Black13B

iTrader: (1)

*props to Amur_ for getting the video*

ok so we jacked up the car and spun the wheel.. from what i understand, the LSD makes the opposite tire spin as well..

so watch the video carefully.. towards the end you will notice the opposite one just turn about an inch then stop when i switch directions instead of following through

i was told by a few people already that it's because it's a "limited slip" so it only does both when it has to.. which.. doesnt sound right to me.. but i may be wrong.. to the best of my logical knowledge, both wheels should spin in sync because of the LSD.. you still can see some "torque" to the wheel with the direction change, it just doesnt follow through after the direction.. if you understand what i mean..

pay close attention to the opposite wheel being spun and tell me what you all think..

http://members.rogers.com/thecheat/lsdtest.avi

Center of The Universe

LSD's fuction is when one wheel slips, the power gets transferd to the wheel curently undertraction. if you hit, let's say...dirt. LSD is ment to strighten your car out, and help you stay under control. (or so they say)

Black13B

iTrader: (1)

so, just raising the car in the air and spinning a wheel is not an accurate test then?

rotary>piston

not really, you need to put more load on it than that.

capsoval

jack the car up. Spin one wheel. If they both spin in the same direction you have a posi. If they spin in opposite directions you have a limited slip or an open diff which just means that there is no clucth pack only spider gears. To find out if its limited slip or open, Go find some dirt, do a brake stand or pop the clucth. If both tires spin you have limited slip, if you do a one legger you have an open diff. Good luck

SureShot

Nice video illustration. You can see, even under light load, they both go in the same direction more than opposite.
What some people miss is that the transmission must be in neutral.

SonicRaT

iTrader: (6)

Posi *IS* limited slip. And limited slip will spin in the same direction, unless it's those damned viscous, then you need to get the wheel spinning faster so it locks up. The best test for this, is one tire on dirt/grass, and the other tire on cement, dump the clutch and see if you can spin both or just 1. That'll tell you if it's working or not.

Center of The Universe

Not really. I think a day at the track would be nice test.

Icemark

Posi, or Posi-traction is GM's term for a LSD, and not really accurate. Sorta like calling all non-OEM air filters an K&N filter.

Anyway, the video show great how to check for a LSD rear end. If he had a open/conventional (or a Torson) rear end the opposite wheel would have turned the opposite direction. On a clutch type or a warm fluid type the wheel starts turning the same direction when there is a load.

projekt

i personally hate the word posi, i connect it with things like pushrod and air cleaner

projekt

oh and leaf springs and live rear axle heh.

Black13B

iTrader: (1)

so it is functioning properly?

sirgrantalot

yeah posi brings the "good old boys" of hazard county

props to the dukes, though,

sirgrantalot

yeah posi brings to mind the "good old boys" of hazard county

props to the dukes, though,

sirgrantalot

oops
lol

Icemark

Looks fine to me, but the real test would be to lower one wheel, so that one side is unable to move then try rotating the other wheel. When it locks up the wheel that is still in the air, shouldn't want to move.

West TX RX-7

Aye do a spin out in the dirt. If both spin it's a LSD or (Posi) is only one spins it's open. The LSD is meant to slip some (it has a clutch in it), when you go around a corner one tire will need to spin faster than the other unlike a Spool where both tires are "locked" together. You take a corner and they both will spin the same amount so you will actually be spinning one of them or dragging the other. I've seen guys weld spider gears together to get this effect (for drag race only though)

dr0x

Thats why I dislike viscous. On a thick layer of water (say if you were half way hydroplaning) or on ice, the viscous is going to act like an open dif.