Whether you're transplanting a big-block into a small-block chassis, or an LS1 into a wimport, ordering up a custom driveshaft is a must for any engine swap project. In addition to changing the distance between the transmission and rearend, engine swaps bring hundreds of extra horsepower to the party. As one of the most highly stressed components in the entire driveline, if the driveshaft snaps in half, you'll be putting down exactly 0 hp to the rear wheels. How's that for parasitic driveline loss? Moreover, increases in horsepower, vehicle weight, and tire grip exacerbate the stresses that the driveshaft endures. With a 775hp big-block, a drag-style four-link, and sticky Mickey Thompson meats, our '93 Mustang project car is guilty of all three offenses.
For assistance in solidly linking together Project Fox's stout Phoenix TH400 trans and built 8.8-inch rearend, we called up Strange Engineering for some advice. After taking a few quick measurements and discussing the needs of our particular application with Strange, they got busy building us a custom 3-inch chrome-moly driveshaft and had it on our doorstep in less than a week. From our discussion with Strange, it became very obvious that a driveshaft is more than a simple piece of round tubing spinning inside a trans tunnel. There's actually quite a bit of science involved when it comes to minimizing vibrations, and maximizing strength and durability. Selecting the right driveshaft for any application requires understating how tubing diameter, material, and wall thickness-in addition to U-joint and yoke design-all impact driveshaft dynamics and strength. Rather than merely stabbing our new Strange driveshaft into Project Fox and marveling in our ability to pull off such a challenging feat, we'll take a crack at explaining the technical aspects of driveshaft design.
While the car was on the lift, we figured it was also a great opportunity to set up the pinion angle. The procedure for dialing in pinion angle differs depending on rear suspension design, but nonetheless, it can be accomplished with a few simple handtools and is critical for keeping rearend wrapup in check under acceleration. As always, thanks to the good folks at Bill Buck Race Cars in Austin, Texas, for helping us out.