Why a Lexus? Well, the 2011 Lexus GX 460 is based on the Land Cruiser Prado, a smaller version of the Land Cruiser we know that Toyota sells elsewhere in the world. Furthermore, it comes with something called a Kinetic Dynamic Suspension System (KDSS,) a long way of saying it has front and rear stabilizer bars that automatically decouple to improve off-road articulation.
Standard on the GX since 2010 (and optional since 2004), KDSS is also found in the US on the Land Cruiser (2008-present) and the 4Runner Trail Edition (2010-present.)
Daily driving benefits greatly because such a system allows the GX to be fitted with much larger stabilizer bars than any off-road vehicle could otherwise tolerate. Indeed this Lexus GX460 corners far flatter than other SUVs of similar size and configuration.
KDSS is a hydaulic system that's fully automatic -- there are no switches on the dash because there is no need to turn it on or off. Instead, the front and rear stabilizer bars feature hydraulic cylinders on their left-hand sides, with piping connecting the two and a valve in between.
In a corner, both cylinders are squeezed (right turns) or stretched (left turns) in the same direction. Such "in-phase" loading produces front and rear pressures that are more or less equal, which holds the valve closed to keep those cylinders absolutely rigid so the stabilizer bars can deliver their full roll-resisting effects.
But frame twist off-road conditions -- and our RTI ramp -- produce positive pressure in the cylinder that's being compressed and negative pressure in the one being stretched. Such "out-of-phase" axle articulation causes the valve to pop open, which makes the cylinders go limp and take the stabilizer bars out of the picture.
But the stabilizer bars are not cut in two; they're still one-piece hunks of bent metal. When rigid, the cylinder is merely a link holds the pivot bushing in space, much like the rear stabilizer bar setup on a Ford Mustang. But here the open valve allows the cylinder to expand and contract at will, allowing that pivot bushing to float around and prevent the stabilizer bar from generating any torque.
The system works the same up front, where the front cylinder (yellow) allows the left hand pivot point to float when the going gets rough. An obvious notch in the skidplate hints at the amount it can move.
And check out how the end of the humungous stabilizer bar (green) bar plugs neatly into a bushing that's bolted directly to the lower control arm -- just like my 1957 Ford wagon.
The trouble with the GX 460, off-road-wise, anyway, is the way the bumper is encased in plastic like a Camry or Highlander. This one single wraparound piece, which extends all the way up to the taillight, also contains molded-in rear mudflaps. Rub any of this on a rock (likely) and you could do some damage.
Of course none of this matters to the original owners that don't dare scratch their precious Lexus off road, but it'll make this otherwise-capable 4x4 less desireable in the used market ten years out.
What's all this good for? Some 20.2 inches of wheel lift, almost 2 inches MORE than our unmodified 2012 Jeep Wrangler Sport 2-door managed and only a quarter-inch less than the Jeep with its big tires fitted.
But the wheelbase here is over 14 inches longer, so the RTI comes out a little lower: 538 for the Lexus GX versus 561 for the stock Wrangler. Stiil, that's not bad.
What sort of RTI would the Lexus manage with the KDSS turned off? That's impossible to measure because the system is always on. In past years (before 2010) KDSS was an option, and a GX without it had smaller stab bars to allow decent articulation -- but not so small as to allow too much body roll on the highway. This classic off-road trade-off is the main reason why some body-on-frame SUVs -- the more off-road capable ones, usually -- feel queasy in corners.
I'm guessing a non-KDSS GX would ramp about 100 points less. Maybe we'll get our hands on one and find out.
brn says:
03:58 PM, 01/19/12
I'm a little impressed that any Lexus would articulate like that. Try that with an Infiniti.
miamifan1 says:
07:17 PM, 01/19/12
That is some incredible articulation for any regular SUV. Moreso a luxo-barge like this.
Great post - enjoyed the lesson on the newfangled trick bars.
ag4 says:
11:20 PM, 01/19/12
@brn, true and like what they mentioned, this Lexus is actually a LandCruiser Prado elsewhere.
lostboyz says:
03:53 AM, 01/20/12
Wow that thing will be able to crawl over a huge mall parking block.
jeepsrt says:
06:32 AM, 01/20/12
You should try this with the new Grand Cherokee with air suspension. I noticed on mine when in high mode it has no articulation and just lifts the wheel up like riding on fixed metal rods.
blackdynamite1 says:
07:04 AM, 01/20/12
Toyota/Lexus/LandCruisers know off-roading
BD
104wb says:
07:16 AM, 01/20/12
You should add "RTI" as a searchable category. Now what was the JK with the BFGs and stock suspension? How about a 2-dr JK Rubicon with standard 'electronic front sway bar disconnect', or your long-term JK with one front link disconnected to mimic it?
actualsize says:
08:43 AM, 01/20/12
@104wb: I'd like to add an RTI category, but so far I have but one RTI post in Straightline and three in the LT blog. It'll happen though. As for the Rubicon, yes, I need to get a 4-door in here. And we will disconnect the front stab bar soon. We need to spread this stuff out!
fantastic says:
08:53 AM, 01/20/12
Toyota Land C. Prado....i always like them!
bradyholt says:
10:48 AM, 01/20/12
"I'm a little impressed that any Lexus would articulate like that. Try that with an Infiniti."
Well, the QX56 is also an off-road vehicle in other markets -- the Nissan Patrol.
grapesh says:
10:58 AM, 01/20/12
European Prados are more offroad-friendly because they have less plastic that close to the ground.
These massive bumpers look like any amount of offroad articulation for GX in less than perfect conditions with certainly end up at body shop.
desmolicious says:
12:56 PM, 01/20/12
actualsize wrote:
"As for the Rubicon, yes, I need to get a 4-door in here."
I can bring my 2 door 2012 by....
x_defector says:
01:40 PM, 01/20/12
Count me as apparently one of the only ones here who is not surprised! On their native turf, these vehicles are often used as outback overlanders and expedition vehicles. They need this kind of articulation to fulfill their purpose. You see the same in Nissan Patrols, Rovers, etc. Too bad that here they are all clad in plastic that tears off or cracks.
That being said increasing articulation is far from a complicated thing. This KDSS system, although clearly pretty effective, seems way too complicated. Lots of sensors, hydraulic cylinders, boots, lots of wiring...
So much easier to take the Wrangler approach. The driver knows when they need the articulation - a simple swaybar disconnect mechanism that can be electrically activated is much simpler, cheaper, and more effective.
actualsize says:
04:18 PM, 01/20/12
@desmolicious: I may take you up on that offer. We're also thinking of staging an RTI tweetup, or something.
desmolicious says:
05:46 PM, 01/20/12
@actualsize: No problem. The only thing is it would have to be on a weekend.
Work an' stuff..
paul_wmsen says:
12:39 PM, 01/22/12
Great analysis by Dan of why the GX is so surprisingly capable off-road.
paul_wmsen says:
12:40 PM, 01/22/12
Great analysis by Dan of why the GX is so surprisingly capable off-road.