Engineered elements of the '07 Sport Trac: while Honda is getting props for the Ridgeline, there's another four-door out there with a composite bed to boot.

The second-generation Ford Sport Trac, an '07 model, has hit the streets, so we talked with Craig Brewer, chief engineer, to get some insights on the vehicle ...

* Compared with a conventional four-door Explorer, 80% of the body parts are different. Forward of the B-pillar, the panels are the same, including the aluminum hood.

* The independent front and rear suspension (front: short- and long-arm design with coil-over shocks and a 32-mm stabilizer bar; rear: trailing blade short- and long-arm design with coil-over shocks and 23-mm stabilizer bar) are the same as on the four-door. But given that the Sport Trac has a bed, the tuning is different.

* The frame for the Explorer is constructed in three sections: front, middle, rear. The mid section of the Sport Trac is 16.8-in. longer than the four-door model. There is an additional cross member on the Sport Trac for lateral stiffness. (The Explorer frame picked up on an engineering design feature used for the Ford F-150 pickup, with the cross beams passing through the longitudinal frame rails. This is called "tube-through-tube.")

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* Compared with the first-generation Sport Trac's frame, the new one offers 444% more torsional stiffness. This is primarily achieved by having gone from a C-channel design for the frame elements to one that's fully boxed.

* The Explorer is the first Ford application of a six-speed transmission in a rear-wheel-drive application; the six-speed is mated to a 4.6-liter, 24-valve V8. This transmission is the outcome of work that was done as a joint venture with ZF. The ZF-manufactured six-speed was first offered in a Ford product in the '05 Lincoln Navigator. The one used in the Explorer is similar. It, however, is build at the Ford Livonia Transmission Plant. (There is also a 4-liter V6 and five-speed automatic combo available.)

* Like the previous generation, the Sport Trac has an SMC composite box--inside and out--with the outer being painted body color and the inner a molded-in black liner. The bed consists of four panels: floor, headboard, and sides. There are three storage bins molded into the panels, one behind the headboard and two behind each wheel well. The tailgate, however, is steel. The D-pillar for the tailgate is a hydroformed, U-shaped steel beam. The hydroforming not only allows the assembly to have an overall reduced part count (8 vs. 15 for the previous design), but it also cuts 7 lb. The bed underwent testing similar to that used for the bed of an F 150, including a 55-gallon drum drop test, in which a drum is dropped onto the bed as though someone got it up onto the tailgate and then ... Oops! The box offers 37.5-[ft.sup.3] of cargo capacity and can handle a 1,380-lb. load (in a 4x2 V8 configuration).

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* The vehicles benchmarked during the development of the truck include: Honda Ridgeline, Toyota Tacoma, Dodge Dakota, Nissan Frontier, and the four-door Explorer (Brewer has worked on Explorers for nine years, so that's not surprising).

By Gary S. Vasilash, Editor-In-Chief