Work on the 1958 Chevrolet began in earnest in mid 1955 at a time when the sales potential of the 1955 cars, themselves a radical departure in many respects from their forebears, wasn't fully apparent.
Part of the Bel Air series, the 1958 Chevrolet Impala
was offered as a hardtop or convertible.
Clare MacKichan's design team, along with designers from Pontiac, started to establish basic packaging and dimensions for their shared 1958 General Motors A body in June; the first styling sketch that would directly influence the finished Chevrolet product caught the eye of General Motors Styling vice president Harley Earl in October. Seven months later, the basic design was worked out.
It was a radical change from the 1955-1957 shape that was itself a substantial move away from the conservative Chevrolets of past years. Longer, lower, and wider -- the design mantra of those days -- than its boxy predecessors, the 1958 in any of its forms was a rounded and extroverted design with plenty of visual excitement. The sharp tailfins of the 1957 gave way to deeply sculptured rear fenders. And, of course, 1958 was the first year of dual headlamps.
Underneath this new body was a new chassis. The standard
perimeter-type frame was abandoned, replaced by a unit with rails laid
out in the form of an elongated "X." Chevrolet claimed that the new
frame offered increased torsional rigidity and allowed for a lower, yet
still roomy passenger compartment. In this design, a
transitional step between traditional construction and the later fully
unitized body/chassis, the body structure was beefed up in a number of
areas (most notably the rocker panels and firewall) to create a solid
Triple taillight clusters, seen here on a 1958 Impala
hardtop, would become an Impala trademark.
The rear suspension was redesigned as well. Leaf springs were abandoned, replaced by coil springs. Long, stamped, trailing links located the axle on each side, supplemented by a yoke pivoting on the frame and center of the differential housing. Chevrolet counted up the pivot points and dubbed the result "four-link" suspension. Conventional upper and lower A-arms with coil springs were retained in front. The overall result was good handling and a very soft ride.
A new engine was also part of Chevrolet's program for 1958. The existing V-8, now three years old and up to 283 cid from the original 265 cubic inches, had caught the attention of performance fans from the start and was ideally suited to the light 1955-1957 sedans and Corvette, but engineers wanted something a little larger for the bigger 1958s.
Thus, an all-new engine was prepared, also a V-8, displacing 348 cubic inches. Dubbed the "W" engine, the compact 348 had wedge-type combustion chambers and was initially offered in two states of tune: The basic unit with a single four-barrel carburetor developed 250 bhp, while the "hot" variant with three two-barrel carbs was rated at 280 bhp. (A tri-carb 315-bhp version came out later.)
To follow the story of the 1958-1960 Impala, continue on to the next page.
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