Originally Posted by MatsNorway
Niznai what happens without? and most importantly why?
Not sure what you're asking.
A one way is meant to uncouple drive from one side of the transmission train to another, be it between motor and a pair of wheels or between a wheel and the other on the opposite side. Therein lies the gain (or the pitfall). Wheels can freewheel offpower so they can follow other trajectories than they would were they conditioned by being tied with a belt to the motor or the other wheels, or with a balldiff to the opposite wheel. In practice this translates to the front wheels being able to follow a tighter line around the corner. Sometimes the line is so tight, the rear wheels just can't follow, so they lose grip and the car spins out.
Conversely, on-power a one way behaves like a spool, so it allows no slip at all whatsoever. Hence the powerful acceleration. So much so, that sometimes you can find your electronics/motor overheating and you have to gear lighter than you would with a diff.