Useful article
New Land Cruiser gets V-8
Lindsay Brooke
Automotive Industries Feb. 1998
Design/Engineering: Chassis
Design of UZJ100, as the '98 Cruiser program is coded, was frozen in mid-1994, says veteran chief engineer Takeo Kondo. At that point, the previous FJ80 model was three years old. And as on every previous Cruiser, UZJ100 has body-on-frame construction.
"There was never any consideration of unibody design," Kondo tells AI. "Long-term durability has always been the number one goal of the Land Cruiser program," he explains, "and we expect these vehicles to be on the road for at least 25 years." Range Rover was the program's primary benchmark, particularly for suspension articulation, chassis stiffness and interior appointments.
Kondo's team completely re-engineered the FJ80's ladder frame, adding three extra crossmembers (now nine) and beefing up the side rail structure. Each crossmember is set into the rails using new bracketry, which Toyota calls a flared-flange-type joint (see Illustration). Frame rail wall thickness has been increased to 3.2mm, and the boxed rails include internal stiffening plates welded within their front 48 inches. Kondo claims this helps maintain frame integrity during a frontal impact, keeping the front end from "folding up" into the passenger compartment.
Kondo says none of the Cruiser's frame components is hydroformed nor does any Toyota program currently use this increasingly popular method of metalforming (see June '97 AI, p. 57 and Dec. '97, p. 40). The new frame surpassed the benchmark Range Rover frame in bending and torsional rigidity, claims Kondo (he did not reveal actual frequencies), while boosting overall rigidity by 5096 versus the old FJ80's frame. The stiffer frame allows more compliant suspension bushings and body mounts, helping to improve the new Cruiser's ride comfort. Two types of body mounts are used: compression and lateral-restriction.
The '98 Cruiser switches to an independent front suspension (IFS), based on upper and lower control arms and longitudinal torsion bars. The latter mount to a frame crossmember via a floating member designed to control fore/aft stability of the EFS and limit road-induced NVH. For the vehicle to match its go-anywhere image, all critical running gear, including suspension lower control arms, mounts high. The rack-and-pinion steering gear mounts above the front crossmember, which also protects the engine oil pan and radiator. Both torsion bars are protected by a large skid plate. Minimum ground clearance is nearly 10 inches, and the Cruiser's suspension stroke is among the industry's longest: 200mm front, 240mm rear.
The new Cruiser's Aisin-supplied ABS operates even in 4-wheel low while the center diff is locked. The system is able to "read" road conditions and vehicle dynamics, decreasing the amount of anti-lock applied according to suspension travel, road gradient and abrupt changes in vehicle speed. Foundation brakes feature 4-piston calipers and 12.2-inch ventilated rotors in front, and huge 12.9-inch rear rotors.
Design/Engineering: Body
Also improving the overall structure, and the body's dimensional accuracy, are new one-piece bodysides, claimed by Toyota to be the largest on any light vehicle. The large panels replace the FJ80's two-piece welded bodysides. High-strength steel reinforces all pillars and door sills. Door and rear liftgate jambs are wider for improved ingress/egress and cargo loading.
Dynamically, the UJZ100's structural changes have wrought a vehicle devoid of any body flex or squeaks when flung over the roughest terrain we could find at Borrego Springs, a California desert off-road park that's far more amenable to motocross bikes and extreme dune buggies than luxury SUVs. Driven back-to-back versus a '97 FJ80 over washboard dirt roads, the '98 Cruiser's NVH attenuation is noticeably better. Toyota has added more melt-on asphalt sheeting to the floorpan, and has increased the amount of sound-deading urethane foam and pads injected into pillars and roof rails. On the highway, wind noise is lower due to faster (by three degrees) A-pillars, and new flush-mount windshield and rear quarter window glass.
The extra stiffness and refined manners come at a price, however--mass. The new, all-steel-bodied Cruiser weighs nearly 500 pounds more than its predecessor, mostly due to the chassis and body upgrades. Kondo says there was no plan to offset the added mass with lighter weight components, such as aluminum body panels. At nearly 6,500 pounds GVWR, the Cruiser is actually a medium-duty vehicle.
