We heard what sounded like a rifle shot reverberate off the rocky terrain of the Swamp Lake Trail and the tall timber that overshadows it. Turns out it was the exploding CV joint on the right front axle of the H3 Hummer pickup ahead of us. "Sounds like the mule just broke a leg," my seatmate says with a wry grin and a touch of an engineer's dry humor.

Too much throttle, rear tires off the ground wedged between a boulder and a log, and a fully extended front suspension brought about the sudden catastrophic parts failure under the front of the white Hummer H3T that now blocks our only path back to civilization. But it's not unexpected or a concern. In fact, such parts failures are exactly what the Hummer engineers want to see.

"This is why we take our 'development mules' on these off-road drives," says Gary Williams, H3/H3T program engineering manager. "We push them hard and when something breaks or malfunctions, it's just a normal part of our overall development process. We are here to make sure the Hummers are more than ready to handle what their future owners dish out." Williams is one of six Hummer engineers on this two-day adventure over the rugged 13-mile-long Swamp Lake OHV Trail near the town of Shaver Lake, California.

"We'll do a thorough inspection of the broken CV joint and analyze the situation in which it occurred when we get these trucks back to our development center in Warren [Michigan]. If it's determined there's a problem with the parts, we still have time to address it before the H3T goes into production."

HIDDEN GEMS
The H3T development mules Williams refers to are two heavily camouflaged white Hummer H3 pickups being tested-one is a 5.3-liter V-8 with an automatic, the other a 3.5-liter I-5 manual. Both have black bras over the front ends and matching covers that extend from the top of the four-door cab back to the rear and down to the lower body panels, completely covering the back half of the truck.

But we know what lies beneath the rear camo: a real pickup bed. Codenamed GMT745, the new four-door pickup is based on the existing H3, but with the chassis lengthened 23 inches to accommodate a five-foot Colorado/Canyon bed and full-size rear doors.

When we'd met up with Williams and the Hummer H3 pickup engineering development team in Fresno, 50 miles west of where we now stand watching the repairs get underway, we were told the bed is designed for full functionality.





The production H3T will come with the same tiedown system and bedliner style as found in the new full-size GM pickups, and for those who like to carry ATVs and other loads, the bed measures 48 inches between the wheelwells. It also has top-access bedrail cargo bins on each side for added storage and a bed extender to accommodate longer cargo needs. The trucks we're driving are equipped with the Adventure option package, which includes 33-inch Bridgestone Dueler A/Ts and an electric-locking front differential-both of which are invaluable on this trail.

As Daryl Ehrlich, H3/H3T powertrain development engineer, muscles a race-style Craftsman floorjack between the broken-down mule and the boulders underneath, John Chapman, the head wrench who is also a technician at GM's Desert Proving Grounds in Arizona, pulls out an electric impact wrench.

I look at my watch. Less than 20 minutes have gone by since the CV joint disintegrated. The tire's already back on the hub, Chapman is wiping axle grease from his hands, and we're ready to get moving again.

H3T LIFE CYCLE
Dominic Rimmer, the H3T vehicle performance integration manager, climbs into the seat next to me. He's come from Brazil, where he usually splits his time between production and engineering for the H3Ts built for markets outside of North America. (H3s for foreign markets are built in South Africa; foreign-market H3Ts will be built alongside the Colorado/Canyon in Brazil.) As we slowly make our way along the remaining mile of trail, he explains the basic evolution of the H3T.

In the first phase, the idea is brought to life virtually-using powerful computer-aided drawing programs-and physically as a one-off, "Proof of Concept" vehicle handbuilt by the team in GM's Experimental Engineering facility at Milford Proving Grounds. The resulting 134-inch-wheelbase concept pickup looked good despite welded-on door extensions and mix-and-match parts from other vehicles.

But sophisticated computer simulations and early development drives of the hand-built Proof of Concept truck revealed the longer-wheelbase H3T needed a number of upgrades and changes.

Rimmer says after those initial changes were made and the team had a definite direction for the truck, they handbuilt two-dozen mules in Warren, Michigan, to use as rolling design and engineering test platforms. These mules are put through a seemingly unending series of tests at GM proving grounds around the country, in real-world driving conditions, and in extreme environments from Death Valley to the Swamp Lake Trail.

Such a development process is what brought about the reinforced drop-frame on the new H3T; larger-diameter front and rear anti-roll bars; recalibrated shock tuning; V-8 steering pump on the five-cylinder model; a quick-steering rack and pinion for I-5 and V-8 models; higher-capacity cooling system; and standard 32-inch tires on new 16-inch steel wheels, plus the option of 33s and an electric locker.



FINE-TUNING OVER TIME
Over beers, fresh trout, and baked potatoes at our overnight camp along the edge of Shaver Lake, Todd Hubbard, who oversees H3/H3T ride and handling, says an extraordinary amount of seat time was devoted to making the new Hummer pickup handle well on and off-road.

