Why a suregrip?
Man....there are a LOT of ignorant people in this hobby.
i hear ya mbaird, but a "posi" unit is 2 wheels pulling. a "limited slip" is one wheel pulling..........i still don't get it.
Uhh, No...not even close. As stated before, the word POSI is short for "Posi-traction". This is a brand name from Chevrolet to describe their limited slip differential that served to equalize traction between the left and right wheels. Once the unit wears or breaks, the drive shaft then only transmits power to one wheel.
Not to be the over corrective a$$hole but Fords term of choice is Limited Slip
And limited slip is both wheels applying power to the pavement... if its a one legger its just a plain old "open" diff
Again, the term "Limited Slip" applies to all differentials that have some manner of function to equalize traction for both rear wheels. Nobody had ownership of this term.
i hear ya 71Duster. i didn't realise ford used that term for theirs. gm used the "limited slip" term for their open rears, and "posi" for their two legged rears....
More ignorance from this guy. NO open differential was correctly called a "limited slip" by any manufacturer.
i don't know if they still do either. so why does everyone always ask if you have a "suregrip"? just why is the "suregrip" rear so good? it is a open rear from what i know of it. why wouldn't everyone want to just put a "posi" unit in it? i know with GM this is the first thing most everybody does......am i crazy or is this just me not understanding?
Every manufacturer that I know of offered some type of differential that served to equalize traction for both rear tires. Most of them did have specific brand names for their differential.
An open differential drives both wheels, but if one of the wheels looses traction then ALL the torque is directed to that one wheel that is spinning. This is what the majority of cars have. These are often refered to as a 'peg leg' rear end.
A limited slip differential is one that 'limits' the amount of torque applied to only one wheel. There are several implementations that accomplish this. One is to use spring loaded clutch discs, a typical example is the Eaton differential. Another way is to use cones instead of the clutches, the example for this is the Auburn differential. Mopar's marketing name for limited slip is 'Suregrip'. And all Suregrips fall into one of these two types of limited slip. Often times these limited slip differentials are called a 'posi', but that is incorrect
Next is the locking differential. This does not use traditional clutches, it use 'cogs' to positively lock the two axles yet still allows one axle to spin faster than the other in turns. This differential is correctly refered to as a 'posi' and the example of this is the Detroit Locker.
In full blown race cars a spool replaces the differential. This solidly locks the two axles together and does not allow either side to spin faster than the opposite side.
There is also a torque biasing differential that behaves similar to a limited slip. These are more common on FWD transaxles.
And there is also an aftermarket device called a Powertrax that can be added to an open differential to make it work similar to a limited slip. The sad thing is they cost as much or more than a true limited slip. However you don't have to disturb the gears to install it so it's easy for the backyard mechanic to set up.
^^^ Finally, someone with brains chimes in to set the others straight. Thank you!
I have always called them all Posi"s all my life and I have always been a Mopar man. We all know what the heck we mean anyway ! Ron
Ron, you're a nice guy but technically, you're using wrong terminology. Do Chevy guys call their 454 a Hemi? POSI is not a Mopar term.
| MANUFACTURER | MONIKER |
| American Motors | Twin Grip |
| Buick | Positive Traction |
| Cadillac | Anti Spin |
| Chevrolet | Positraction |
| Ford Motor Co. | Traction-Lok |
| Mopar | Sure Grip |
| Oldsmobile | Anti Spin |
| Pontiac | Saf-T-Track |
Here is an excellent post. It outlines the specific brand names of what is essentially the same functioning device in different cars.
Yes, we usually know what people mean when they say their car has a POSI even if it is a Duster. For a lot of us, we get tired of GM and Chevrolet getting so much fanfare and attention in this hobby. Personally, I try hard to avoid using Chevrolet terms. I never hear people refer to their 833 transmissions as a Rock Crusher 833. Nobody calls their automatic a Turbo 727. Does anyone ever ask a Corvette guy if their car has a 427 six pack?