Powertrain: New V-8
Land Cruiser finally gets a V-8 (a first for any Toyota-badged vehicle), but the new 4.7L engine does not contribute to the new model's extra heft. Even with its cast-iron cylinder block, the dohc, 32-valve V-8 weighs 66 pounds less than the FJ80s 4.5L inline six.
Program boss Kondo admits he wasn't initially sold on the V-8. "We evaluated the (Lexus) aluminum-block car V-8 early on, but it did not have enough low- and midrange torque for our vehicle," he recalls.
So he chose displacement. The UJZ100 design spec required an iron block, with extensive ribbing for bulletproof durability. Manufacturing efficiency called for the Cruiser's block to be machined on the same Tahara plant line as the 4.0L Lexus car V-8. Thus both blocks share common bore centers, but the Cruiser's has the maximum displacement permitted by the Tahara line. The 94mm bore is 6.4mm larger and stroke, at 83.5mm, is 1mm longer than on the car V-8. Besides its iron block and more displacement, Toyota's new "truck V-8" also differs from its car cousins in combustion chamber shape (though valve angles are the same as the 4.0L), cam profiles, and intake manifold geometry. It has a stouter crankshaft, and the con rod big-end bearing shells are aluminum. Package efficiency was also critical; the V8's designers placed the water pump and starter motor inside the block's "vee" to save space.
Powerful 32-bit engine control and effective catalysis, plus Denso top-feed injectors and coil-on-plug ignition, help certify the new Cruiser as a Low Emission Vehicle (LEV) in California. Claimed output is 230 hp at 4,800 rpm, and 320 lb-ft of torque at 3,400. That's a boost of 18 hp and 45 lb-ft over the old inline 6. At presstime, city/highway fuel economy was estimated at 14/16 mpg, more frugal than with the six This basic V-8 will also power the '99 T100 pickup, although rumors persist that the T100 engine will have sohc cylinder heads.
As fits a true 4A, the '98 Cruiser retains a 2-speed Aisin transfer case (and 2.48:1 low range). U.S. market models only offer a 4-speed electronic automatic transmission, sourced by Aisin A-W, While the center and rear differentials are still (optional) "lockers," the Cruiser's new IFS with torsion bars forced the elimination of the FJ80's locking front diff.
Interior
A slightly wider and longer cabin features a subtly refined IP, and an increased array of storage areas overhead, in consoles and cubbies, and in the door panels. Rear seat legroom is up by nearly three inches, and front seats have almost two extra inches of fore/aft slide. There is also an engine immobilizer, a trio of 12-volt power outlets, and power swing-out rear windows.
Manufacturing
Land Cruisers are made the old-fashioned way. Chassis are fully assembled at Toyota's Honsha plant in Toyota City, then trucked across town to Araco, a Toyota kieretsu affiliate. Araco, which produces the company's Coaster minibus, stamps the massive one-piece bodysides on the largest press in Toyota's inventory. It also builds the Cruiser's body and assembles the vehicle.
RELATED ARTICLE: LEXUS LX470 FEATURES VARIABLE SUSPENSION, HEIGHT CONTROL
While the '98 Lexus LX470 shares its drivetrain and structure with the Toyota Land Cruiser, two chassis systems are exclusive to the Lexus. A variable height feature and adaptive suspension combine to give the luxury SUV an excellent combination of off-road ability and highway comfort.
The Automatic Height Control system consists of an electric pump, pressure accumulator and four frame-mounted gas reservoirs linked to the gas-filled shock absorbers. AHC uses a complicated set of tubes to connect all the hydraulic components. The system features a central accumulator that supplies pressurized gas to the four satellite gas chambers. Each chamber is connected to one of the shock absorbers. The LX470 rises and falls as the pressurized gas is channeled to and from the gas shocks.
A dashboard switch allows the choice of three heights: "Low," which means 8.7 inches ground clearance for the rear axle; "High" raises the LX470 two inches; "Super High" cranks it up another two inches. The suspension defaults to the low setting when the SUV is stationary and whenever the speed exceeds 19 mph. The system will neither raise nor lower the LX470 if any door is open.
The gas shocks also adjust continually to road input. Using the Active Variable Suspension system that bowed on the '97 ES300 sedan, each shock absorber adjusts individually through a range of 16 settings. The LX470's body controller can change the shock setting in as little as 2.5 milliseconds.
