The Thunking Man's Car

A small car glided out of an American Motors plant in Kenosha, Wis., drove quietly into the night and braked to a stop in a farm field. There, where the air was clear and city noise was absent, the passengers alighted and began loudly slamming the car's doors. After each slam, the men placed stethoscopes against the car body and listened to the lingering vibrations. Half an hour later, everyone climbed back into the car and returned to the plant.

This midnight ride of American Motors engineers was a regular test in their effort to develop doors that slam with what automen call a solid "thunk." One result showed up last week as American Motors introduced the Hornet, its new small car, with an advertisement that urged: "Open a door and listen for the reassuring thunk you get when you close it." In auto showrooms, the sound of a car door slamming touches some responsive chord in the frazzled psyche of the American buyer--and all the automakers know it. "There is very little to go on when you buy a car these days," says Carl Hedeen, General Motors' chief of body engineering. "If the glove box opens, the seats are soft and the doors thunk, that's all you have over the competition."

Angry Wife. Every year U.S. automakers invest millions of dollars and countless man-hours to produce the thunk that sells. G.M. employs 250 technicians--including graduates of Purdue,

Stanford and Michigan State--to work exclusively on doors. Ford, Chrysler and G.M. test and refine their thunks in soundproof chambers that are sealed like bank vaults. Stereo tapes are used to record the effects that subtle design changes have on the sound. High-speed movies are made to study vibrations, and oscilloscopes gauge the thunk's duration. The automakers also employ automatic slamming machines, which create sounds ranging from what G.M.'s Hedeen calls the "angry-wife slam" to the "husband-coming-home-late-at-night slam." The former is 50 foot-pounds, and the latter three foot-pounds.

Company chiefs like to test the thunks themselves. Chrysler Chairman Lynn Townsend sometimes drives subordinates to distraction by slamming doors repeatedly in the ear-splitting confines of a testing garage. American Motors Chairman Roy Chapin likes to go into his company's executive parking area to try out the thunk. Ford has a jury of product-development specialists to pass judgment on thunks.

The quality of the thunk depends on many factors: the rigidity of the car's body, the locks, the soundproofing in the door, the carpet on the floor. Heavier cars tend to have sturdier thunks, but lighter models can do well if aided by a few gimmicks. Special bracing inside the. door can improve the thunk, but technicians do not know just how or why. "There's a lot of black magic in this thing," says John Adamson, an American Motors' vice president.

What kind of sound do Detroit's acousticians attempt to achieve? At G.M., says Product Engineer Jim Leslie, the goal is "ker-chuck--that's what we want, ker-chuck." Chrysler, says Executive Body Engineer Jim Shank, aims for "the kind of sound you get when you drop a ripe pumpkin in the mud.v The ideal sound for American Motors, says Adamson, is "a clump--not a clink, clatter or clunk, but a clump." Of course, he concedes, "we will never reach the ultimate sound." Undeterred, scientists continue to chase across farm fields by dark of night, stethoscopes in hand, in pursuit of the elusive, perfect thunk.

AUTOMAKERS are perennially optimistic, and this year is no exception. Despite signs of ebbing consumer confidence and new models that are relatively unchanged, they predict that sales of U.S. and imported cars in the 1970-model year will come close to the 9,600,000-unit level of 1969.

Apart from the new small and sporty cars designed to frustrate the fast rise of imports, the 1970s look like and are much like the 1969s. In the year of dej`a vu, the only completely redesigned full-sized car is the Lincoln, which, among other things, now has a body bolted to the frame for a quieter ride. Several cars have more powerful engines; the biggest of all is the Cadillac Eldorado's, at 500 cu. in. The Plymouth Barracuda is one of the few cars that have had enough sheet-metal changes to give the body a new look. The game of hide-and-seek has taken a new turn. Disappearing headlights have been dropped on all G.M. cars except the Corvette, but hidden windshield wipers have been made standard on nearly all cars.

Of course, there have been some changes in prices. G.M.'s are up an average of $125 a car, Ford's $108, Chrysler's $107, American Motors' $81 (though the Hornet, at $1,994, is pointedly priced $1 below Ford's competing Maverick). Automen justify the increases by citing higher production costs. G.M. figures that payroll costs have risen 6% in the past year and will go up another 6% this month under terms of the company's labor contract; steel is up 6%, copper and lead 24%, zinc 11%.

Part of the cost squeeze is of Detroit's own making. It stems from the proliferation of models, options and special features. Ford's general manager, John Naughton, boasts that "we can run our assembly plants at maximum capacity, maximum overtime 365 days a year and not build the same car twice." Ford's Torino, for example, offers a choice of five vinyl roof colors, plus 16 body colors, and 33 sets of interior trim. All that contributes to the more than $2 billion that Detroit is spending to bring out its new models, and denies auto plants the economies of long production runs of identical cars. Automen insist that they are only giving the public what it wants. Nobody wants to revert to the marketing philosophy that the buyer can have a car in any color so long as it is black. But quite a few buyers might be willing to settle for less choice in return for lower price.

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