[HighlandPete]

Originally Posted by bailyhill

Highlanadpete

That is my point. The differential cannot generate torque, it can only divide it between the wheels. I think this can be done with braking or it can be done with some sort of clutch arrangement that engages one side and disengages the other. I know what torque vectoring does, my question is how does it actually do that?

Bailyhill

Sorry, misunderstood your question.

There's a clever, but quite complex, double sun and planet gear drive with a clutch pack, one a side for each drive shaft. The closed clutch is (from memory) a 1.1:1 ratio.

So driving with a bit of purpose, sensors (including the steering sensor) feeding back data you are entering or in a bend, closes the clutch on the outside wheel, increasing the speed of the drive shaft on that side of the vehicle, (up to 1.1:1). Clutch slip compensates for the exact wheel rotational differences side to side, or one wheel would have to slip or spin. We understand that slip, as it's similar to the transfer box clutch pack in the xDrive, which moves torque rear to front.

That extra (geared up) wheel speed translates as extra torque to the outer wheel. Helps for a more neutral turn in, using the outer rear wheel to help reduce the tendency to understeer.

Shame it is so complex, or we'd likely see it available for less expensive models. The concept makes so much sense for press on driving.

[bailyhill]

High Pete

Yea I climbed under my X3 with x drive, and I don't see any clutch housings on the axles, unless its built into the diff hub. So x drive must use the brakes. Perhaps the Go1 will upgrade to this.

Bailyhill

[HighlandPete]

Originally Posted by bailyhill

High Pete

Yea I climbed under my X3 with x drive, and I don't see any clutch housings on the axles, unless its built into the diff hub. So x drive must use the brakes. Perhaps the Go1 will upgrade to this.

Bailyhill

For the X3...

Performance Control.

The Performance Control distributes engine and braking control to the individual wheels when turning.

Because the outer wheels have to move a longer distance than the inner wheels when turning, the BMW Performance Control intervenes by means of engine output and controlled braking: The outer wheels get more power while the inner wheels get less, maximising traction on each of the wheels. This means that the vehicle practically turns itself, thus increasing driving safety and comfort.

Dynamic Performance Control (as in the X5 M), uses the torque vectoring diff.

[Cortexiphan]

Originally Posted by rallybull

The M5 will be AWD too

No it won't be. It will have an xDrive 'option'

[raysspl]

That's nice. AWD is still fairly irrelevant for majority of folks in the non-snowing Western states.

[fecurtis]

Originally Posted by stvding

Better make it awd and rwd switchable

Reportedly it will be,
http://www.roadandtrack.com/new-cars...r-wheel-drive/

[rallybull]

Originally Posted by Cortexiphan

No it won't be. It will have an xDrive 'option'

Good to know. So the question is that if the M5 can come with a RWD setup, why can't the 550i that has lesser torque.