Performance of AWD

[walkabout]

Full disclosure: I have never owned an SUV or AWD vehicle before, and very rarely drive in snow.  I live in Los Angeles, after all!

 

A few weeks ago I was up at Lake Arrowhead for a weekend getaway and we got caught in a freak snowstorm.  There were maybe 5 to 6 inches on the ground.  I met two friends up there, on in an RWD vehicle, and one in FWD vehicle.  Our cabin was at the bottom of a nasty unplowed hill.  I drove right out with no problem, my friends with RWD couldn't even back out of the spot.  Eventually, we borrowed a snow blower and all vehicles got out.

WHat surprised me was how much the FWD origins of the MKX (which, let's face it, is basically a Ford Fusion wagon) came into play.  I got into a few situations where the back wheels were on clean pavement and the front wheels had little traction. In those cases, the vehicle wouldn't move.  My experience was that I didn't need rear traction to keep going forward, but the car got stuck when the front wheels were in trouble.  

 

As an example, I was coming up over the hill that I had plowed via snow blower, and then my front wheels hit an unplowed road in front of me.  rear had perfect traction, front had little.  I could managed to go forward, but when I tried to back up (to avoid an oncoming vehicle), the car was stuck.  Conversely, when I entered the hill at the bottom, I was briefly in a situation where the front was on clean pavement and the rear under snow - no problem.

 

So, to me, it felt like it was the front tires doing all the work.

Thoughts? 

[fredluke]

In Canada the MKX is only avail. in AWD for obvious reasons.

 

I have never been stuck YET... but there is always a first time. My understanding is that wheel sensors determine which wheels are turning and which are not thus delivering torque to either the rear or front. As an example If the vehicle sensors record front slippage it will deliver torque to the rear and visa versa. I think the MKX is virtually a FWD vehicle but calls on the rear drive when needed. If the MKX had no forward motion because either the front or rear wheels were in snow, AWD would be useless.

 

 

Am I wrong? Any mechanics or engineers want to chime in?

[walkabout]

That's how I understand it too, Fred. Traction is definitely better under the front though (at least from my experience).

[Rural_OC_MKX]

Have any of you with AWD watched the screen on the left side of the instrument panel (I forget which sub-menu selects it). At least the display indicates that AWD is enabled for all acceleration from a stop. Is this real or propaganda, I don't know. 

[enigma-2]

I've attached a copy of the September 2009 article of Gear Magazine. It describes in detail how the Ford AWD system works.

Emailing Ford's All-Wheel Drive 2009.pdf

[NOTMY911]

Have any of you with AWD watched the screen on the left side of the instrument panel (I forget which sub-menu selects it). At least the display indicates that AWD is enabled for all acceleration from a stop. Is this real or propaganda, I don't know. 

 

 

Its real...

[fredluke]

Yes...I turned on that screen and surprisingly the torque shifts from FWD to AWD at different driving conditions on dry pavement.

 

If it is accurate- it showed torque delivery shifts when turning corners, or on ramps, downhill, uphill, whatever. Sometimes the vehicle accelerates from a stop at 80% RWD 20% FWD and visa versa. It seems to me that the system is sensing, calibrating, and delivering power based upon traction and stability control continually.

[akirby]

It uses steering angle and yaw sensors along with throttle input to shift torque before slippage occurs.