GRM Review: Muddin' in a Grand Cherokee

Can electronics work as well as live axles and lockers? We took a 2012 Jeep Grand Cherokee off-road to find out. Click through for car porn.

http://grassrootsmotorsports.com/new-cars/2012-jeep-grand-cherokee-overland-summit/

I've not read it yet, but I'm going to say no.
I've personally seen issues where the electronics get confused and leave a MB SUV sitting in sand, no tires moving.
Then there's the long-term reliability. But having said that, I can't wait to read it, being a Jeeper and a GRMer, my pants are getting tight just thinking about it.

I was certainly surprised! They work much, much better than I ever thought they would. However, I still found myself missing my Trooper on some obstacles.

I'd say this Jeep's biggest weak point is its tires, I don't know how or why they call them all-terrains; they simply aren't!

Oh, and no, that muddy puddle isn't all that we took the Jeep through. It was just the most photogenic spot. We also explored some thicker, muddier stuff.

I'm editing the video now.

I can't wait to see the video.
I'm a little confused though. Why are you biased against Jeeps because you own an Isuzu? I don't think there are many people that would argue Jeep has the most storied, and successful history in the history of civilian 4X4's (and military 4X4's for that matter). Any company that wants to make a capable 4X4 puts Jeep at the top of the list as they've remained true to what they set out to do from day one.
That get's my respect. Heck, if Jeep (AMC) didn't make the Grand Wagoneer, would your Isuzu even exist?
In the interest of full-disclosure, I'm a Jeep nut. But I also pine for a Scout, 1st gen bronco, hummer (real one, not an H2 or 3), 4Runner and lots of other stuff.

I wouldn't read too much into that. I think it's just a matter of, once you're invested in one particular vehicle, you become slightly biased against similar vehicles of other marques by default.

^Exactly. I like Jeeps, and I've even been looking at CJ5s lately. I don't have any hate for Jeep, I just know my Trooper is better.

Yeah, I didn't want that to come off as being offended or anything. I was actually curious if it's what you're talking about Luke, or if Tommy drank too much stale gasoline as a kid

Luke wrote: I wouldn't read too much into that. I think it's just a matter of, once you're invested in one particular vehicle, you become slightly biased against similar vehicles of other marques by default.

Additionally, it can be construed as totally bogus when a manufacturer heaves you something that's marketed toward your interests when the marketed purpose is predominantly hype. "Hey, Miata crowd! Try this Lesabre! You like Ginzu knives? Buy this box cutter!" I take my Subarus down dirt forest roads too, doesn't mean I'm ready for stage rally or Moab.

I read Peterson's 4 Wheel and Off Road for years, it was sad to see the decline of actual trucks into tarted up wagons with little on OR off road ability. Towards the end, it was solely the awesomeness of Rick Pewe that kept me buying the rag.

Very well written, young Suddard!

ValuePack wrote: Additionally, it can be construed as totally bogus when a manufacturer heaves you something that's marketed toward your interests when the *marketed* purpose is predominantly hype. "Hey, Miata crowd! Try this Lesabre! You like Ginzu knives? Buy this box cutter!" I take my Subarus down dirt forest roads too, doesn't mean I'm ready for stage rally or Moab.

The same applies to dealers. A little over a year ago before I got my 08 Si I stopped on a used car lot looking for a manual Legacy Wagon. The salesman kept trying to push a Toyota Matrix on me, saying "just drive it, just take it out for a drive". I refused repeatedly which at that point he said "it probably drives better than that" referring to the 08 Speed3 I was in. My response was that it probably did but I still wasn't interested.

Interesting to read about the use of brakes to simulate a faux locked slip differential. My old Ford 8N tractor was made this way. The brakes were manual side to side, and the owners manual instructed you to dance on the pedals to control wheel slip side to side. Didn't work worth a darn, as well evidenced by the threads on old tractor forums. Perhaps the Jeep makes it work because of reaction speed.

Wait – the car wash wouldn't take you because the Jeep was too dirty?? Florida really IS weird. Up here, car washes wash dirty cars.

Meanwhile, about the rock sliders: I think Jeep is, you should pardon the expression, between a rock and a hard place on this one. One thing they really don't want to do, as a company, is tick off their aftermarket, so leaving stuff like rock sliders for the vendors makes good tactical sense. Secondly, everybody who cares enough to know what rock sliders are probably has his/her idea in mind of what the perfect one looks like, so as soon as Jeep puts one on from the factory it instantly disappoints everybody who doesn't like that particular style. (And you can imagine the Internet buzz as soon as somebody starts dissing the new OEM rock sliders, which soon transmutes into "the new Jeep isn't any good off road.") And rock sliders probably act as rust traps (especially if nobody will wash them...), which messes with the corrosion warranty. And, anyway, what percentage of actual Overland owners ever go further off road than the unpaved parking lot at the landscape centre?

