Honda Pilot's VTM-4 4WD System on Ice

On Sunday, my sister-in-law was driving her 4WD Pilot up an icy road in
Yosemite. The vehicle skidded on ice, did a 360 degree, and she ended up
stuck slightly off the side of the road, but with no damage. Three
wheels had no traction, and the 4WD system dutifully delivered all the
power to the wheels that had no traction, while the wheel with traction
got no power.

She didn't know how to manually engage the 4WD, since it doesn't work in
(D)rive. Some people came and pushed her out and everything was okay,
but it seems like the 4WD system should be delivering power to the
wheels that have traction, like a limited slip differential on a normal
4WD truck would do, rather than spinning the wheels that have no traction.

Meanwhile, I went up the same road in my Toyota 4Runner, and had the
traction control system engage when I began to slip on the ice, but I
didn't skid. I was thinking of getting a Pilot as the 4Runner is too
truck-like for me, and is uncomfortable for rear seat passengers. But if
the 4WD system is not up to par then I may pass.

You should do a little research on things like: 4WD compared to AWD,
full time AWD vs part time AWD, AWD vehicles that have a locking center
differential(or clutch pack) and those that don't, AWD vehicles whose
AWD shuts off over 25 mph, etc. There are quite a few variations
between car brands and sometimes between model lines within the same
brand. Unless you are going to look at expensive brands like Audi or
BMW you may not be happy with the AWD found on "lesser" brands.

Ken

SMS wrote:
> On Sunday, my sister-in-law was driving her 4WD Pilot up an icy road in
> Yosemite. The vehicle skidded on ice, did a 360 degree, and she ended up
> stuck slightly off the side of the road, but with no damage. Three
> wheels had no traction, and the 4WD system dutifully delivered all the
> power to the wheels that had no traction, while the wheel with traction
> got no power.
>
> She didn't know how to manually engage the 4WD, since it doesn't work in
> (D)rive. Some people came and pushed her out and everything was okay,
> but it seems like the 4WD system should be delivering power to the
> wheels that have traction, like a limited slip differential on a normal
> 4WD truck would do, rather than spinning the wheels that have no traction.
>
> Meanwhile, I went up the same road in my Toyota 4Runner, and had the
> traction control system engage when I began to slip on the ice, but I
> didn't skid. I was thinking of getting a Pilot as the 4Runner is too
> truck-like for me, and is uncomfortable for rear seat passengers. But if
> the 4WD system is not up to par then I may pass.

Kenneth J. Harris wrote:
> You should do a little research on things like: 4WD compared to AWD,

According to the literature on the Honda 4WD system, it should be
delivering power to the wheels with traction when it detects slippage.

It works fine as long as you never encounter the situation where both
wheels on either side lose traction, because it only appears to shift
power between front and rear, but not between sides.

It will engage both rear wheels simultaneously, but if one rear wheel
has no traction, all the power goes to the wheel without traction.
Similarly, the front wheel drive does not have any sort of LSD, so all
the power goes to the wheel with no traction as well.

On some traction control systems, the wheel with no traction will have
the brake automatically applied by the ABS system, so the wheel with
traction will be driven. This is cheaper than an LSD or locker. It seems
as if this would be an inexpensive way to correct the VTM-4 limitations.

Yes--all correct info. I believe the Honda system shuts off above about
25 mph, which is fine for low speed traction in snow etc. More
sophisticated systems operate at higher speeds, and as you seem to
understand, will transfer from side to side as well as front to back.
My take on this is that the Honda system is probably OK for many low
speed low traction situations, but if you need(or want) more, you need
to look at other vehicles. I'm going to be thinking about a new
(probably crossover) SUV at the end of 2007 if I can find what I like.
Besides our Accord(which we will keep) I would like something with at
least the capability of my Mercury Mountaneer, which while not a great
vehicle by any means has a considerably more capable drive system than
the Pilot, in my opinion.

SMS wrote:
> Kenneth J. Harris wrote:
>
>> You should do a little research on things like: 4WD compared to AWD,
>
>
> According to the literature on the Honda 4WD system, it should be
> delivering power to the wheels with traction when it detects slippage.
>
> It works fine as long as you never encounter the situation where both
> wheels on either side lose traction, because it only appears to shift
> power between front and rear, but not between sides.
>
> It will engage both rear wheels simultaneously, but if one rear wheel
> has no traction, all the power goes to the wheel without traction.
> Similarly, the front wheel drive does not have any sort of LSD, so all
> the power goes to the wheel with no traction as well.
>
> On some traction control systems, the wheel with no traction will have
> the brake automatically applied by the ABS system, so the wheel with
> traction will be driven. This is cheaper than an LSD or locker. It seems
> as if this would be an inexpensive way to correct the VTM-4 limitations.

Kenneth J. Harris wrote:
> Yes--all correct info. I believe the Honda system shuts off above about
> 25 mph, which is fine for low speed traction in snow etc. More
> sophisticated systems operate at higher speeds, and as you seem to
> understand, will transfer from side to side as well as front to back. My
> take on this is that the Honda system is probably OK for many low speed
> low traction situations, but if you need(or want) more, you need to look
> at other vehicles. I'm going to be thinking about a new (probably
> crossover) SUV at the end of 2007 if I can find what I like. Besides our
> Accord(which we will keep) I would like something with at least the
> capability of my Mercury Mountaneer, which while not a great vehicle by
> any means has a considerably more capable drive system than the Pilot,
> in my opinion.

It's too bad, because the Pilot is a great vehicle in most respects.
I've driven my sister-in-laws, and it's a much better on-road vehicle
than my Toyota 4-Runner. But it's very common, at least in the Sierra's,
to have icy roads where the ice is in patches on one side of the lane
but not the other. They don't use salt, so ice is a constant problem in
the winter. The plows try to scrape it, but they don't do a great job.

The road where the Pilot did the 360 is in Yosemite, and it's one of the
only two roads where I've ever seen chains required for all vehicles,
though the chain control wasn't in effect for 4WD vehicles at the time.
They often have a ranger at the bottom of the hill turning away vehicles
that aren't carrying chains, including 4WD/AWD vehicles.