Hubbard says they spent hundreds of hours tuning the suspension so the pickup's 55/45 front/rear weight distribution was well managed on road and off, on paved or gravel surfaces, whether towing or unburdened.

What remains in the H3T's development cycle is putting 45 to 50 integration vehicles-those actually built on a production line in Brazil-on the road where GM drivers will put more than 500,000 miles under their wheels. Many of these will be sacrificed in crash tests. The others will be crushed or used as parts donors for the next-generation Hummer.

Before actual production begins in mid-2008, another 100 or so preproduction H3T models will be built. Eventually these, too, will be recycled or crushed.

It saddens me to turn the switch from 4L to 2H. Two days behind the wheel of this new Hummer pickup has shown me just how good a vehicle this is. It's ideal for those who want that Hummer look without sacrificing anything in utility value and performance.

I make one last attempt at saving one of these mules from its predestined fate of destruction. "Honest, I'll keep it in a car hauler trailer and use it only off-road," I mock a hands-clasped plea to Williams as I exit the V-8-powered white H3T. He smiles. "Nice try."

While the camoed H3Ts were testing on the mountain trails, we also got access to some non-camoed H3Ts as they were being photographed for their big debut at the 2008 Chicago Auto Show in February. The longer wheelbase and modified frame will make this essentially a midsize pickup, with much more versatility than the H2 SUT. GM's bedrail system will come standard, and Hummer dealerships will have a huge selection of factory parts available right at the dealership. The 2009 models won't hit dealerships until the last half of 2008.

Among some of the bed accessories offered by Hummer dealerships will be bike and motorcycle tiedown cleats, storage toolboxes, and sliding gear walls. Integrated into the plastic inner bed wall of the H3T are four side-mounted storage cubbies, two on each side. They're not huge, but they'll hold some tools, gloves, and tow straps. There's also a "work truck" bed frame for carrying ladders and long pipes.





2009 HUMMER H3T PRELIMINARY SPECS
GENERAL
Location of final assembly Shreveport, Louisiana
Body style Four-door, five passenger crew cab pickup
EPA size class Compact pickup
Drivetrain layout Front engine, 4WD
POWERTRAIN
Base engine I-5, alum block/head
Bore x stroke, in 3.76 x 4.00
Displacement, ci/L 223/3.7
Compression ratio 10.0:1
Valve gear DOHC, 4 valves/cyl, VVT
Fuel induction Multipoint sequential fuel injection
SAE horsepower, hp @ rpm 242 @ 5600*
SAE torque, lb-ft @ rpm 242 @ 4600*
Opt engine 90° V-8, alum block/heads
Bore x stroke, in 3.78 x 3.62
Displacement, ci/L 325/5.3
Compression ratio 9.9:1
Valve gear OHV, 2 valves/cyl
Fuel induction Sequential fuel injection
SAE horsepower, hp @ rpm 300 @ 5200*
SAE torque, lb-ft @ rpm 320 @ 4000*
Base transmission MA5 5-speed manual
1st 3.75:1
2nd 2.20:1
3rd 1.37:1
4th 1.00:1
5th 0.73:1
Reverse 3.67:1
Opt transmission Hydra-Matic 4L60 4-speed automatic
1st 3.06:1
2nd 1.63:1
3rd 1.00:1
4th 0.70:1
Reverse 2.29:1
Axle ratio 4.56:1 (I-5), 4.10:1 (V-8)
Final drive ratio 3.33:1 (I-5), 2.87:1 (V-8)
Low range ratio 2.64:1 (std), 4.03:1 (opt)
Crawl ratio (1st x axle gears x low) 45.1:1, 68.9:1 (I-5); 33.1:1, 50.6:1 (V-8)
Recommended fuel Regular unleaded
CHASSIS
Construction Welded steel frame, electro-galvanized steel
Suspension, front/rear Independent SLA torsion bar, stabilizer bar/Hotchkiss multileaf, semi-elliptical dual-stage leaf spring, stabilizer bar
Steering type Power-assisted rack-and-pinion
Brakes, front/rear 12.4-in disc/12.3-in disc; 4WABS
Wheels 16x7.5-in steel (alum opt)
Tires P265/75R16 (std), LT285/75R16 Bridgestone (opt)
DIMENSIONS/CAPACITIES
Wheelbase, in 134
Length, in 211.9
Width, in 85.5
Height, in 72.2
Track, f/r, in 65.0/65.5
Ground clearance, in 9.1
Approach/departure angle, deg 37.5/28.0
Grade capability, % 60
Side slope capability, % 40
Water fording capability, in 24.0 (at 5.0 mph)
Headroom, f/r, in 40.6/39.9
Legroom, f/r, in 41.9/33.8
Shoulder room, f/r, in 54.4/53.7
Cargo box volume, cu ft 35.7
Cargo box LxWxH, in 59.3x60.1x19.4
Width bet wheelhousings, in 44.2
Max GVWR, lb 6100 (V-8)
Maximum towing capacity, lb 5900 (V-8 est)
Fuel capacity, gal 26
*pending SAE certification

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