Despite their associated cost and hassles, the Environmental Protection Agency’s 2007 emissions regulations will, one day, be considered a boon to the trucking industry because they ushered in a host of new heavy-duty truck models that might have otherwise remained mere engineering drawings, at least for a few more years.
The Kenworth T660, introduced in 2006 to replace the renowned but aging T600, is one such model.
Truck builders are usually reluctant to make significant changes to their lineup unless customers demand them or sales start to slide. The EPA regs, however, forced accelerated design modifications, largely because existing vehicles were unable to neatly accommodate the bigger cooling systems necessary for new emissions-compliant diesel engines. Manufacturers took this opportunity to develop advanced models that met the mechanical requirements but also offered owners greater value and drivers more comfort.
This doesn’t mean, though, the T660 is a new truck. It’s not. Instead, it is an enhanced –– or “evolutionary,” in the words of company officials –– version of its predecessor, which was a truly futuristic Class 8 vehicle when unveiled in 1985 and probably the most popular Kenworth ever made, at least among fleet buyers.
The T660 capitalizes on the basic shape of, and periodic improvements to, the T600. Its defining features are a newly designed hood, grille, headlamps, bumper and side skirts. Together, these form a slightly smoother aero design that’s said to reduce frontal wind resistance by one percent. The unit also sports better forward lighting, upgraded multiplexed electrical instrumentation, proprietary seating and more.
To experience this revised classic first-hand, I traveled to Renton, Wash. recently and visited Kenworth’s research and development center, a sort of holding pen for test trucks past, present and future.
In the interest of full disclosure, I should mention that I’m partial to the T600, having logged many miles in an early 1990s version, pulling a reefer between the Midwest and East Coast. Sitting in the T660 for the first time, I was immediately reminded of my former life as a cheese hauler. The cab’s interior dimensions, the view through the windshield, the feel of the doors –– nearly everything around me –– evoked memories of the “T6” that had been my home on the road for several years.
At the same time, of course, this truck was vastly different, outfitted with all of the latest components and refinements, from a 13-speed Eaton UltraShift transmission and 500-HP Cummins ISX engine to KW’s anti-idling Clean Power technology to the 72-in. sleeper, high-end Diamond VIT trim package and high-tech driver information display with GPS. In the words of a formerly popular automotive ad, “This wasn’t your father’s Kenworth.” Such vehicular opulence would, no doubt, quickly spoil even the crustiest veteran drivers.
I found the T660’s freshly minted front end to be equally impressive. The grille, five percent larger and about one-in. taller than that of the T600, is decorated with a bolder, brighter chrome crown. The two-piece, beautifully sculpted bumper is made from Metton, a lightweight and extremely rugged composite material. The hood, constructed of sheet molding compound (fiberglass on steroids), is about 2 in. longer and flanked with smoothly rounded fenders designed to quell turbulence at highway speed. Its trailing lines are continued along both sides of the truck, represented in artful, flowing side skirts and steps that provide both form and function to a truck whose history was built on cutting edge aerodynamics.
My test unit was hitched to a fully loaded 53-ft. dry van, and the combination weighed near the legal limit. Clearing the guard shack at the R&D center, I wound my way toward I-5, trying hard to avoid sideswiping any of the closely parked cars along the streets and, at the same time, trying to gauge the low-end performance of the Cummins-Eaton powertrain.
Within the first few blocks of my trip, I’d already switched the UltraShift from automatic to manual mode because I was dissatisfied with the high engine speeds at which it was shifting. I later learned that shift points are a programmable feature of this transmission. That’s a good deal, but in my humble opinion, low-rev shifts should be the default setting, at least in the first four or five gears. Fortunately for me, the tranny does compensate for driver ignorance. Several times during my trip I rolled to a stop without downshifting from high range. The UltraShift’s computer immediately went into the auto mode and chose second gear when I attempted to start moving again.
