how can i tell a LSD from a normaller Differential

[mischief]

i was at the junk yord and found some 318ti's
found some Differential and many many oder good parts
so how can i you tell whats what

[1996 328ti]

If they have a tab attached that starts with an S then it is a good chance that it is an LSD.

[cali-ti]

they typically also have a white outlined "S" on them (top and/or bottom). if they're removed from the car, turn the drive shaft flange on the front of the diff and both the drive shaft flanges should rotate the same. open diffs will rotate opposite or only one will rotate. if it's ON the car, put it in neutral with the rear wheels up in the air and rotate one rear wheel, the other should rotate the same direction.

[montjuic]

Quick question--when I was doing the brakes pads/parking brake/bleeding last weekend, I rotated one wheel and the other wheel didn't move at all. And
visa-versa on the other side. I've an open diff and on my old 320i and 2002, an open
diff caused the wheels to rotate in opposite direction.

Anyone have an explination why? I'm assuming nothing is stripped...!
cheers,
B

[mischief]

i may of found a LSD i was at the junkyard today and found 2 or 3 diff that might be LSD i did what you said i turned the front the diff and both of the drive shaft rotate the same way

[bimmerboi318]

Well, even if you turn the front part (pinion), the output flanges may turn the same way. I had an open diff for a long time and also had many 2 wheel peels. The best way to tell if its out of the car is to hold the pinion and try to turn one of the side output flanges. If you cant turn it by hand without the pinion turning, it's a lsd....or a severely damaged open diff like my old one haha. And the white "S" on the top is a dead giveaway unless it wore off.