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1973 Chevy Pickup Truck - A.S.I.mple Approach

Off Roading
Kevin Blumer | Writer
Posted May 1, 2008

T.I.B. Meets S.B.C.

If you're a Ford fan, you know that the twin I-beam front suspension is one of the most durable designs ever fitted to the front of a desert truck. If you're a Chevy fan, you know that Chevy small-block motors are powerful, easily modified, and as common as Starbucks Coffee locations. Why not combine the two?

Crack kills, and Jeff Larson's '73 Chevy shortbed had cracks aplenty when he first brought it to S.I. (Suspension Innovation) Motorsports' Tom McKenzie. The front suspension was cracked, as was the frame it attached to. Rather than patch up what would surely break again, Tom got the go-ahead from Jeff to revamp the front of the truck with a Blue Oval design. The framerails were plated with 4130 chrome-moly, and the stock suspension crossmember was nixed and replaced with a custom configuration crossmember also rendered in aircraft-grade chrome-moly. The front of the frame was revitalized and stronger than ever.

With the foundation in place, Tom created a one-off twin I-beam front suspension for Jeff's Chevy. Differences in frame dimensions and chassis contours meant using an off-the-shelf S.I. Motorsports F-150 system wouldn't work. What's on these pages was built specifically for this truck. Tom used kingpin 'beam ends for durability unmatched by ball joints. Ford 1-ton spindles pivot at the ends of the 'beams, capped off by Sandy Cone hubs.

"Jeff wanted to save money where he could," Tom revealed. "We could have used 2-inch bolt-on snouts instead of stock 1-ton parts, but this was an area where we were able to take a more economical approach and still have a front end that was strong enough."

At this point, Jeff's Chevy was well-equipped up front but still lacked a durable rear suspension system. The truck headed back into the desert with the S.I. front end and a time-bomb rear end. The heart of the time bomb was a stock Chevy 12-bolt rear axle and stock-length leaf springs. Jeff's luck played out for a whole year before the time bomb went off, and the 12-bolt housing failed. He could have merely replaced the 12-bolt rearend with a custom-braced Ford 9-inch, but Jeff knew that the truck would be better off with a rear suspension that was up to par with the front.

As soon as the schedule opened up at S.I. Motorsports, Jeff's '73 was back under the knife. Tom deleted the broken 12-bolt, leaf springs, and existing rear 'cage work. The truck's tail section now a blank slate, Tom custom-designed and built a four-link suspension. The framerails were kicked upward to facilitate more bumptravel. The 12-bolt was replaced with a Currie-built Ford 9-inch. The rear 'cage was redone to complement the new rear suspension and to match the strength of the tubing that Tom had already placed in the engine bay and in the cab.

The S.I. treatment didn't stop with suspension and 'cage work. Tom's meticulous nature is evident throughout the truck. The 'cage is not just painted, it's powdercoated. The backsides of the fiberglass fenders, bedsides, and hood are coated with Line-X for lasting good looks. The firewall is also coated with Line-X; noise reduction and reduced in-cab temperatures are the payoff.

A premium chassis is more fun when infused with an equally premium motor. As stated earlier, Chevy small-block engines are as common as Starbucks locations. They're also available in several sizes and flavors. Jeff decided to use a 400 small-block for his powerplant. The 400 is more commonly used in drag-racing applications, and as the author personally found out (see sidebar "The Left Seat"), this motor is built and tuned to launch the chassis at warp speed. Backing the 400 is another 400 - a built Turbo-Hydramatic 400 transmission. The TH400 has long served as a benchmark for a durable, economical transmission. Jeff's Turbo 400 is built with a manual valve body and is controlled via an Art Carr gated shifter.

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