|The New Chevy-GMC Heavyduty
By Jamie Von Druska
General Motors is on a mission. Finding themselves on the shorter end of the pickup truck market stick, they are determined to not only rebuild their entire truck lineup, but build the best trucks on the market period. That's a tall order these days in this highly competitive market, but from what we have seen and driven so far, you would be foolish not to take them seriously.
For those that may have not have been keeping score, GM started its rebuilding process in 1999 with the launch of the new half and three-quarter ton pickups. In 2000 GM introduced all new full-size sport utilities and for 2001 the new heavy-duty full-size pickups round out the offerings. GM plans to sell more than 250,000 heavy duty units in the 2001 model year and has spent an enormous amount of time going back to the customer base in search of the right changes and improvements. Customers demanded great driver and passenger environment, affordability, a well-built, safe and secure vehicle and most importantly a "a truck that looks like a truck". GM then set out to create class leading powertrains, payload capacity, towing and hauling.
GM now leads the entire class (at least this month) with the most powerful gasoline and diesel engines available. All new powertrains are validated for an operating life of at least 200,000 miles without major component failures. At the same time improving maintenance issues and improved economy over their predecessors.
Duramax 6600 V8
GM's new Duramax 6600 replaces previous the 6.5 liter turbo diesel. Developed jointly with Isuzu Motors, this new powerhouse is a 90-degree, injection, overhead valve, four valve-per-cylinder turbocharged V8, with aluminum high-swirl cylinder heads and puts 300hp and 520 lb./ft of torque at 1800 rpm to the crank. This puts the Duramax more than 65hp and 20 lb./ft above Ford's 7.3l and more than 70hp and 70 lb./ft above the Dodge 5.9l diesel. What this newfound power translates into is class leading pulling and hauling capability while still achieving 19 percent better fuel economy over the outgoing 6.5 liter. GM lined up all the competition at the press introduction with 22,000lbs GCW trailers with wind resistance screens to simulate towing a very large motorhome. The first thing you noticed in the GMC and Chevy vehicles equipped with the new Duramax diesel were how much quieter they were than any of the competition (GM claims half as quiet as the Ford 7.3 liter). Through the towing and hauling exercises, the new GM models had noticeably more pep on steep grades while climbing hills than either the Ford or Dodge offerings. Plus the new Allison transmission with grade braking are a gem with this engine, but more on that later.
Vortec 8100 V8
Also new for 2001 is the Vortex 8100, nearly 80 percent brand new over the 7.4l big block. The new Vortex 8100 shares its predecessor Vortex 7400's valve and bore centers and bore diameter. But its stroke has been increased by 9.4mm for a higher displacement and more power. With 340hp and 455 lb./ft of torque at 3200, this new motor even edges out the power outputs of Ford and Dodge's V10 models (275hp and 300hp respectively).
Even with this increased performance, mileage has improved 4 percent over the 6.5 liter V8. The low maintenance design only requires oil and filter changes during the first 100,000 miles, and coolant changes every 150,000 miles.
On the street this new big block V8 has impressive power, easily moving a full horse livery trailer over the hills of Branson Missouri. Power delivery is smooth and quiet with more than 90 percent of available torque at 1800 RPM. This new motor really moves off the line and won't leave you wishing for more power when the need arises
The Vortex 6600 replaces the previous 5700. With 300hp and 360 lb./ft of torque, the 6600 is the most powerful standard engine available in its class with Ford trailing at 260hp and Dodge at 250hp. The 2001 Vortex 6600 features cast-aluminum cylinders, shaving 55 lb. of weight in the process thus providing more valve seat durability over the 5700 it replaces. Volumetric efficiency has been improved with new exhaust ports borrowed from the Corvette, while dual catalytic converters and exhaust pipes minimize back-pressure and provide more power. What all this translates into is significantly more power in the standard GM heavy-duty offering with improved fuel economy and even better reliability.
To compliment the new engine lineup, GM has two all new units added to it's existing transmission offerings for 2001.
First out of the block is the new smooth shifting, German made ZF S6-650. This slick new six-speed manual transmission is the first of its kind in this segment to be offered in both gasoline and diesel powered vehicles. First gear is designed as a 'creeper gear' for better low-end performance and towing. With reverse and first gear in the same shift gate, users can throw the gear lever forward for reverse and straight back for first, which should make snowplowing and low speed maneuvers a bit easier. Sixth gear is positioned away from the seating area, giving more room to both driver and passenger during extended highway cruising. This transmission is also equipped with a PTO provision providing up to 25hp capacity.
Next up is the new Allison M74 1000 five-speed automatic. Allison is a leading supplier of automatic transmissions for large application commercial truck and bus markets. Taking those years of experience, they have supplied GM with a great unit full of wonderful features.
