The F-250/350 Super Duty frames are made using thick 6.7 mm steel outer rails, and the F-450/550 gets 8.1 mm steel. The cross members are both welded and riveted, a belts-and-suspenders approach that Ford says tops the either/or approach of competitors.
The front section of the frame is fully-boxed, for maximum strength, which is critical for customers such as landscapers, who may mount a snow plow on the trucks, said Reyes. The entire frame is e-coated for corrosion resistance.
A significant detail of the frame’s construction is that the very front frame horn section drops down seven inches to mount the bumper. This puts the Super Duty’s front bumper in better line with the protection systems in passenger cars, so that in the event of a collision the occupants of the car are less likely to be injured. High bumpers and stiffer frames can worsen the effects of collisions between different-sized vehicles, so the front frame horn not only lowers the bumper nearer to car height, but it is also constructed of dimpled steel that will crush in accordian-style in a crash to reduce the force of the blow.
With this virtual bridge truss as the foundation, Ford installs suspension appropriate to the expected work load. Two-wheel-drive F-250s and 350s rely on the ol’ Twin I-Beam swing axle suspension used by Ford since the Iron Age. In this iteration stiffer bushings and revises attachment links on the anti-sway bars improve ride and handling, and a steering damper reduces vibration. The front portion of the Gross Vehicle Weight is boosted from 4,800 lbs. to 5,250 lbs.
The four-bys get a moonbeam solid front suspension using coil springs and radius arms designed to minimize axle wind-up under acceleration. The design enables a reduced turning circle of 46.1 ft. for the regular cab, long-bed pickups. The two-wheel-drive trucks U-turn in 47.7 ft.
The F-450/550 rides on a solid front axle, either two- or four-wheel-drive, mounted with twin-coil suspension. The solid axle not only provides durability, but its wider track lets the front wheels turn at sharper angles for a reduced turning circle size of only 42.3 ft. for the regular cab. The big crew cab long bed F-450 pickup turns around in 51.5 ft.
The rear suspension is the business end of any pickup truck, so Ford put some extra effort into this area. The seemingly contradictory requirements of both higher payloads and increased personal use -- which means customer demand for better unladen ride -- posed an obstacle, but vehicle dynamics supervisor Dan Gompper’s Super Duty team scaled it like a Super Duty 4 x 4 conquering the slimy mud of a south Texas construction site in an ice storm. That means they met the seemingly impossible task with poise and determination that prevailed impressively.
Leaf-sprung solid axles have known pros and cons. They are strong and have excellent load-carrying capability, but are given to rough ride and axle-hop under hard acceleration. The solution was longer leaf springs. The new trucks’ leaves stretch eight inches more to mount farther forward on the frame. These longer springs have fewer leaves, contributing to a smoother ride. Stiffer bushings meanwhile contribute better roll control in cornering and the staggered shock mounts provide an improved ratio for the shocks’ damper action.
This rear suspension was also designed to keep the rear of the trucks low to better tow fifth-wheel and gooseneck trailers.