On Tue, 28 Oct 2014 09:28:23 +0000, Roland Perry
wrote:

In message

, at 04:47:11 on Mon, 27 Oct 2014, Recliner
remarked:
If you want 75% of the power put on the road through the left wheel,
and 25% through the right wheel, how does braking the right wheel
achieve that without absorbing some of the engine power?

It will need to apply a small force to the wheel, but I can't see why
it would absorb any significant power as that would just go to the
other wheel via the diff.

That sounds fine if you aren't attempting to put any power on the road
through the 'spinning' wheel. I'm looking at the case where you want
about half the power that would otherwise be sent through the rubber to remain.

With ASC, you would be putting some power through the wheel that would
wastefully spin with a locking diff.

If the diff is locked both driving wheels rotate at the same speed. If
one is spinning, very little power is "lost" - the only place it can be
dissipated is warming up the tyre/road surface and if slippery/icy
that'll be very little. The rest of the power inevitably goes to the
wheel with grip.

Agreed, but the opportunity is also lost to put some limited power
through the wheel with low adhesion.

But the key thing is you can't have a locked diff on a normal road
car, as it would ruin the tyres and make the car undrivable on curves.
Off-road vehicles can usually lock the centre diff and possibly the
rear diff, but that's a conscious decision taken when driving
off-road, not a default setting. So if a car unexpectedly hits a
slippy patch, even cars with lockable diffs will be unprepared. But
ASC is ready and waiting to spring into action at all times.