Bottom line: it's all about money. You may have noticed over the weekend that there's a lot of money involved in this business.

But Jeeps are Trail Rated(tm)!

Tom Suddard wrote: I'd say this Jeep's biggest weak point is its tires, I don't know how or why they call them all-terrains; they simply aren't!

You read the sidewall wrong. They're mall terrain tires.

I don't believe electronics can do the job of lockers. A good diff will essentially add traction, while electronics will only manage the traction you have. Around here, you need low speed creepin' ability. A bit of time off-road in the company of a new, stock Disco II (obviously, about 8 years ago) showed the problem with an electronic traction setup that needed 1800 rpm or so to kick in. It needed to work from idle.

As for "too dirty" - in Colorado, people use car washes to clean off their elk carcasses. That is unpleasant.

Electronics can. The jeep doesn't just jam on the brakes like a traditional system. Instead, it applies gentle pressure so both wheels on an axle rotate at the same speed. This does imitate a locker quite well. However, the system can overheat, and it can't really keep up with constantly changing traction levels. It's great for when one wheel is in the air, but not so great for other stuff.

At the risk of sending the thread on a tangent:

I just had an idea. One of the things that fascinates me about modern engine tuning is stuff like Megasquirt. The fact that you can build your own ECU, plug up a laptop, and command, "You mix it like I tell you to!" across the whole rev range just amazes me.

Is it too far of a stretch to imagine dedicated off-roaders doing something similar to electronic traction control? If a human designed it, a human can hack it, right?

Then there's the long-term reliability.

electronics dont have metal to metal contact so they are vastly more reliable than anything that happens in a differential.

it was sad to see the decline of actual trucks into tarted up wagons with little on OR off road ability.

What trucks are you talking about? Stock trucks? Because, like the minivan thing GRM did a while back, a new stock truck will blow the pants off of an old one on-road (and likely most old cars too), regardless of what it does off-road. It wasnt THAT long ago you could easily flip a stock truck just by sawing the wheel back and forth on the highway (like an isuzu trooper, and consumer reports has nothing to do with that FACT). Add a lift and big tires to the mix and you're likely making it worse, along with ALL its other on-road attributes like stopping before it runs into things. Now, if you're only talking about modded trucks, i still say they probably dont have LESS on-road ability now than they ever did before.

A good diff will essentially add traction, while electronics will only manage the traction you have.

That makes no sense.

friedgreencorrado wrote: At the risk of sending the thread on a tangent: I just had an idea. One of the things that fascinates me about modern engine tuning is stuff like Megasquirt. The fact that you can build your own ECU, plug up a laptop, and command, "You mix it like I *tell* you to!" across the whole rev range just amazes me. Is it too far of a stretch to imagine dedicated off-roaders doing something similar to electronic traction control? If a human designed it, a human can hack it, right?

It's easier to just put in a nice locker or LSD and be done with it. And the ABS trickery can work. Twice I've been stu.....momentarily delayed in a Jeep. I had one tire that wasn't getting any traction at all. I put the e-brake on about 1/2 way. The brakes put drag on the axles, evening out the traction. Drove right out of there. The first time I forgot to release the e-brake. I smelled the burned brakes a little while later....

Vigo wrote:

A good diff will essentially add traction, while electronics will only manage the traction you have.

That makes no sense.

Yeah, I go back and forth on believing myself there too. I guess if you've only got X traction available on one wheel and Y on another, that's the limit of how much traction is available regardless of how the drive is distributed. I just have a mental block about putting on the brakes as a matter of course to limit power delivery to one of those wheels. As a last-ditch thing to deal with a hanging wheel or a bad failure to proceed, sure.

As for electronic reliability vs mechanical, maybe I spend too much time with off-roaders. But if you fill a diff with water, you just need to drain it and refill the fluid. Fill a box of electronics with water, they're usually not so happy :) Same with yanking wires and sensors off when you're dragging your wheels across rocks and getting sticks tangled up in them. I'm all for electronics in a track car, but an off-roader needs to be armored well.

As for electronic reliability vs mechanical, maybe I spend too much time with off-roaders. But if you fill a diff with water, you just need to drain it and refill the fluid. Fill a box of electronics with water, they're usually not so happy :) Same with yanking wires and sensors off when you're dragging your wheels across rocks and getting sticks tangled up in them. I'm all for electronics in a track car, but an off-roader needs to be armored well.

Looking at it in that specific way, i actually agree with you. Just because the electronics themselves are reliable doesnt mean they are always well protected from external damage.

I miss having a GC as my DD. Loved that sucker.