

So if everyone stopped calling there Limited Slip ( RPO G80) a Posi it would eliminate the confusing. But then we would have no questions such as "how can I tell if I have a Posi ???" :lala: :lala:

 

But calling it a "posi" is what it is.

It's short for Positive Traction by GM.

It's like calling a Trans Am a "TA", or Throttle Body Injection a "TBI".

It's just an abbreviation for the real name.

 

Yes, Positive-Traction is GM's name for a Limited Slip Rear. However; to the uniformed young owners they think its a very special rear for racing, burnouts & etc. So call it what it really is and end the confusion. Its like calling a Wheel a Rim....

 

I don't think that GM has called it "posi" or "positive traction" in many years. If you look at the window stickers of any newer car it will say "Limited Slip Differential".

 

A spool would have both wheels spin at the same speed all the time, a locker unlocks around corners making one wheel spin faster than the other unless, it stays locked and the car's back end is hanging out in the other lane hehe

 

Well 'warrior_91', looks like you have all the synonyms for limited slip nailed down, but I'm betting you now want that antonym...right...
They call it an "OPEN rear end"...A lotttt of people get limited & open, confused as being the same...

Ron

 

Not since the mid-70's has it actually been marketed as "Posi-Traction"

 

Stop calling a Limited Slip rear a Posi then.

 

Why? That's what it is. What's in a name? A rose by any other name...

 

cause a lot of people get posi and limited slip mixed up

they think posi is special
and a limited slip is like an open differential


also posi was just GM's name back in the day as was stated many times


now all it is called is limited slip

and what if I am driving around with a quaife style LSD
can't call it a posi-traction anyways


cause posi is GM's name for it
but this wouldn't be a gm style lsd unit so

 

Hmmm, positrac IS special and lets see...third gen F body site...sounds like GM to me...sooooooo its a Posi.:lala: :lala: :lala: :lala:

 

GM RPO code For F-Body cars is G80 which is "LIMITED SLIP REAR".
Even GM calls it Limited Slip now.:lala: :lala:

 

yes but you hit it right

THIRDGEN f body site

hence gm wasn't using that name as others have pointed out since BEFORE the thirdgen came out


also even though this is a GM website what if someone installed an aftermarket system would it still be a posi?

no


posi is an old outdated name

no need for it anymore

also what makes posi so much more special then a LSD?

 

LSD will take you more places than you could ever reach with POSI

 

but posi trac sounds sooo cool. lol

 

You guys forgot the Mopar "Sure-Grip"

Yea, a posi and limitted slip are the same...

"limitted slip" is just the technical term, whereas "posi" is GM's catchy brand name for it.

 

There are three types of rear ends (that I know of)...

The single track or open end - where one wheel and one wheel only, turns. How lame is that.

The common slip or limited slip style diff that puts power to both wheels, but allows for that power to vary from side to side most commonly used in turning. It eliminates one of the tires from chirping or hopping in a turn.

Then there is what I call the True Positive Traction Diff. Not to be confused with the "posi-track" used by (GM) or "trac-lok” use by (Ford). This diff does not belong on the street. It is for race cars . It has no side to side slip. The gears are set, no clutches. And if the input turns "x" times both wheels turn "y" times.

 

Here’s the difference, correct me if I’m wrong.

Posi- positive locking differential. Like (lock right). Actual physical meshing of metal pieces, using spider gears that are spring loaded. Which will override in turns and click to allow wheel speed difference, and fully lock and mesh on straight aways allowing full power to both wheels.

Lsd- limited slip differential. uses clutches and medal plates with springs, when wheel speed differs, spider gears will override and springs will expand allowing clutches to not rub on one another to smoothen out the power from one wheel to the other. When on straight away, springs will shut, and clutches lock with metal plates allowing power to both wheels. kinda like the clutch and pressure plate in a trani. that’s what 8.8 traction locks are.

there’s also worm gear set ups like the true trac, and wave trac. which are like Lsd, but uses worm gears to do the same thing.

 

All are variations of a LSD (LIMITED SLIP). They are called by whatever name the maker can think of, but they still are Limited Slips.

 

your wrong, they are not variations, there are no clutchpacks in a posi rear, posi rears have spider gears that do not slip , they cant, its impossible. they a meshed together like the wheels in a can opener. Limited slips have ctutches that slip back and forth to each wheel, hence the name (limited slip).

 

Limited slip traction or potitive traction is not a name a maker thinks of, it is a defination of a movment of a mechanical mechenizem. and how it operates.

 

He tried. You didn't listen.

 

Those are lockers. Posi does not refer to lockers, it refers to limited-slip.

 

There are several different methods of creating a limited-slip differential. You have cone carriers (9-bolt), clutch pack setups (10-bolts), Zexel Torsen setups (10-bolts), etc etc etc.

They're all limited slip differential carriers. If they were all around in 1970, GM would have probably called every one a "posi", but marketing jargon for this stuff has fallen out of sway, so they just call them what they are these days - limited slip differentials.

 

I been telln dumb mfs this for 20 years. I had 383 bored from 355 with 411 gears and limited slip. Limited slip means less doughnuts and burnouts. Its meant to leave the line quicc so both wheels move at different speeds to keep the car from just sittn at the line burning rubber instead of gettn down dat tracc. People get factory one wheel mixed up wit limited slip. I argued a mechanic yesterday bout it.?

 

A thread that has been dead since 2003 , with a bit of thread necro in 2011 , and you decide to bump it why ???? I'd like to think today's TGO members are way beyond playing word games with posi / limited slip / etc

 

Old thread, yes, but still relevant, believe it or not. I just had the same argument with a friend of mine a few days ago. He thinks that "Positraction" and limited-slip are 2 different things. He's clueless. By the way, Positraction is not a "GM" term. It's a Chevy term. Buick, Olds, Pontiac, and Cadillac had their own brand names for the limited-slip differential (all GM products). Ford, Chrysler, and AMC also had their brand names for it. I think that nowadays, most manufacturers just refer to it as limited-slip...