Originally Posted by bimmerjoe
im curiouse at what an open diff is.
and what is my benefit if i get the m5 diff?
That's a very lengthy subject, plenty of stuff around to read about it, but the short of it is that an open differential is essentially a torque splitting device, that always splits torque evenly to both wheels. always. So when both wheels have equal traction, torque is split 50/50 between both wheels. However, it's downfall is that if one wheel looses traction it takes almost zero torque to rotate that wheel, and as a result the wheel that has traction also gets zero torque and the car goes nowhere and the power from the engine is converted into rotational energy in the form of the wheel with no traction spinning like crazy at double it's normal rate.
An LSD on the other hand, in very basic terms puts a preset amount of drag on the output shaft of the diff, so as a result the torque is not equal to zero and power is sent to the wheel with traction as well. It's a little more complex than that when you get into the different types of LSD, but that's the jist of it.
The LSD allows for better use of the available traction, and also allows for better corner throttle control, where an open diff would lose traction on the inside wheel first, and as a result spin it without transferring power to the outside wheel when you get back on the power.