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Mighty Mopar: 1975 Dodge W100

Posted in Features on August 1, 2011 Comment (0)
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“I wanted to build a Dodge truck for Sand Mountain ever since I was 12 years old,” Cody Bullock said. It took nearly 20 years for Cody to realize his dream, but he wasn’t just sitting around twiddling his thumbs in the mean time. Cody and his brother Cam (AKA Camshaft) spent nearly every free moment of their childhood at Sand Mountain, near Fallon, Nevada.

Cody’s Dodge is street legal, licensed, and insured. The Mopar fanatics went nuts over the truck when he took it to Hot August Nights in Reno last summer. To keep the W100 street legal, the stock steel cab and doors were retained. The Dodge still has full glass, including windshield wipers, so Cody can keep playing in the rain when the buggies and quads head back to the trailer. Chromoly tubing and Dzus fasteners were used to hang the Trailer Products Walker Evans fenders and bedsides on the truck. Fiberglass helps keep the overall weight just over 4,000 pounds; remarkable considering the NP205 transfer case, full frame, steel cab and doors. Most of that weight is up front in the iron block Mopar V-8, as the bed of the W100 is completely bare, save for the 25-gallon Fuel Safe fuel cell, spare tire, and B&M transmission cooler mounted on the tube work.

“It is good clean fun, and kept them out of trouble,” said their father, Gary. The elder Bullock has a ’72 W100 that he bought new off the showroom floor before Cody and Cam were born. That truck now has more than 600,000 miles on it, many of them with Cody behind the wheel and sand under the tires.

While some of his friends became infatuated with dune buggies and ATVs, Cody has always been a truck man. And to be even more specific, a Dodge truck man. In ’96, he purchased the ’75 W100 short bed shown here. Of course, the pickup looked far differently then; it had been sitting for years and wasn’t running, but that kept the purchase price low, and Cody was planning on tearing the truck down to the frame rails anyway.

After years of collecting funds, searching for the best deals on parts, and designing his dream truck, Cody dropped his Dodge off at Samco Fabrication. Samco owner, Sam Cothrun, is a lifelong friend of Cody’s and is better known for building and prepping vehicles that win desert races than for designing sand trucks. However, Sam was eager to be involved in the project and his knowledge of suspension design transferred easily from Baja to Sand Mountain.

Sam’s brother, Wilbur, got involved, as well, helping Cody build the stroked 408ci Mopar small-block under the hood with an estimated 500 horsepower. The stock block was fitted with a Scat steel stroker crank connected to Eagle rods and Keith Black forged pistons. The entire rotating assembly was internally balanced and produces a compression ratio of 11:1, which requires Cody to run a 50/50 mixture of race gas and pump gas to keep detonation at bay. The block is topped with Indy aluminum cylinder heads capped with an Indy single plane, high-rise intake manifold and Carter Thermoquad carburetor. A K&N filter keeps sand out of the carb, while exhaust gasses exit through TTI to dual three-chamber Flowmaster mufflers. The engine is Cody’s Dodge was moved back 6 inches when the when the truck was constructed to provide a better weight balance and ensure that the W100 flies level.

The rear axle is the only departure from the Mopar parts bin, but Cody is quick to point out that there are no true Ford parts on his Dodge. The Spider9 axle housing is fitted with a Strange aluminum third member using 4.88 gears and a spool, as well as 35-spline axle shafts and Dodge brakes at the ends. With no steering concerns or engine to clear out back, the rear suspension design was considerably less complicated. Another pair of Fox Racing Shox 2.5-inch coilovers, air bumps, and Hypercoil springs are used with 150-lb/in over 250-lb/in rates to cycle 18 inches of travel. The triangulated four-link uses uppers made from 1.25-inch, 0.120-wall 4130 and FK JMX14 rod ends that connect to brackets TIG-welded to the center of the Spider9 housing. The lower links are constructed from 1.75-inch, 0.120-wall 4130 chromoly and FK JMX14 rod ends.

Perhaps the most unique aspect of the W100 is the steering. The stock J-arm was retained on the Dana 44, along with the push-pull steering. Instead of being ahead of the engine, the steering box is on the frame rail under the driver seat. Sam Cothrun told us, “This was a fairly common design on Class 4 trucks in the ’80s.” The Delphi Hummer H2 power steering box works in conjunction with a chain-and-sprocket drive that connects the box to the steering column. Sprockets with different tooth counts can be easily swapped to speed up or slow down the steering ratio. A drag link that is constructed from 1.25-inch, 0.120-wall 4130 chromoly and 3/4-inch FK rod ends connects the box to the steering arm.

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The use of a triangulated true four-link front suspension requires the drag link to be the same length as the lower control arms to help eliminate bump steer. A chain drive connects the steering box to the column and allows the tooth count to be changed to speed up or slow down the steering. The front suspension uses lower links constructed of 1.875-inch, 0.188-wall 4130 chromoly and FK JMX 16 rod ends. An additional link built from 1.5-inch 0.120-wall 4130 attaches to the center of the axle and ties in the other two links at the frame end. 2.5-inch diameter 14-inch-stroke Fox shocks stacked with 250-lb/in over 350-lb/in coil springs and 2x3-inch stroke Fox air bumps complete the front suspension. Other than the 4.88 gears and added trussing, the front Dana 44 is basically stock.

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Specs
Vehicle: ’75 Dodge W100
Owner: Cody Bullock
Chassis: Stock with chromoly 4130 cage throughout
Engine: 408ci Mopar V-8, Keith Black forged pistons, K&N intake, Flowmaster exhaust, Scat stroker crank, Eagle rods
Drivetrain: Dana 44 front, Spider9 rear, 4.88 gears, Spool, Strange third member, NP205 divorced, TF727 three-speed auto transmission
Suspension: Custom built four-link front and rear by Samco Fab, Fox shocks and air bumps
Steering: J-arm push-pull setup, Hummer H2 power steering box
Brakes: Dodge disc brakes
Tires/wheels: 37-inch BFG Baja T/A tires, Pro Comp wheels
Interior: Custom carbon/sheet metal dash, Winters shifter, Auto Meter gauges
Other Parts: Trailer Products Walker Evans fiberglass, Pro Comp lights, 25-gallon Fuel Safe cell
Favorite Off-Road Area: Sand Mountain, Glamis, Pismo

While the truck was designed for sand, it can handle the whoops at speeds normally unseen by trucks with solid front axles. Cody did concede that the front driveline is the weak link when the tires return to the ground and the drivetrain is shock loaded.

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