To facilitate my explanation I'll follow the same scenario and the following definitions:
I'll consider all explanation considering the car doing a left curve.
$W_{rL} =$ For Left Rear Wheel
$W_{rR} =$ For Right Rear Wheel
$WD = $ for Welded differential
$LD = $ for Limited-slip differential (btw Torsen is a type of $LD$)
$OD = $ for Open differential
$r_v = $ for rotation speed on the wheel
$L_F = $ for Lateral force (byproduct of the mass of the vehicle)
When you start cornering what makes the car slip (drifting) is the resultant force from the sum of the force from rotation of the wheel and the lateral force resultant from the mass of the vehicle.
In the normal cornering (without drift) the $W_{rL}$ will rotate slower than the $W_{rR}$. And the lateral force will be concentrated on the right side of the car.
The $W_{rR}$ will be subjected to more lateral force than $W_{rL}$.
With $OD$ the car will first accelerate $W_{rR}$ until the wheel start slipping. On this moment almost all the power of the car goes to $W_{rR}$ and your car will desacelerate until the slipping stops (and if you continue accelerating) there will be a loop without never slipping on $W_{rL}$, and so no driftting here.
With $WD$ the car will start the drifting with the same speed on both wheels. In this case the minimum speed to get a true drift will need to surpass the minimum threshold from $W_{rL}$. But the $W_{rR}$ will rotate with the same speed from $W_{rL}$ ($r_v$ is distributed 50% on $W_{rL}$ and 50% on $W_{rR}$). But our lateral force is not the same with let's say $L_F$=20% on $W_{rL}$ and $L_F$=80% on $W_{rR}$ (the correct $L_F$ will vary acording with entry speed on curve and curve angle).
The result in this case is that with $WD$ the tire grip on $W_{rL}$ is better than the grip on $W_{rR}$ because of the inbalance of the sum of the forces.
With $LD$ the car will start drifting first on $W_{rR}$ like with $OD$ but our $LD$ will garantee that some power remains in $W_{rL}$ and the speed keeps increasing until $W_{rL}$ starts slipping too.
The moment the drifting start, the $LD$ will distribute the $r_v$ on both wheels to get a balance in the resultant force. So the values now will be something close to:
- on $W_{rL}$: $L_F$=20% + $r_v$=80%
- on $W_{rR}$: $L_F$=80% + $r_v$=20%
With this combination the grip on the wheels will be the same and no lost power like with $W_{rR}$ like with the $WD$.
Sorry by the lack of images to help the understanding.
I'm new with stackexchange and I need to fiddle more with the commands to learn how to create some helping image and put here.
