Legions of American car enthusiasts enjoy (or would like to enjoy) boasting of owning (or having owned) a car with Positraction. See how it rolls off the tongue? It’s a spartan one-word expression, bursting with masculine hard consonant sounds.
Unfortunately, few cars during the heyday were actually available with Positraction. Here is a handy list of all car models which offered it as an optional extra:
Notice any commonality here? That’s right, they are all Chevrolets! No other automobiles (except Canadian Pontiacs with Chevrolet drivetrains) came with the alluring and mystical Positraction, the feature mythologized in song:
My four-speed, dual-quad, Positraction 409 – The Beach Boys, 1962
What was this magic elixir that was Positraction? It was simply an optional limited-slip differential introduced by Chevrolet for 1957.
Volkswagen had been offering a ZF limited-slip differential since the early 1950s, but Chevrolet and Studebaker were the first U.S. manufacturers to offer such an item. Studebaker’s offering was sold under the less-sexy name Twin-Traction.
Other manufactures quickly followed suit with Pontiac offering Safe-T-Track in 1958. The following year saw the introduction of Ford’s Equa-Lock, Mercury’s Power-Transfer, Lincoln’s Directed-Power and Chrysler Corporation’s Sure-Grip.
In 1960, Oldsmobile debuted Anti-Spin and Buick, Positive Traction. By 1962 Cadillac owners could avail themselves of a Controlled Differential.
None of these other marketing monikers mattered however, because in June of 1962 The Beach Boys released their immortal 409. As soon as the song landed in the Billboard Hot 100, every hotrodder, car nut and adolescent male wanted a car with the magic elixir of Positraction, even if many of them had only the foggiest idea of what it was.
“Why this here ’64 GTO auto-MO-bile has the original Tri-Power, 4-speed, and Positraction!”
Of course, Pontiacs never came with Positraction. They came with Safe-T-Track. Your buddy’s ’65 K-Code Mustang doesn’t have Positraction, and likewise neither does that ’66 Oldsmobile 4-4-2 you spotted last month.
Major auction houses usually get it right, but not so with the average Joe. Or Hollywood: In My Cousin Vinny, Marisa Tomei testifies that dual equal-length tire marks revealed in an evidence photo could not have been made by a ’64 Buick Skylark “Because Positraction was not available on a ’64 Skylark.” However, the Skylark was available with Buick’s Positive Traction, a fact apparently unknown to the prosecution.
Thus to this day, the majority of American cars fitted with a limited-slip differential are consistently claimed to be endowed with Positraction or it’s casual diminutive, Posi. But unless they are wearing a bowtie badge, they don’t have it.