Date of publication: 2017-12-29 14:06
At one of the Hershey Antique Automobile Club of America (AACA) shows, a 1959 Chevrolet, Buick and Cadillac were all parked in a row, with their hoods open.
General Motors spokesmen continued to defend the cruciform type frame as offering substantial resistance to side impacts because of the rocker panel and floor pan underbracing members even though by 1965 all General Motors models except the Buick Riviera had abandoned the design in favor of the perimeter type. In 1965 the General Motors technical center offered proof that a unitized structure with side rails can also split into two pieces. A picture of a Ford Thunderbird, torn in half after slamming against a telephone pole and tree, was offered as evidence to critics of the X type frame.
Truly great article. First read about the X-frame when the Malibu v. Malibu vid came out and it 8217 s great to read such a great extrapolation. Knocked another one out of the park, Paul.
Growing up in that era, in a GM-owning family, this is a great topic for me. Thanks Paul. Olds and Buick seemed like the engineering innovators back then. The 8217 89 Buick frame and suspension looks almost like the 8217 57. I had no idea any mass-produced car had all-coil suspension that early. In the 8217 55 8217 s and 8217 65 8217 s, I never liked Olds styling compared to the others, but I can also see that better engineering was underneath.
1959 wagon vs new Silverado truck. Head on collision in the real world. New driver with minor injuries. 59 driver dead, passenger compartment collapses.
I have not attempted to survey the broader influence of aerodynamics on the styling of cars in the latter thirties and up to WW II. Needless to say the influence was profound, and gave us some of the most remarkable cars of the late classic era. But this had relatively more to do with style (and even affectation) than a genuine effort to push the envelope in terms of leading edge aerodynamics. Nevertheless, the benefits and beauty that resulted, like this Pierce Arrow Silver Arrow (above), or Bugatti Atlantique coupe (below) are undeniable, but beyond our scope here. [ Continue to Part 2 ]
Modern car: The passenger cage is designed to be as rigid as possible, so once the crumple zones have been, er, crumpled, the colliding vehicle should stop hard at the A-pillar/front of the door aperture. On some modern cars, the driver 8217 s door could still be opened after an offset-frontal crash.
Old car: the passenger cage wasn 8217 t very rigid, so once the colliding vehicle reached the A-pillar/door it just kept crushing the body structure. Note that the instrument panel bolts to the front of the passenger cage, so once that is compromised the driver was about to get a faceful of steering wheel.
Fascinating! If I ever buy a 8217 58 65 GM car, think it will be an Oldsmobile. Despite the Ford 8217 s perimeter frame having better side impact protection, it would be interesting to see how unitized cars such as a 1958 65 Lincolns fared in the same side crash tests with a tree. For that matter, Chrysler 8217 s later use of unitized construction from 1967 on. Were these more vulnerable than ladder frames from GM?Or were they reinforced sufficiently for a side impact? Just wondering...
Starting with a real stunner: The X-Frame first appeared in 1957, underpinning the new C-Body Cadillacs and Eldorado Brougham (pictured). It was obviously conceived as a way to facilitate lowering the total vehicle height, through deep floor wells for the passengers feet to drop essentially to the bottom of the car, unimpeded by frame rails.
The high strength steels are not as advantageous as the numbers indicate. All carbon steels have the same modulus which means the higher strength steels must deflect or deform a greater degree to acheive their higher tension stresses. Additionally, the higher the steel strength, the less reserve strength is available in the yielding portion of the stress strain curve. It is this yielding phenomenon unique to steel that makes steel so valuable as a structural material.
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