New GM chassis cab: Wait til next year

WITH a wink and a nod, General Motors told those attending The Work Truck Show that details of the company's new full-size truck are being closely guarded and are not to be released.

But if you want to know what it will look like, you can get a good idea by checking out the new Yukon already on dealer showrooms.

The general public will not receive details on the new pickups until close to its debut as a 2007 model this fall. However, the commercial truck industry will be able to slap tape measures on the chassis cab during a series of measuring sessions that are being planned — one for August or early September, another in November. A session for the half-ton pickup has already been conducted.

Attendance will be limited to two representatives per company, and those attending will be required to sign confidentiality agreements. Full-size trucks will be at the summer/fall session, but there are no guarantees that GM will have the chassis cab available for scrutiny until the November event.

At first glance, this fall's measuring sessions may not provide much lead time. But GM plans to roll out the new models in stages — and the chassis cab will be the last iteration to be introduced.

Here's the roll-out schedule:

  • The company will start the 2007 model year with the current generation truck that GM will call the “Classic.”

  • As the model year unfolds, the company will roll out the new models by manufacturing plant. The light duty crew cabs will be the first model — expected in the fourth quarter.

  • Regular extended cabs will be added later in the fourth quarter.

  • Heavy-duty models will start in the first quarter of 2007. The chassis cab will be last. The roll-out is expected to take until 2008.

More heat? No sweat

Tighter diesel emission regulations that will take effect in 2007 may slash exhaust soot and raise exhaust temperatures, but they won't appreciably affect truck body and equipment installations on GM and Isuzu trucks, according to GM's Steve Matsil and Isuzu's Dan Cutler.

“We have over 60,000 of these vehicles operating today,” said Cutler, executive director of product development for Isuzu commercial trucks. “And about 90-95% of your body applications will mount on the 2007 N/W product (N Series Isuzu and W Series GM trucks) without any hiccups. For the other 5%, we have engineers out visiting body shops. We will have some alternatives.”

Matsil said a lot of what GM will be using on its 2007 trucks is proven technology that has seen several years of service on Isuzu trucks in Japan.

“We feel pretty good that we have proven field experience,” Matsil said. He added that engine cooling systems have not needed to be modified substantially in order to keep engine temperatures within desired operating range.

Matsil, however, said that packaging of equipment for specialized applications such as sweepers, airport ground support equipment, and municipal refuse trucks will need special consideration.

Real estate developments

Matsil showed illustrations of current-model and 2007-model engines for a variety of GM models. He pointed out that the new hardware will have very little impact on the “real estate” of the vehicle — the space where body and equipment installations might occupy.

Distributors, however, will need to watch their incomplete vehicle manual to see if GM will allow the use of U-bolts in certain areas of the frame rails. In instances where U-bolts are not allowed, shear plates must be used instead.

GM will insulate the exhaust system with dual wall insulated pipes to accommodate the higher temperatures that the new exhaust systems will generate.

“Pipe and component skin temperatures will not be much higher than they have been,” Matsil said.

The big difference is in the exhaust gas, and we are at work on a cooler that will lower the temperature of the exhaust gases.”

Why it's hot

The spike in exhaust temperatures are the result of having to clean the diesel particulate trap.

“The regeneration is an event that you would like to have happen as infrequently as possible. We suspect that most of these regenerations will be transparent to the operators.”

The particulate filter consists of a series of closed-end channels. This causes the larger soot particles to be trapped as the gas passes through these permeable walls. When the walls are covered with soot, the filter must be cleaned.

GM monitors the need to clean the filter by comparing the difference in incoming and exiting exhaust gas pressures. When the difference reaches a prescribed level, it is time for “the furnace” to come on and incinerate the soot.

All of these functions — including engine operation and the exhaust monitoring — are electronically controlled. GM is doubling the lines of computer code in order to operate the new exhaust systems. “This is a significant intellectual property investment,” Matsil said.

GM anticipates that normal regeneration of the particulate filters will postpone any service of the filters until after the truck has 100,000 miles of service. Depending on the brand of truck, the filter will need to be vacuumed out — either by placing it on a piece of shop equipment designed for this purpose or by cleaning it with the filter remaining on the truck.

So what's new now?

Because of the new truck that GM has on the way, current and early 2007 models will be carryover. But:

  • In an effort to reduce delivery times, many special equipment options (SEOs) are becoming regular production options (RPOs), according to GM's Mike Eaves. He suggested checking the GM Web site for details.

  • The manual transmission will be canceled on C4 and C5 models.

  • The lightest-rated front axle also will be cancelled, making the 7,000-lb axle the base axle for C4 models.

  • The base suspension of C4 and C5 models will become riveted. Bolted suspensions will be available as options should the body application require that the suspension be relocated.

  • A 35-gallon fuel tank will be offered on 4×4 models. It will be mounted under the driver's door. Ground clearance limitations will prevent this option from being available on 4×2 models.

  • Fuel tank taps are being made optional. Those who would like to fuel auxiliary equipment from the truck's fuel tank must order the tank with an auxiliary fuel port.

  • Allison transmissions will be changing for the 2007 model year. The six-speed 1000 MH and the 2200 MH will be available in the place of the corresponding five speed automatics.

The 2007 model year starts June 26. However, the exact introduction date of some interim models has not yet been determined.

“We will phase in some exhaust system content,” Eaves said. The vertical exhaust for the C6 dump truck is one example. The horizontal exhaust will be limited to wheelbases greater than 140 inches.

The higher exhaust ratings of the Caterpillar engines also will be phased in.

Dan Cutler gave this update on the Isuzu product line:

Isuzu typically changes its model year in January. For the remainder of the 2006 calendar year, the 12,000-lb GVW Class 3 N and W series will remain 2006 models.

All the specifications are carryover for 2006, including the gasoline engine — which may be an option for medium-duty truck customers who are not ready to try the 2007-model diesel engines, Cutler said. He later added, however, that the automatic transmissions that are used with the gasoline engines do not come with PTO openings. Hydraulic power must be generated with clutch pumps.

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