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2008 Ford F450 Super Duty - The Seventh Of Its Kind
A 6x6 Ford Super Duty That Pulls More Than Its Own Weight |
By: Mike McGlothlin
Photography by: Mike McGlothlin, Jason Sands, Chuck Chaplinski
Reprint from www.dieselpowermag.com
Believe it or not, this is the seventh six-wheel-drive Ford that Chuck Chaplinski has built. He first concocted
the fully functional tandem-axle setup 25 years ago and fitted it to an '83 F-350. With this first prototype he
learned that the second rear-axle angle positioning had to be just right, the roller bearings on the output shaft
of the transfer case needed to be replaced with tapered ones, and the transmission's Spicer yokes needed to be
tempered steel. After fine-tuning that first truck, subsequent Fords were fitted with the same basic cab-back setup.
Essentially, the back half of the '08 Super Duty's chassis you see here is more than a quarter of a century old.
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Thirty-five years building gravel-handling equipment in the concrete industry has thoroughly familiarized Chuck
with one thing-how to work with steel. Couple that with an innovative mind, and you get one extraordinary truck. To
make the 6x6 functional, a custom-fabricated torque-splitter divides the power that is sent to the 11 1/2-inch AAM
rear axles, which have been part of the setup since 2003. The top driveshaft goes through a carrier bearing that
utilizes an additional U-joint on top of the first rear axle and runs into the second axle, which is tilted slightly
upward to provide the least stressful operating angle. Both rearends have Gov-Loks and 4.88 gearing.
Doing everything he could to keep the rearend cool, Chuck outfitted both rear differentials with Mag-Hytec covers,
and fabricated a unique cooling system. The front axle is equipped with a remote pump that is belt-driven by the
driveline and circulates gear lube fluid out of the front axle, through a cooler mounted in the middle of the truck.
The cooler kicks on when temperatures reach 140 degrees F, and shuts off once the fluid has been cooled below 80
degrees.
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A 12-volt electric over-hydraulic ram system lifts the bed. The 8-inch air springs (2 per rear axle) go into a
3/4-inch line, which feeds into a compression chamber Chuck built out of 1/4-inch steel tubing to compress the
air. |
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The rear driveshaft feeds into a custom-fabricated torque-splitter in front of the first rear axle. A 1:1 gear
ratio transfers the rotation to an upper driveshaft that runs through a carrier bearing to the second rear axle. |
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The rear axle differential is tilted upward slightly to adapt to the angle of the driveshaft. |
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The 24,000-pound Super Glide fifth-wheel hitch is equipped with a load cell that reads the amount of torque the
truck is getting to the ground while towing a trailer. Notice the 25-gallon auxiliary fuel tank at the rear of
the bed. |
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Incorporating the bed onto the truck required a lot of work. Chuck redesigned the bed in 1999 by fabricating the
wheelwells and fenders from thick 12-gauge steel instead of fiberglass. The bed hinges in the rear, and lifts via a
12-volt electric over-hydraulic ram system. Separating the frame from the bed required an innovative subframe that he
welded under the bed. In order to get the proper clearance between the bed and rear bumper when articulated, Chuck
had to lower the rear bumper 4 inches. Inside the bed is a 24,000-pound Super Glide fifth-wheel hitch that automatically
moves back and forth when cornering to protect the front spoiler.
The addition of a Gear Vendors Overdrive to the factory 5R110 transmission has been very rewarding, as it increased
Chuck's mileage from 8.1 mpg to 11.1 when empty. Chuck reports the 6.4L Power Stroke's mileage increased even more thanks
to an OttoMind tuner from Banks. While even the 12.2 mpg he now gets doesn't sound very economical, you have to remember
that Chuck's truck weighs a whopping 12,500 pounds when empty!
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From the rear you will notice that the truck is as narrow as a single rear-wheeled Super Duty. Chuck chose the
11 1/2-inch AAM axles because they were the right width and are pretty stout units. In order to have enough
clearance when the bed was tilted, the bumper had to be dropped 4 inches. The lights spanning across the rear
make good use of the extra space between the tailgate and bumper. |
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Chuck's mileage increased from 8.1 mpg to 11.1 mpg and the 6.4L Power Stroke increased even more with a OttoMind
tuner from Banks. |
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The new compound-turbo Power Stroke sits in the packed engine compartment and benefits from a Banks air cleaner
and OttoMind tuner that's good for up to 120 hp. |
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A whole slew of gauges allow Chuck to monitor his transmission, exhaust gas temperature, and air pressure temperatures.
The monitor on the right gives him a clear view. |
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The first step in outfitting a new truck with the tandem-axle setup is the removal of the bed, driveline,
emergency brake cables, hydraulic brake lines, fuel tank, and exhaust. |
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From there, Chuck measures out and clamps down the frame jig he designed to the frame. Believe it or not,
the frame is cut with a sawzall. He stated that it takes one sawzall blade per side. |
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Before mounting the bed and tandem setup he adds a 3/16-inch steel liner to the factory frame for increased
strength. |
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For Chuck, it was never about creating the ultimate pulling machine, it was about turning heads and having
something unique. "I wanted to have something that no one else has." His perfectionist attitude and
hands-on approach toward tackling such a task is admirable, especially since he's built seven trucks this way.
When we had the chance to meet Chuck in Indiana, he told us that this may be the last truck he builds. But, as
unlikely as it would be for Ford to stop building Super Dutys, it's even more unlikely for them to offer a
tandem-axle option. We optimistically hope Chuck reconsiders. We'll just have to wait and see what he does
when the Super Duty is redesigned in 2010.
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Quite the perfectionist, Chuck said that the frame has to be within two thousandths of an inch of being level
or he doesn't go any further with the project. |
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The factory truck squatted noticeably when towing this triple-axle box trailer... |
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...but no longer does, as it frequently tows this 22,000-pound, quadruple-axle camper down the road. Chuck
stated that an automatic leveling valve on the rear axles keeps the truck level when towing. |
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