Ford Super Duty: it's all about capability.

Unlike the F-150, which has seemingly become more lifestyle accessory than workplace necessity, not too many of Ford's Super Duty trucks (F-250, F-350, F-450 and F-550) are bought for show. "It's all about capability," says Susan Dehne, chief nameplate engineer for F-Series Super Duty trucks. Which translates into bread-and-butter commercial concerns like usable torque, towing capacity and payload weights. So it's not surprising that when Ford re-designed its Super Duty trucks for 2005, it targeted being best in class in all of those areas. Though not a ground-up transformation like last year's F-150, the Super Duty line has been given significant strategic tweaks designed to make it a more capable working vehicle.

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TOWING AND PAYLOAD. Dehne says that 90% of Super Duty owners tow, so improving towing capacity and operation was a paramount concern for her development team. On the low-end of the range, the V8-powered truck increases its tow rating by 3,000 lb. to top out at 12,300 lb. V10- and diesel-powered versions see a 1,600-lb, increase for a maximum load of 15,000 lb. Similarly, maximum payload rises by 300 lb, to 5,800 lb. To help achieve these ratings Ford beefed up the rear frame section with steel that is 10-17% thicker than the previous model, and added a new rear cross member and additional gussets in high-stress areas. The front frame section is boxed to increase strength and stiffness.

Since 80% of Super Duty owners install aftermarket trailer brake controllers that allow them to modulate the electric brakes fitted on large trailers and campers they tow, Ford decided to develop its own integrated unit and offer it as an option. Unlike aftermarket systems that use comparatively inaccurate internal pendulums or inertial sensors, Ford's trailer brake controller measures actual braking pressure inside the truck's master cylinder and uses that along with information from the ABS system to coordinate the trailer's braking action to match that of the truck's.

POWERTRAIN. The Super Duty gets a new base engine: the 300-hp, 5.4-liter, 3-valve Triton V8 that debuted in the F-150 last year. The aluminum 3-valve cylinder head design also migrates to the Triton V10, boosting horsepower by 45 hp to 355 hp and raising peak torque from 425 to 455 lb.-ft. The third engine choice, a 325 hp, 6.0-liter Powerstroke diesel supplied to Ford by International Truck and Engine Corp., remains largely the same as in the previous model though revised mapping in the electronic engine control system allows it to crank out an extra 10 lb.-ft. of torque for a total of 570 lb.-ft. The five-speed TorqShift transmission that was mated only to the Powerstroke diesel when it was introduced in 2003 is now available across the line-up, and features a "tow/haul" setting that holds gears longer to reduce "hunting" and optimizes engine braking on downhills.

SUSPENSION AND BRAKES. On the four-wheel-drive versions of the F-250 and F-350, Ford replaces the front leaf spring suspension with a newly designed monobeam coil spring setup that reduces the vehicles' turning circle by an average of 5.5 ft. It also updates the steering gear by tightening tolerances in the geometry and adding new internal valving to improve steering feel.

Standard wheel diameter increases from 16 in. to 17 in. giving Ford's engineers the space to enlarge brake rotors by 5% to 347 mm in the front and 340 mm in the rear, providing more braking surface to help dissipate heat. New more durable brake pad material adds 50% more brake lining life to single-rear-wheel models and doubles it for dual-rear-wheels versions.

By Kermit Whitfield, Senior Associate Editor