what is the difference between limited slip and posi traction?

[95Alpine325is]

what is the difference between limited slip and posi traction? what does a manual 95 325is have?

[M3SeRg]

Originally posted by 95Alpine325is
what is the difference between limited slip and posi traction? what does a manual 95 325is have?

I think with limited only 1 wheel spins and the Positive both wheels are spining the car forward... not sure though..

[Matthew C Smith]

nope, they're the same thing. Posi is usually an american term. Muscle cars would have posi for example.

Limited Slip is usually a japanese or european thing.

[UD///M]

Both answers are wrong. Limited slip allows both wheels to receive power in a "limited" fashion but also allows each wheel to turn at a different velocity for turning. When one wheel starts to slip, a percentage of the applied power will be transferred to the non slipping wheel.

Positraction is a solid axle. This is not to be confused with the single piece rearend as found on trucks and most american RWD cars. Positraction does not have a differential action. Both wheels turn at the same velocity at all times. Even in a corner. This setup is excellent for drag racing but is horrible for turns and slipery roads.

[95Alpine325is]

so do all bimmers have a limited slip differential?

[UD///M]

No. I believe that a limited slip was an option on all models except the M cars where it was standard. It might also be standard on the 5 and 7 series.

[95Alpine325is]

what would a bimmer have if it didnt have the optional limited slip? would there only be one drive wheel on my 325is if it doesnt have limited slip?

[UD///M]

Yes.

[Jim O.]

If it doesn't have the limited slip, then it has an open diff. Here's a link that does a great job of explaining the differences between an open diff and a limited slip:
http://www.howstuffworks.com/differential.htm

Jim

[Jim O.]

Originally posted by UD///M
Positraction is a solid axle. This is not to be confused with the single piece rearend as found on trucks and most american RWD cars. Positraction does not have a differential action. Both wheels turn at the same velocity at all times. Even in a corner. This setup is excellent for drag racing but is horrible for turns and slipery roads.

Sorry, but I think you're confusing a locked diff with Positraction. A Posi is just another term for a limited slip diff. I think it started out as a brand name or marketing term, mostly in the American iron world. Limited slip is the more generic term. Strange thing is that some companies use both terms - for example, Auburn calls their diff the "Auburn Positraction limited-slip differential"...

Also, depending on the car, and the car setup, the locked diff can work very well on the road course or autox. It does require a different driving style, but allows you to put down a huge amount of power really early in turns. If you have a car that picks up a driven wheel, then a lot of times the locked diff will work well - a friend of mine drives a heavily modified Audi S4. In an autox, he picks up the inside rear wheel a lot - because of the way the diffs are setup, once that wheel comes up, a lot of the power gets sent to it, which doesn't do any good. Quaifes and Torsens don't do any good, because they need some load on both wheels to be able to do the torque sensing thing. By going to a locked diff, he can get much more power to the ground, no matter how many wheels are up in the air.

Jim

[Matthew C Smith]

I agree a locked or welded diff is NOT posi

I won't even get into the locked diff issue