Talking about the Active Center Differential Tarmac, Gravel, Snow modes...

With a part time 4WD, if you put it in 4H and start driving and turning on a dry surface it will bind the drive train and screw **** out of it.

In 'Snow' mode the ACD uses more lock up force. I was wondering - is the ACD vulnerable to the same problem if 'Snow' mode is used in the dry? Does anybody have any experience of this?

 

If I'm not wrong, the three settings actually decide how quickly the differential is locked/unlocked when slippage is detected. Maybe it uses more force to achieve speed of locking as opposed to controlling how much torque is sent?

 

I always thought that the way the mitsubishi system works (and the reason why it's so damn effective) is that it's 50/50 all the time and it acts like a 4x4 locked.

The difference is, the moment the car detects that it's in a turn and needs the wheels to spin at different rates (or it'll destroy the drive train), the active differential unlocks. The snow/gravel/tarmac allows the active differential to unlock easier and easier in that order. So it'll "hold" more in snow than in tarmac.

 

Nope. None of the above.

The diffs are never locked. Our traction control uses the brakes and throttle to control wheel spin. The 3 different settings simply change how long wheel spin is allowed before traction control kicks in. Tarmac is almost instantaneous, and snow allows for some decent spinning.

It's actually a very smart system, because locking center diffs, like what subaru uses, have to have clutches to hold one side of the diff solid. Mitsu realized that the wheels all have brakes, so why install crappy ones on the diffs when the wheels can just do it for you. Problem solved, plus we all change our brake pads every so often.

FWIW: AYC controls the rear diffs left to right power distribution. If the car senses a "push" or "under-steer" condition, it drives the outside rear wheel harder. If it detects a "loose" or "over-steer" condition, it drives the inside rear wheel harder.