[mashimarho]

The AWD in BMW, infiniti, etc VS. AWD in Audi, subaru.
I hear the AWD provided by the quattro and subaru are symmetrical & always running AWD. Whereas, the Xdrive and infinit's AWD only "kick in" when needed in the weaker areas. Does that mean when you're on the dyno only the rear spins? Doesn't all the wheel STILL Spin even though it "kicks in" later?
Misconceptions

[4corners]

Originally Posted by mashimarho

The AWD in BMW, infiniti, etc VS. AWD in Audi, subaru.
I hear the AWD provided by the quattro and subaru are symmetrical & always running AWD. Whereas, the Xdrive and infinit's AWD only "kick in" when needed in the weaker areas. Does that mean when you're on the dyno only the rear spins? Doesn't all the wheel STILL Spin even though it "kicks in" later?
Misconceptions

The front wheels will immediately try to put power down.

[blauner335]

Under normal conditions, x-drive will give you a 40:60 front-rear torque split. The rear of x-drive is always connected, and the torque distribution to the front is controlled by a servo motor that can give a 50:50 split under ideal conditions. The only time the front can have more torque than the rear is when the rear has less traction than the front, then technically the front can put down more torque than the rear. BMW claims it can have a 100:0 torque split, but that's only if the rear tires are on a frictionless surface. There are 3 conditions in which x-drive is RWD:

1. Over 100 mph
2. Severe Understeer
3. If no traction is available at the front wheels

If your front wheels are on frictionless bearings on your dyno, then all the power will be put down in the rear, obviously. But if there is some traction up front, some of the power will be transferred there.

[mashimarho]

Originally Posted by blauner335

Under normal conditions, x-drive will give you a 40:60 front-rear torque split. The rear of x-drive is always connected, and the torque distribution to the front is controlled by a servo motor that can give a 50:50 split under ideal conditions. The only time the front can have more torque than the rear is when the rear has less traction than the front, then technically the front can put down more torque than the rear. BMW claims it can have a 100:0 torque split, but that's only if the rear tires are on a frictionless surface. There are 3 conditions in which x-drive is RWD:

1. Over 100 mph
2. Severe Understeer
3. If no traction is available at the front wheels

If your front wheels are on frictionless bearings on your dyno, then all the power will be put down in the rear, obviously. But if there is some traction up front, some of the power will be transferred there.

that is exactly the answer I was looking for. I was under the impression that xdrive is rwd until it needs to kick in the front, but I'm glad it is constantly 40/60 until change in circumstance.