Building a Foundation

Maurice Olley creates a new, fully competitive chassis to undergird the first Corvette

June 30, 2016
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That Chevy’s engineers were able to fit all the necessary machinery inside the upcoming C1 Corvette’s tightly wrapped outer skin was a tribute to both chassis engineer Maurice Olley and Styling Staff member Robert McLean, who created the C1 package. Code-named “Project Opel,” the sports car was being built in 1952 for the 1953 Motorama under Shop Order, or SO, 1737.

As specified by Olley, chief of Chevy’s R&D department, the new car’s frame design was not an adaptation of the existing passenger-car frame as many still believe. Entirely special, it had boxed side members and a central X-member to assure high rigidity. Often frame stiffness is sacrificed by piercing the center of such an X-member to allow the driveshaft to pass through, but the drive line of the “Opel” was high enough for the shaft to travel above the central crossmembers. Small apertures in the X-member allowed exhaust pipes to travel through. The complete frame weighed just 213 pounds.

While stock Chevrolets had torque-tube rear axles, Olley realized that the Corvette-to-be would have to give that up for a conventional Hotchkiss drive. A torque tube surrounding the propeller shaft was an effective means of controlling an axle’s torque reactions, but a too-short tube, as required by SO 1737’s 102-inch wheelbase, would be mechanically awkward. Instead, Olley relied on the rear leaf springs to locate the axle. That axle was adapted from the standard Chevrolet component and carried by four-leaf springs that were 51 inches long and two inches wide.

For his front suspension Olley turned to that of the production Chevrolet, which had been completely redesigned by Kai Hansen for the 1949 model. It was of a parallel-wishbone layout, with its wishbone centerlines trailing toward the rear. The suspension was used complete with its circular-section crossmember, which was bolted to the front frame horns to complete the structure. Detail design of SO 1737’s suspension and steering was carried out by R&D engineer Walter “Walt” Zetye, who was beginning a near-lifetime commitment to the Corvette.

One-inch Delco tubular shock absorbers were mounted inside the coil springs, which were standard parts shortened to suit the sports car’s lighter front-end weight. A front anti-roll bar was retained, but located higher on the front crossmember than it was on the sedans. Wheel rates of the suspension were 110 pounds per inch in the front and 115 in the rear, about the same as a Ford or Mercury of that era. This met Olley’s goal of a “smooth yet firm suspension” that provided for wheel deflections of 7.0 inches in front and 5.0 inches in the rear. “Rebound straps are fitted,” said the engineer, “to prevent excessive joint angles in the propeller shaft, which is only 36 inches long.”

The rear leaf springs sloped upward toward the tail, where they were held by tension shackles, to give about 15 percent understeer effect when the car rolled. “This may appear excessive,” Olley observed, “but some of the handling qualities of a car depend on the amount it is allowed to roll on turns. When a car is designed to roll very much less than normal and with a low center of gravity, so that the overturning couple on the tires is reduced, it may become necessary to put a strong understeering tendency into the rear-axle control to provide an adequate tail for the arrow.” After testing it would prove to be beneficial to reduce the amount of understeer effect given by the rear-spring slopes, but Olley was only being prudent in specifying a powerful effect as a first approximation.

“Aiming the arrow” was achieved by an adaptation of the standard Chevrolet steering. GM’s Saginaw Division made a revised worm-and-sector steering box with its ratio sped up from the standard 19.4:1 to 16.0:1. The steering linkage had a two-part track rod divided at the center, where it was actuated by a trailing idler arm. This had a leftward extension that was pushed back and forth by a drag link from the Pitman arm at the steering gear. As established by McLean, the 3-inch-lower engine position required a new design for the idler arm, which pivoted from a double-row ball bearing. Turns lock-to-lock of the 17.25-inch steering wheel—an inch smaller than standard—were not excessive at 3.7. The wheel sloped at only 13 degrees from the vertical.

Also from Issue 107

  • "Big Tank" '63 Z06
  • C5 Buyer's Guide
  • 461-Cube Stingray Stroker
  • Engineering the Corvette
  • Innovative '58 Restomod
  • C6 Problem Areas
  • Rare-Color '94 Coupe
  • Synthetic Oils Explained
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