Driving the T660 is a pleasant experience, nearly identical to driving a T600B, probably because both vehicles use the same cab. There isn’t much difference in the comfortable ride either. The suspension –– long taperleaf front and four-bag AG380 rear –– is unchanged in the latest model. The newer truck, however, might be slightly quieter, thanks to the mandatory diesel particulate filter, an expensive emissions device that both removes soot from the exhaust stream and seems to serve as a secondary muffler. The test rig sported Kenworth’s optional QuietCab package so its interior sounds were even more hushed.
I cruised south on I-5 and pulled into a truck stop at Exit 99. There, I briefly checked out the T660’s Clean Power unit. This is a revolutionary system that’s available as a factory installed option in T660s fitted with 72-in. AeroCab sleepers. According to the company, Clean Power “uses dedicated, advanced deep-cycle batteries that power a thermal storage cooler with 21,000 BTUs of cooling capacity. Once the truck is shut off, a thermostat regulates the desired temperature and a variable speed fan circulates chilled air through a duct located near the bunk.” The unit will reportedly keep the sleeper cool even when the ambient outside temperature is 95 degrees, and it “will provide accessory power for up to 10 hours.” With fuel prices apparently locked above $3 per gal., Clean Power seems like an option that would quickly pay for itself.
Departing the truck stop after my lunch break and self-guided walk-around inspection, I headed for U.S. Highway 101, then picked up state route 8 going toward Elma. Before reaching that fine town, though, I found a wide spot in the road, turned around –– “did a flip,” in the vernacular of the trade –– and retraced my tracks back to Kenworth’s R&D center, hoping to slide through Seattle’s notoriously thick traffic before the afternoon rush hour began. The entire trip lasted just five hours and stretched across 147 miles.
Consistency is the central element of this truck. Since the latter 1980s, Kenworth has profited handsomely from the popularity of the T600, as more and more truckers began to understand the relationship between vehicle shape and fuel economy. That truck, updated to stay current with technology and driver comfort features, continued to sell well until it went out of production last year. Now the company hopes hang on the T660, which is even more refined than, yet much the same as, its predecessor. If this new model lives up to those aspirations, I’ll be reviewing the T670 (or perhaps the T660.1) in about 20 years.
KENWORTH T660 SPECS
Tractor – Kenworth T660
Wheelbase – 226 in.
Engine – 2007 Cummins ISX-500, 500 HP@2,000 RPM, 1,650 lbs.-ft.@1,200 RPM
Clutch – Computer operated. No Clutch Pedal
Transmission – Eaton 13-speed UltraShift LHP (RTLO-16913L-DM3)
Drive Axles –Dana DSP40 40,000 lbs.
Axle Ratio – 3.55 to 1
Rear Suspension – AG380 38,000 lbs. 52-in. spread
Front Axle – Dana Spicer E-1202I 12,000 lbs.
Front Suspension – Taperleaf 12,000 lbs. with shock absorbers
Steering – TRW TAS65
Foundation Brakes:
—Front – Air Disc Brakes
—Rear – Bendix ES S-Cam 16.5 x 7 Dual
Wheels – Stylized II Aluminum 22.5 x 8.25 /Dura-Bright buffed
Tires
—Front – Bridgestone R287 295/75R22.5
—Rear – Bridgestone M720FE 295/75R22.5
Fifth Wheel – Jost Air Slide JSK37UWL
Fuel Tanks – Dual 24.5-in. 120 gal. aluminum
Cab Interior Trim – Diamond VIT
Seats – Air Cushion Premium Plus high-back with fold-away armrests
Sleeper – 72-in. AeroCab with Diamond VIT
Additional Equipment: Clean Power system; dual high intensity discharge (HID) headlamps; GPS Navigation system; QuietCab package; 2 PACCAR 2000-cca batteries; Leece-Neville 185-amp alternator; PACCAR 105P 12-volt starter; Bendix 6S/6M with automatic traction control and electronic stability program; silicone coolant hoses; low voltage disconnect; Bendix AD-IS air dryer; Intebrake.
Cab features: AM/FM/CD radio with Sirius module; electric door locks w/remote keyless entry; DayLite doors; 18-in. 4-spoke leather steering wheel; adjustable steering column with telescoping tilt.
