It depends on when you are using the 4WD,
If you are only using it when actually needed you won't see much difference.
If you are using it regardless of road conditions then you will see a
drop in mileage, HIGHLY increased tire wear and possible damage to the
front axle or transfer case.
If you have auto 4WD then you won't see much of a change until the
clutch unit in the front differential fails, then it will cost you
500.00 or more to get that repaired.
The big difference that people talk about in the 2WD vs. 4WD debate is
if the vehicle is 2WD or 4WD. The 2WD will generally get 1-2 mpg better
mileage because it isn't dragging around the 4WD hardware. This margin
has been getting slimmer over the years due to better engine programming
and drive train designs but it is still valid.
I travel back roads, all snow covered though not deep snow, very windy
roads, usually driving 35-40mph... I have new tires on it, but with the
snow packed roads if I drove in only 2WD I'd be going a max of 30mph to not
be sliding around the turns. I can't just keep it in 4WD for the better
traction all the time?
Snow covered? Then, Yes you can keep it in 4WD all the time. BUT
remember that you may be able to go faster, BUT you cannot STOP faster.
35-40 is about as fast as I would go in 4WD on a straight snow covered
road. On curves I would slow down. 4WD is GREAT at getting people stuck
and even better at causing accidents because people tend to overdrive
the brakes. Want to see how easy it is, Pick a straight stretch of snow
covered road. (Parking lot that is WIDE OPEN is better) Now drive along
in 2WD and do a panic stop. Now do the same thing in 4WD. You might want
to bring clean underwear alone on the test....
Okay, well 35-40 on a straight stretch probably slowing down to 30 around
tighter turns. As far as doing damage to the truck driving in 4WD all the
time, how does the truck know if you are driving on dry pavement vs. snow
packed road? Snow packed, not loose or deep snow. How about trucks that
are in full time 4WD because they come that way? Wouldn't they have damage
done to them as well, or are they just made differently in that case?
The vehicle doesn't know what it is being driven on, its just a dumb
machine. Take your truck to a snow covered parking lot and do a gentle turn
full circle, then move a bit and do a tighter circle, then do a couple
S-turns. Get out and look at the difference in the tracks between the front
wheels and the rear. The arcs are different, the distance traveled is
different. On slippery surfaces the tires can "slip" to compensate for this
at lower speeds, on dry pavement they can't so the drive line binds and the
transfer case gets beat to snot along with suspension mounts, drive shafts
and u-joints. They also have the same problem at higher speeds on slippery
surfaces.. Now then AWD or full time 4WD the transfer case has what amounts
to a differential in it to compensate for that difference in track. My
favorite transfer case was the Quadra-trac that Jeep used in the 70's and
early 80's, it went a step further, the diff in the transfer case was a
limited slip device. If the rear wheels broke traction it would feed the
power to the front axle even if you weren't locked in to all wheel drive.
made it hard to get stuck, down side you couldn't power slide it, as soon as
the rears broke traction the fronts would grab and the truck would
straighten out which took some of the fun out of driving it at times.
And as has been pointed out, it doesn't matter how much more foreword
traction you can generate by locking it in 4 wheel, you still cant stop any
faster, and you will slide off the road in curves at the same speed you
would in 2 wheel drive. Not only that but if one wheel does find a bare spot
of pavement, your more likely to end up sideways in 4 wheel drive.
I got stranded in Cortez Co one time for three days waiting for Colorado's
lousy highway department to plow Colorado SR491, and they left more snow on
the road then they moved. Four of us chained up, and locked our drives in,
three pulling 53' boxes, the fourth a flat bed. It took us almost two and a
half hours to reach the Utah border, which was only 50 miles. Utah knows
how to clear roads. We passed more than a few 4x4s in the ditches, two or
three that had blown by us. Life is too short to be in a hurry when the
roads are slick. Don't end up like the Marquis of Evermonde from "A Tale of
Two Cities" with a note on his body "drive him fast to his grave"
That is a good write up.
For the OP. if you want to find out what WL is saying take your vehicle
to a dry paved parking lot. Put it in 4WD HI and turn left or right into
a circle. You will notice that the vehicle will hop and you might even
hear the tires squeal as they grab and break loose. DON'T DO IT LONG.
That is the result of drive line binding. As pointed out it does nasty
things to the drive train.
In the older vehicles with AWD there is a third differential installed
in the transfer case that allows the system to work. In newer vehicles
this is done with either a differential or a viscous coupler which also
allows the system to slip internally.
When you go around a corner, the outside wheel travels farther.
Inner, less far. this tears up front gearboxes if you do it on
That's how the truck knows.
I learned on my last truck, to make the switch from 2WD to 4 WD
standing still, in neutral, and with the brake on. I didn't know
that -- and ripped the guts out of my gearbox, in my ignorance.
Christopher A. Young
You can't shout down a troll.
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