I told my buddy limited slip was a form of posi. He said I was wrong. He said:

"Limited slip has clutches and springs inside to lessen the chance of one side spinning faster than the other."

"Posi is gear driven, and sends power to the wheel that spins slower"


He's a smart guy, I just don't want to keep bothering him with questions. Any input would be appreciated.

 

an OPEN differential: only the passenger side rear wheel will spin

a LIMITED SLIP differential: both rear wheels will spin the same as long as the front wheels are relatively straight.

a POSI rear end: both rear wheels will spin the same at all times (sometimes also called a locker)

Hope this helps

 

Thanks for the reply. I also did mention that a locked diff is "true posi", and he also said thats incorrect. He said a posi can turn a corner and be fine, where as a locked diff would sqweel the tires at every turn. Which I agree on the sqweeling part.

 

only differance between posi and limited slip is the spelling. limited slip is sort of generic and posi traction is a gm trade name. it makes no differance how it's achieved posi and limited slip are the same.

 

Yup, it's all the same. Positive traction is just GM's name for limited slip. One side spins and the other kicks in to straighten it out. To also let you leave tracks the way it's supposed to be done.

 

Well I guess he has me "technically" when saying they are not the same, due to limited slip having clutches and posi being gear driven".

 

POSI "FAQ"

Q: What is posi?
A: Posi is a rear differential unit that keeps power applied to both wheels as consistently as possible, as opposed to just one wheel in an "open" rear. In general, a posi unit will "lock up" both wheels under power but with reduced power (in a corner) the axles are allowed to rotate independently and thus make going around corners possible without taking all the rubber off your tires. Posi is short for posi-traction, or "positive traction".

Q: What is limited slip?
A: Limited slip is posi, just another name for the same thing. Keep reading.

Q: What is a spool?
A: A spool is a rear diff. unit that is locked all the time. Period.

Q: What about the "Detroit Locker" ?
A: Yet another name for the same thing, although we think the mechanism may be slightly different.

Q: Are there different types of posi?
A: Yes, but they all do the same thing. There are "cone" types, "clutch" types, etc. There are also different levels of "strength" which determines how often a posi unit is likely to be locked up. See next question.

Q: What about chirping tires around corners?
A: Different posi units have different spring loads, some are more stiff (stronger) than others and thus stay locked up more often. e.g. the Auburn PRO unit vs. the standard Auburn unit.

Q: What are some other names for posi?
A: This is the hardest question to answer because it's hard to trace the origins of the "nicknames" from various manufacturers.
GM = Limited Slip and maybe Posi-Traction
Ford = Traction-Loc and maybe Detroit Locker
Chrysler = Sure Grip

 

there are various types of limited slip-diffs....cone type, clutch type, rachet type (a.k.a. locker, or detroit locker) torsion type (uses the fact that a worm gear can drive a reg. gear, but not the other way around), POSItraction was GM's trade name for the clutch style limited slip in the 60's and 70's, it stuck, and is still used today to refer to gm limited slip diff's, but it is no longer offical, as the 7 1/2- 7 5/8" rear end's come factory whith the cheper, less efficant, cone type limited slip diffreantal, to be a trye "posi" it has to have a clutch type...somthing tells me this therad is going to start a flame war...this should be intresting