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(May 04)

Project '67: Part IV

We are about midway through the build on our '67 Chevy project truck. If you have been following our plan—and judg­ing from your response, many of you have—then you know that there were several things for us to consid­er when building this custom truck.

First, we decided to modify the frame and add several suspension modifications (Dec. '03, p. 11). Then we chose a custom wood bed that required extensive alterations to accommodate the modifications done to the frame (Feb '04, p. 12). Finally, we left off with a complete body assembly, which included a total transformation with Good-mark Industries sheetmetal   panels (April    '04,    p.     16). Keeping on track with custom Chevy build, we come to you this month with a very intricate and detailed rearend assembly.

We have only a few major steps remaining before we can reassemble our ride and test the results of our work. Since we elected to use a General Motors LQ4 6.0-liter Escalade engine and the 4L65E transmission (buildup of which is  forthcoming), we found ourselves in need of the appropriate modified rearend. Going in, we knew that the stock '67 rear would have to go, so our goal was to make its replacement as bulletproof as possible. After all, the rearend would have to handle at least 650 hp.

Knowing dnat the stock rearend would not handle more than say, 300 hp, we called West Coast Differentials, which provided us with Sierra Gear 4:11 gears with an Eaton limited slip, as well as West Coast Differentials' axle shafts and bearing kit. Since it was determined that our rear axle housing was considered strong enough to handle the load, we only needed to replace the interior components, as we did not want to make the housing look like a reinforced racecar unit.

It took some figuring to arrive at the best gear ratio for what we were trying to accom­plish. The static gear ratio is calculated by dividing the number of teeth on the ring gear by the number of teeth on the pinion gear. The higher the number, the lower the ratio. But that is only the beginning, as it is how you plan to use the vehicle that makes final selection so important. Of course, if you consider the Gear Vendors over/underdrive, then you can have the best of all worlds—low gear starts, great highway cruising and gear-splitting in between.

Lower ratios are generally desirable when going off-road or for shorter bursts of around-town speed; higher ratios are far more efficient for freeway driving, since they run at lower rpms and in turn offer better fuel economy. It would have made much better sense to install a Gear Vendors two-speed unit in this project, but since we are building a cruiser, we needed only a lot of off-the-line torque. Should we ever decide that this truck will become an over-the-road tourer, in goes the Gear Vendor unit, hands down. Instead, we chose the 4:11 ratio that should cruise at 2,200 rpm at low highway speeds and have awesome power off the line. This is not a best-of-both-worlds installation; it was selected for the brute power it will put to the ground. TB

SOURCES

SUPER DUTY HEADQUARTERS (SDHQ) Dept. TB 525 E. Baseline Rd., Ste. 108 Gilbert, AZ 85233        877/969-2929     www.superdutyheadquarters.com

WEST COAST DIFFERENTIALS Dept. TB 2429 Mercantile Dr., Ste. A Rancho Cordova, CA 95742 800/510-0950 www.differentials.com