1951 General Motors LeSabre Transmission and Suspension
Harley Earl wanted the 1951 General Motors LeSabre to have an automatic transmission, and while Buick was willing to pay for an all-new engine, creating an all-new automatic transaxle would have been too expensive, even for this costly car. (Estimates put Buick's original combined outlay for the LeSabre and XP-300 at $1 million. This translates into roughly $10 million in today's currency.)
To solve the transmission dilemma, engineer Charlie Chayne took a stock Buick Dynaflow, hung it at the rear of the chassis, and attached the DeDion differential to it.
Somewhere along the line, the Dynaflow gave way to a four-speed Hydra-Matic, and that's what's in the car now. The original double-jointed axle shafts are magnesium, and the LeSabre uses a transverse, single-leaf rear spring. Finned rear drum brakes stand inboard, just off the differential housing.
The front suspension is equally unconventional. It consists of cast-alloy upper and lower A-arms, but the LeSabre used neither coil springs nor torsion bars at first. Instead, the pivot rod for the upper A-arm originally passed through-and was solidly embedded in-a big cylinder of solid rubber. The rubber cylinder had a steel outer casing and, with the rubber in torsion, supported the weight of the front end. So the rubber acted as the springing medium.
Tubular front shock absorbers, meanwhile, mounted to the steel casing up top and then bolted to the lower A-arm below. This system worked pretty well until the rubber started aging and losing its elasticity, after which Chayne installed a set of front torsion bars. (He'd had torsion bars under his XP-300 all along.)
The LeSabre's front brakes consist of finned, double-wide drums. This was before disc brakes became common, and Chayne recognized that the LeSabre needed stopping power to match its speed capabilities.
Since its wheels are 13-inchers to help lower the chassis, Chayne wanted to give the front brakes more swept area than normal. So he doubled the drum width and installed four shoes up front instead of the usual two.
Continue reading to learn about other cutting-edge features of the 1951 LeSabre.
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