"Bob La Londe" wrote in message
...
On 5/5/2011 8:44 AM, Stormin Mormon wrote:
At 70 MPH, you'd have no reason to engage 4WD. You may be
grinding gears, there.

On my Chevrolet, 4WD is only used on sand, snow, and
surfaces which have some slip. My 1998 model is "engage on
the fly". My earlier 1989 model would only engage standing
still, with transmission in neutral.


Had to use the 4WD on my Chevy on the street a few months ago. Stop light
on a hill in the rain. Hadn't been raining long enough to wash clean yet.
I just sat there and spun the rear wheels until I kicked on the 4wd.
Thank goodness for push button shift on the fly 4wd.

Anyway, he is talking about an always on or full time 4wd. Dodge had some
trucks that were always on limited slip 4wd. Porsche makes some always on
AWD. I think all Subarus are always on AWD. Lots of other mfgs do.

I don't know first hand, but I have heard that AWD tends to stay in
control better when you get a sudden unexpected surface change... Its not
a miracle cure, but if you aren't running on the ragged edge already it
can save your bacon on things like black ice.

It gives you better control under almost all conditions. When Audi came out
with their system in 1980, they immediately started winning most of the
international rallies in sight under all kinds of road and weather
conditions, from deserts to dry roads to icy mountain roads.

Those systems have evolved over time, and have had different schemes for
apportioning torque. They are very effective today, and have been for a
couple of decades.

--
Ed Huntress