The Allison 1000 has full electronic control of shift timing. With fuzzy logic programmed into its controls, the transmission provides a major new benefit GM calls Engine Grade Braking®. If a driver descends a hill, the Transmission Control Module (TCM) senses the weight of the load, the vehicle's speed and the deceleration rate and automatically downshifts to a lower gear to help slow the truck. In GM's proprietary Tow-Haul mode via a push button on the transmission stalk, the Allison transmission will do multiple downshifts from fifth to fourth and from fourth to third, using steadily lower gears to help slow the decent. Tow-Haul mode also minimizes the amount of "shift-business" as GM calls it while navigating large hills or under heavy towing conditions. All this fuzzy logic actually works rather well in application, forcing the transmission to downshift one gear just about the time we were going to put a foot on the brakes to slow us down. Kind of creepy actually, as it seemed to sense whenever we were about to brake downhill, firing off another downshift. If you do any towing or heavy hauling, this is one transmission you don't want to be without.
Frame, Suspension and Braking
GM used hydroforming technology (again borrowed from the Corvette) in the front frame rails of all models, increasing strength and stiffness. In addition, the 3500 Series are the only chassis cabs in their segment to meet all of the National Truck Equipment Association's requirements for quick, cost-effective mounting of specialized bodies and equipment. They have clear, flat 34-inch wide rails and a larger, standard 50-gallon dual fuel tank system.
A long and short-arm independent front torsion bar suspension is standard on all models. It provides a smoother ride, greater durability, more on-center feel and better stability over preceding models. Semi-elliptic multi-leaf rear springs do duty in the rear. Front and rear track have also been increased, giving yet more stability. On the road these new GM models were extremely quiet, kept body-roll in check and rode exceptionally well for their heavy-duty nature.
Four wheel discs featuring GM's Hydro-Boost brake assist system and four-wheel ABS are standard on all models. Audible brake pad wear sensors have also been added both front and rear.
Wheels and Tires
Wider standard 16 x 6.5 inch eight-bolt wheels are standard for 2001. Also higher E-load range tires help provide for increased load-capacity. 2500HD models feature 245/75R-16 radials with either all-season or on/off road design, depending on the model. The 3500 Series have standard 215/85R-16 highway or on/off road radials. Full size spare is standard.
Hauling and Trailer Capability
With all the new found power improvements, improved chassis rigidity and higher capacity brakes comes new payload capacities and increased towing and hauling capabilities The 3/4 ton comes in at 9,200 pound GVWR (400 lb. more than competitors) and payloads of up to 3,954 lb. The one ton pickup is rated at 11,400 pound GVWR (200lbs more than Ford and 900 lb. more than Dodge). Both the 8100 and Duramax Diesel V8 permit towing trailers weighing up to 12,000 lb. and provide a maximum 22,000 lb. gross combined weight rating (GCWR).
The Silverado HD (pictured above) and Sierra HD have a new massive front-end appearance that includes wider openings and bolder chrome accents. The hood is elevated and front bumper pads thicker to accommodate a two-inch higher body height. Integrated wheel flares add to a strong, aggressive appearance. Dooley models feature a new one-piece composite rear fender that reduces weight while adding durability. Cargo boxes have also been enlarged primarily between the wheel wells giving an additional 2 percent increase over previous models.
Regular, four-door, extended and Crew Cab sizes have all been increased over previous designs for significantly more interior room. The new Crew Cab has 1.1 inches of additional head room and an extra 1.4 inches more hip room up front. Rear seat passengers see an additional .7 inches more rear leg room, .2 inches more rear shoulder room and 3.6 inches more rear hip room.
The Crew Cab's rear seat is a 40/60 split bench with room for three passengers. The seat can be folded to create a large, flat surface that's ideal for carrying luggage, tools or pets. With bucket seats, the Crew Cab also has a center console with a large, lockable storage volume, two cupholders, extra storage in the lid and coin holder. The rear of the console, like that of the extended cab, also has two more cupholders, adjustable air conditioning vents and a small storage bin for rear passengers. Depending on trim level, an overhead mini or full feature console also provides additional storage room on all models.
In addition, GM has announced the OnStar System will be standard on uplevel Silverado LT and Sierra SLE extended cab and Crew Cab models. Dual airbags are also standard on all models with a passenger side deactivation switch on regular and extended cab models to protect small occupants.
The new Chevy Silverado and GMC Sierra each offer more than 32 heavy-duty models including 3/4 ton (2500 series) and one ton (3500 series) regular cabs, four-door extended cabs and chassis cabs, plus there are even special versions available with reduced gross vehicle weight for alternative fuel vehicles. With the extensive improvements made and the time taken to seriously listen to customers requests, GM has moved ahead in the heavy-duty segment. Superior engines, great transmission offerings and stellar performance in all categories make a compelling story. This is one truck definitely worth taking a serious look at.