DeLorean and the Pontiac Tempest
Despite the need for a compact, the fate of the fledging Pontiac Tempest seemed bleak. With Corvair variants finding no champions at Pontiac, Buick, or Olds, a new vehicle was needed. Pontiac took the lead in an interdivisional project known as the X-100 program, developing a larger and substantially modified version of the Corvair's Y-body platform.
The wheelbase was increased from 108 to 112 inches and provisions were made for a front-engine layout since Buick and Pontiac were developing engines for it. The basic bodies would be shared, though each division would get unique styling and none would look at all like the Corvair.
Pontiac's director of advanced engineering, John Z. DeLorean, was anxious to put his stamp on the "Wide Track" portion of the project. In order to come in at a competitive price, the compact Pontiac would have to make as much use of existing technology and production facilities as possible. The solutions that DeLorean and his team implemented demonstrated their expertise at working creatively within a clearly defined set of boundaries.
DeLorean wanted a car that was more than just a compact. In addition to offering lower purchase and running costs, the new design needed to possess a "big-car" ride and offer comfortable seating for six adults. The smaller size also suggested an inherent sportiness and DeLorean believed he could meet these objectives, as well as achieve the ideal 50/50 weight distribution by using a flat floor, a rear-mounted transaxle, and, of all things, a flexible driveshaft. Buick and Oldsmobile, however, were not planning on using any such exotica on their small cars, preferring to stick with conventional drivetrain layouts.
The design was truly revolutionary, though not always understood by the public. It soon earned the nickname "rope drive," which was not an accurate depiction of the driveshaft. The shaft was actually a forged-steel torsion bar, which featured high nickel, chrome, and molybdenum content. Tempests with manual transmissions featured a shaft diameter of '75 inches, while automatics received a '65-inch-diameter unit. Since the shafts were transmitting engine torque that was not multiplied by the transmission, they were understressed and could easily afford to be as small in diameter as they were compared to a conventional driveshaft.
The shafts were surface ground and magnafluxed for imperfections before shot-peening and final straightening procedures. The manufacturing process was finished with a rust-inhibiting coating. Obviously, quite a bit of expense went into the development and manufacture of the flexible driveshaft. Its intended benefits to the Tempest will be explained in a bit.
See how Pontiac Tempest revolutionized the compact car with its four-cylinder engine on the next page.