by Harry Pegg
Times are changing for people who like to pull trailers. General Motors new ‘Quadrasteer’ four-wheel-steering system brings a whole new dimension to low-speed manoeuvrability and high-speed stability in full-size pickup trucks. Supplied to GM by Delphi Automotive Systems, the Quadrasteer 4WS system is now offered on the 2002 GMC Sierra Denali all-wheel-drive extended cab short box pickup.
After a couple of weeks with the truck, I’ve become an enthusiast. It’s manoeuvrability in 4WD mode is amazing. And the difference in stability when pulling a trailer is terrific.
Quadrasteer uses conventional front-wheel hydraulic power steering in combination with an electrically powered rear wheel steering system, to adjust rear-wheel angles, turning them opposite to the front wheels at lower speeds and in the same direction as the front wheels at higher speeds, for astounding manoeuvrability and control. At lower speeds, the system reduces curb-to-curb turning diameter by 21% to 37.4 ft., which is about the same as a compact car. Tight parking spot? No problem.
At highway speeds, Quadrasteer reduces yaw to improve stability, providing safer, more confident, lane changes, passing and evasive manoeuvres, especially in wet or windy conditions.
The increase in trailering control is equally amazing. With Quadrasteer, Sierra Denali and trailer move down the highway almost like a single unit. You can change lanes more quickly and safely with hardly any trailer sway even at 100 km/h with a 6,000-lb. trailer.
2002 GMC Sierra Denali Quadrasteer. Click image to enlarge
In the city, the truck can pull a trailer around a corner, without swinging wide to clear the curb. Trailer manoeuvring in tight spaces like a boat launch or campsite is exceptional, in fact I had to re-think a lot of things I’d been taught about backing a trailer. The thing responds much more quickly than with a conventional truck, meaning much smaller steering inputs are required.
Even when you’re not pulling a trailer, the 4WS system gives you the ability to corner like a car. It works so well, I found myself keeping 4WS turned on nearly all the time.
The Sierra Denali’s chassis has been given a number of enhancements, including a higher capacity rear axle and increased GVWR. A larger 9.75-inch rear ring gear is used to increase the rear axle’s gross weight rating by 250 lbs. (113.4 Kg) to 4000-lbs. (1814.1 Kg). Coupled with the extra capacity already available in the Sierra Denali’s 51-mm twin-piston calliper front and 45-mm twin-piston calliper rear brakes, the larger rear axle provides a higher 7200-lb. GVWR, 400 lb. (1814.1 Kg) more than before.
Payload, at 1722 lb. (781 Kg), is nearly the same as before despite a small increase in weight from the Quadrasteer system. GCWR has increased by 2,000 lb. (907 Kg); coupled with a new 4.10 axle ratio, it increases trailering capacity by 1300 lb. (589.6 Kg) to 10,000 lb. (4535.1 Kg).
The ZX3 ride control suspension provides driver-selectable shock damping for its 46-mm front and rear shocks. Using an instrument panel-mounted switch, the driver can select either smooth or firm ride.
Power is from a 6.0-L Vortec V8 connected to a four-speed automatic transmission with tow/haul mode selector, which delays upshifts when towing a trailer, reducing gear hunting on grades. Despite being hooked to a full-time all-wheel-drive system, the truck delivers decent fuel economy, even when pulling a medium-weight trailer.
The interior is pure luxury. Leather seating, power windows and locks, keyless entry system, power seats, heated seats, great stereo. This is a pleasant truck to pull with. Instrumentation includes a trip computer which gives, among other things, a 15-day history of the vehicle’s operation, fuel consumption, business trip odometer, private use trip odometer. You use this device to select operation of various systems like alarm feedbacks, door locks and the like.
The Denali’s long list of standard equipment includes: the Vortec 6000 SFI V8 engine, four-speed electronic automatic transmission with overdrive, Quadrasteer four-wheel steering, all-wheel drive, adjustable ride control electronic suspension, full-featured leather front bucket sets with dual 6-way power seat adjusters, driver side memory feature and power lumbar adjustment, heated front seats, HomeLink three-channel transmitter, 17-inch 6-spoke aluminum wheels, tubular side steps, fog lamps, heavy-duty trailering equipment, locking rear differential, colour-keyed tonneau cover, next generation reduced force driver and passenger airbags, all-wheel drive, four-wheel disc brakes with ABS, automatic headlamp control, OnStar communication system, driver message centre, lockout protection solar-ray tinted glass, deep-tinted rear glass, heated power outside mirrors, PASSLock security system, electrochromic inside rearview mirror with compass and temperature readout, air conditioning, power windows, power door locks with remote keyless entry, cruise control, rear window defogger, locking spare tire carrier, leather wrapped steering wheel, variable intermittent wipers, front tow hooks, tilt steering wheel with with radio controls, driver information centre (fuel economy, personal trip computer, business trip computer, 15-day vehicle history, programmable door locks, language selection, fuel remaining range and annual mileage), driver message centre (monitors 18 systems including transmission overheat, low fuel, low coolant, security, oil level, oil pressure and oil change interval), AM/FM audio system with 6-disc in-dash CD changer and cassette player, rear seat audio controls, and independently switched dual cargo-area lamps.
For more info on the Quadrasteer system, see Technical Editor Jim Kerr’s Auto Tech report.
Technical Data: 2002 GMC Denali
|Price as tested||$56,795|
|Type||full-size 4-door, extended cab pickup|
|Layout||longitudinal front engine, all-wheel-drive|
|Engine||6.0-L OHV V8|
|Horsepower||325 @ 5000 rpm|
|Torque||370 lb.-ft. @ 4000 rpm|
|Transmission||4-speed automatic w/Tow-Haul mode|
|Wheelbase||3645 mm (143.5 in.)|
|Length||5781 mm (227.6 in.)|
|Width||2120 mm (83.5 in.)|
|Height||1877 mm (73.9 in.)|
|Fuel consumption||City 18.9 l/100 km (15 mpg)|
|Hwy 14.3 L/100 km (20 mpg)|
|Warranty||3 yrs/60,000 km|