Changes in the 4wd system on new Expedition

[powerboatr]

4A has always been capable of 100/0 and is usually 0/100 (full RWD) unless wheel slip is occurring or predicted. It's capable of detecting and reacting to wheel slip within 1/3 a wheel revolution, and even predicting it under certain conditions.

4H would lock it to 50/50, yes.

i was reading at borg warner and it appears the tq on demand system is still whats in the 2018, with some electronics programing adjustments for the terrain settings.
BUT in 4A the front drive shafts and wheel ends are engaged and the transfer case is using viscous clutches to allow for slippage and prevent tq bind.
It also monitors the two driveshaft speeds and thus determines if rear is slipping and will apply tq to the front to regain traction (simple form)
in 4H the system is electronically "locked" and this leads to tq bind...b/w said this makes it so they dont need a differential in the transfer case,
i can tell you from personal exp. you never know its adding tq to the front wheels unless you in really slick stuff, and then 4H is best.
neat stuff

 

[deweysmith]

i can tell you from personal exp. you never know its adding tq to the front wheels unless you in really slick stuff, and then 4H is best.

Yep, I tested it out some at the sand dunes. You can't hear or really even feel it doing anything, but starting in deep sand in 2H and 4A are miles apart. 2H slides quite a bit before finally getting going, 4A doesn't even hesitate. 4H doesn't feel any different either, starting out, but I like how it drives in 4A at speed better than 4H.

 

[jeff kushner]

I have driven both my '99 & my '03EB in 24" snow. I also tend to "have fun" in the snow electing to let the kids drive around the empty school lots or for us to take it on the frozen fields for huge power slides but EVERY time that I ever managed to get them stuck in the snow, laying a comforter in front of the truck, tucking it under the front wheels and snicking it into 4L & let off the brake and the truck would just walk up out of the rut onto the comforter....once past it, just toss it in the back.

I wonder how the '18s will do?

jeff