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Chevrolet Suburban 2500 SUV adds four-wheel steering control
Bob Plunkett
Date Posted: 5/10/2005
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MANITOU SPRINGS, Colo. -- On a crowded parking lot off Pawnee Avenue in the Colorado resort of Manitou Spring, one driver's challenge is to maneuver the multi-ton mass of a behemoth sport-utility vehicle into narrow confines of a conventional parking slot.
It's a problem many drivers face due to the increasing popularity of big trucks and sport-utilities, but in this instance we're dealing not only with tight quarters in a jam-packed parking lot filled with tourist vehicles but the largest of all SUVs: Chevrolet's enormous Suburban in three-quarter-ton 2500 series that stretches 18 feet long and spreads more than six feet wide across the beam.
Just to turn this land ship usually involves advanced planning and plenty of linear feet in pavement, although the Suburban we're guiding through the Manitou lot happens to carry a secret steering weapon called Quadrasteer.
It's a sophisticated electronic steering system that not only turns the front wheels but rear ones too.
What's the advantage of steering with all four wheels?
It enables the huge wagon to maneuver at slow speed with amazingly tight turns that match the nimble movements of a small car, while at highway pace the system produces more straight-line stability and vehicle control regardless of the on-board load.
The new four-wheel steering (4WS) mechanism -- Delphi Automotive's Quadrasteer -- electronically controls the direction of rear wheels so all four wheels work together more efficiently than when only the front ones turn.
At speeds below 45 mph, rear wheels swing slightly in opposite direction to the front wheels, as governed by the smart electronic controller. The slower the speed, the more movement comes from the rear wheels.
This action of changing the direction of rear wheels at a slow speed actually abbreviates the size of the turning circle for Suburban.
With 4WS the diameter of the circle on a two-wheel-drive (2WD) model drops from 44.5 feet to 35.2 feet or fractionally less for a four-wheel-drive (4WD) Suburban.
Such pared distances virtually match the turning circle of an itsy-bitsy subcompact car.
And it means we're able to make a right-hand corner turn to slip effortlessly into our narrow parking space.
At speeds above 40-to-45 mph, Quadrasteer turns the rear wheels slightly in the same direction as the front wheels. This action reduces yaw or rotational motion in the conflict between front and rear wheels -- the tail wagging the dog, so to speak.
You notice the extra control most when changing lanes because big Suburban seems to zip quickly into the next lane with little wiggle from the rear end, but it remains quite stable when steered in a straight line with no detectable lateral motion at the tail.
Suburban 2500 packs a husky V8 powertrain, which makes it ideally suited for towing a heavy trailer load.
When you also rig it with Quadrasteer, something magical happens: The 4WD system in effect adds a new pivot point at the front of the trailer when maneuvering in traffic or turning corners.
It can take a hard right turn at an intersection with that trailer stretching behind and following obediently in an easy arching turn.
For trailer towing or just moving the wagon around town in tight confines, Quadrasteer becomes an easy-to-demonstrate advantage to the driver.
And the high-tech system is now optional for any version of the Suburban 2500 series 2WD or 4WD wagon. In fact, Suburban becomes the first full-size SUV to offer such revolutionary steering and handling control.
Current Suburban variations trace to designs in new format that emerged with model-year 2000 based on the full-size truck chassis of Chevrolet's Silverado pickup.
The structure utilizes an innovative three-piece modular frame with hydroformed front and rear frame sections that increase strength and rigidity, aid the assembly process by eliminating hundreds of weld points, and reduce squeaks and frame vibrations due to the good fit with suspension elements.
A boxy package provides the largest passenger cabin among all sport-utility wagons with room inside for eight or nine passengers.
Seating consists of a bench or twin buckets mounted on the front row and followed by a choice of second-row bench or buckets plus a third-row bench in sections that fold and flip forward to make more room for cargo.
Instruments include analog gauges with speedometer and tachometer, and a screen display of messages for engine management. Numerous storage spaces show up around the cabin, along with as many as five 12-volt power outlets.
Also, Suburban offers deluxe appointments with optional leather seating, rear air conditioning, a 12-disc CD changer, and a secondary fuel tank to extend the cruise range.
Power to motivate Suburban 2500 stems from two of the General Motors Vortec V8 engines linking to automatic four-speed transmissions.
The Vortec 6000 6.0-liter V8 serves as standard plant and produces more power and torque than any other standard engine in this class. Output rises to 320 hp at 4000 rpm, with torque skewed to 360 lb-ft at 4000 rpm.
It couples to the GM Hydra-Matic 4L80-E four-speed automatic transmission.
A Vortec 8100 8.1-liter big-block V8 is optional for a class-capping rating of 340 hp at 4200 rpm plus 455 lb-ft of torque at 3200 rpm.
Suburban in the 4WD edition has a dash-mounted switch to jockey between full-time all-wheel-drive (AWD) traction, rear-wheel or four-wheel high and low settings.
The StabiliTrak vehicle control system is an optional tool now for safety, as are power-motivated adjustable brake and accelerator pedals with memory settings.
New entertainment systems are also available for Suburban. Gear extends from customized Bose sound systems to rear-seat entertainment equipment with DVD player wired to a flip-down video screen and the subscription-based XM satellite radio service with superior sound quality and coast-to-coast reception through a hundred digital channels.
price points for Suburban 2500 begin at $38,650 for LS trim in 2WD. The Quadrasteer 4WS system lists for $4,495 on any 2500 version, with the DVD entertainment kit set at $1,295 and optional side-impact air bags are $350.
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| Vehicle Specifications: |
| 2003 CHEVROLET SUBURBAN 2500 4WS Specs |
| Description: |
Super-size sport-utility wagon
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| Model Options: |
Super-size sport-utility wagon
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| Wheelbase: |
130.0 inches
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| Overall Length: |
219.3 inches
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| Engine Size: |
OHV 6.0-L V8
OHV 8.1-L V8
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| Transmission: |
6.0-L:Auto/4 Hydra-Matic 4L80-E
8.1-L:Auto/4 Hydra-Matic 4L85-E
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| Drive: |
RWD
4WD Autotrac
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| Braking: |
Power 4-disc
ABS/DRP
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| Airbags: |
2 (front) + opt. 2 (side) |
| Gross Weight: |
2WD: 8600 pounds
4WD: 8600 pounds |
| Towing Capacity: |
2WD: 12000 pounds, 4WD: 12000 pounds |
| Price: |
2500 LS 2WD 2WS: $ 38,650
2500 LS 2WD 4WS: $ 43,145
2500 LS 4WD 2WS: $ 41,550
2500 LS 4WD 4WS: $ 46,045 |
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