Here’s a deep dive into the engineering behind the all-new 1955 Chevrolet, courtesy of an original General Motors factory film.
The 1955 Chevrolet’s new small-block V8 was such a huge development, both for General Motors and the automotive world at large, that the all-new car it came in is often overlooked. In truth, Chevy’s redesigned body and chassis platform for 1955 represented a huge step forward for GM’s most popular brand. In spite of the division’s success in the early-to-mid ’50s (or maybe because of it) Chevrolet was slipping behind in product development, offering dated hardware that included torque-tube drive and kingpin front suspension. The new ’55 product line moved the bow-tie brand right back to the front.
This nifty little 10-minute film provides some great insights on the engineering behind the ’55 cars. For example, there’s a completely redesigned frame of box-girder construction, but note: the traditional center crossmember is missing. Instead, the body’s cowl section (called a “plenum chamber” at around the 3:15 mark) serves that function—an interesting half-step toward unit body/frame construction. (By the way, we’ve got another, completely different 1955 engineering film from Chevrolet here.)
A series of neat, old-time thrill-show-style stunts are performed to demonstrate the sturdiness of the redesigned chassis, and the new ball-joint front suspension with anti-dive geometry is explained. Also featured are the Saginaw recirculating ball steering gear, and how the rear leaf springs were mounted outboard of the frame rails to increase roll resistance. Hmm. Maybe these details can explain why the ’55-’57 Chevy chassis was a favorite among dirt-track racers for so many years. Enjoy the video. (Please take a moment to click and subscribe to our YouTube channel, where we host our videos for the website and feature lots of great vintage automotive content. Thanks!)
So when we all hacked the firewalls out of our ’55 Chevys, it wasn’t a sound engineering practice? That’s good to know now. Oh well, we are still alive.
Most cars in the last 60 years have used the firewall and plenum as a semi structural piece. And it often takes more than a bit of mods and fab work to replace that strength. And it usually weighs more too.
Though for motorsport moving the engine back and down does achieve better balance.
But then you have to stiffen the body up again.
Those cars being shown all seem to have weak rear shocks, bounce around quite a lot whereas the front seem well controlled.