1960-1962 Chevrolet - GMC question

[James B.]

There has bee a puzzle looming at our house about the history behind GM’s decision to use a different convertible car like frame on the 1960-1962 Chevy and GMC light duty trucks along with torsion bar suspension? Then they dropped it all for a more conventional setup in 1963. Some say the X was needed for the torsion bar system but it was anchored to a separate cross brace running between the side rails. Some say that Chrysler sued GM over patent infringement over the torsion bars but I have found no evidence of that in newspapers or legal journals of the time.

This may be one of those urban legend things or someone believing the outcome to drop torsion bars for coil springs was simply plausible stating Chrysler had a hand in it. Truth is, torsion suspension has been around since 1921 in the US and Europe and GM used it on the first generation front wheel drive Cadillac Eldorado and Oldsmobile Toronado. In fact, I don't even find a patent for Chrysler's design used starting with 1956 production of 1957 model year cars.

There was a lawsuit by Czechoslovakian Tatra cars against Ferdinand Porsche and VW for using their torsion bar design and VW lost in 1961 having to pay 3-million DM. The time frame fits but the manufacturers don't.

Any ideas... suggestions as to why GM dropped the working torsion bar suspension for coil springs in 1963? Even if they removed the X brace (and why did they use it for only 3 years) they could have still used the bars like they continued with the rear suspension without the center X brace.

Jim