Out in the boonies we found a Jeep Grand Cherokee stuck in a ditch running down the road. the left front and right rear wheels were off the ground because of the way the ditch ran down the road. No matter what he tried, he was stuck. We pulled him out and showed him what a air-locker was and why he might want one. Does this happen to stock 4Runners, too?

This is called, "cross-axle" situation. It should not happen with the 4runner's ATRAC system. You just need to keep steady pressure on the gas pedal and ignore ATRAC's blinking lights and annoying noise. It will get you through.

The only time that i would evision this to be an issue IF you're crossing this ditch while going up a steep hill at the same time. In this situation, the torque "transfer" from ATRAC (to the wheel with traction) is not enough to push the 4runner uphill. (Torque transfer is never 100% with ATRAC or anything else not called a locker.)

As for the Jeep GC's problem, this is well-documented. See this thread:

http://www.toyota-4runner.org/showth...s=&threadid=57

Scroll down to midway. I am hoping that the new electronic Variloks are better than the old one!

The Jeep owner said he also get stuck in the snow when both wheels on the same side of the vehicle lost traction. Maybe there should be a sticker on the dash that warns you about these problems.

There is, it says "Trail Rated".

Koz

Given the proper idiot behind the wheel, any vehicle can get stuck in almost any situation.

Not sticking up for the JGC, but you didn't specify which year, model, and 4wd system it had. Depending on the year, I think the GC had at least 3 different transfer case options, Control-Trac (part time), Quadratrac I (full time, single-speed) and Quadradrive(full time, two-speed) If it was a part-time transfer case model, then what you describe is exactly what I would expect. (They had limited-slip rear diffs, but it's not very effective)

The 4Runners have essentially the same 4WD system across all trim packages for the 4-gen, which should get them out of that situation. But like I said, given the proper idiot.

--Mike

I'd have to see this to believe it. It would be a bad design flaw given the 4runners ability to climb the steepest of hills using only a small percentage of available torque. Traction with just two wheels would be another story.

Don't you mean "Trailer Rated"?

So, when one buys a Jeep GC, the salesperson will explain all the implications of ordering each of the three different systems, and will draw on his/her vast experience in off road operations so the buyer will know how each system fails and leaves one stranded in the outback. I can tell you that posi-traction (insert you own pet name) sucks. A driver controlled locker is the sure way to go. And I don't like all this complication over four wheel drive systems, especially when a salesperson only knows that they don't get paid unless you buy, to hell with what you need, here's the pen... sign.

Traction with two wheels is what is involved when crossing a ditch.

I'll try to be more clear.

Given the huge reserve of torque a 4th gen has even on the steepest of hills, I'd consider it a bad design flaw if ATRAC couldn't make enough torque available to one front and one back wheel to continue the climb regardless of grade. So bad a flaw, in fact, that I'd have to see it to believe it.

Well, i am sure someone has done something like this in the past and can share us a video.

Disclaimer: Hummer H2 may not have the same calibration in it's ATRAC system, but i will use it as an example. According to Hummer literature, the H2 will be able to make up a 10% grade with ONE wheel traction. To extrapolate, i am sure that the H2 can make up a steeper grade hill with two wheel traction, but i doubt that it would be anywhere near 100% grade (45 degree slope).

Well, if you're going to confuse the issue with facts...

Very interesting. Thanks for the info.:

Yep, that's why I own a 4Runner and not a JGC! I liked the idea that I can have the same drivetrain on my SR5 as the guy that buys the Limited. Somehow Jeep got it into their head that if you want full-time 4-wheel drive, you must also want leather seats, and seat heaters, and navigation, and .... well you get the idea. Seemed rather dumb to me that the model with the best 4WD system in their lineup is the least likely to be taken off-road.

And yes, I agree, limited-slip, posi-trac, trac-loc, etc.. diffs suck, that's why my Wrangler has ARB's front and rear.

--Mike

I'm too lazy, but it is possible to calculate how much torque is transfered to the H2's wheel. Any bored physicist around?

I wish Toyota would publish ATRAC's capability.

However, i can tell you that MOST people who buy SUVs these days do NOT do their research on the 4wd system. Think about all those soccer moms out there with Hummer H2, TLC/LX470, or G-wagens. Only a few know how to use it...and a small percentage of THAT group will actually use it once in their lifetime on an actual off-road trail!

Where do you think Land Rover gets their image nowadays?? Or Hummer or Jeep for that matter. If you notice in all of these brands, there is only ONE vehicle that defines the brand...the rest of them just lives under that image. Jeep = Wrangler. Land Rover = Defender. Hummer = H1/Humvee.