Sure-Brake — the computerized brake of 1971

1971 – 1973

The first of its kind, as the record describes it: Chrysler, together with the Bendix Corporation, introduced for the 1971 Imperial a computerized, three-channel, four-sensor, all-wheel anti-lock braking system called Sure-Brake, and the 1971 Imperial is widely described in the automotive record as the first production car with a four-wheel computer-operated anti-lock braking system. The engineering was presented to the Society of Automotive Engineers in 1971 by J. W. Douglas of Chrysler and T. C. Schafer of Bendix. The mechanism was of its moment: a speed sensor at each wheel, a central control box in the trunk, and three vacuum-operated regulators that pulsed the brake-line pressure about four times a second. Popular Science's late-1970 test found the system cut stopping distances on slippery surfaces by nearly 40 percent. It was an analog computer, not a digital one — the first digital, microelectronic ABS was the Mercedes-Benz and Bosch system of 1978 — and the priority claims around it need their neighbors printed: Ford's rear-wheel-only Sure-Track had reached the Lincoln Continental in 1969–70, and the British Jensen FF had carried the mechanical Dunlop Maxaret system from 1966. Within those bounds the description stands: the first production car whose four wheels were governed by a computer against locking.

The market's answer: Fewer than five percent of Imperial buyers took the option; it was offered, at a reduced price, through the 1973 model year and dropped for 1974. The Bendix side of the system belongs in this section with its address stated as the record gives it: the system was the Bendix Corporation's, engineered jointly with Chrysler and published under a Bendix engineer's name; the corporation's brake business was the South Bend works' trade, though by 1971, as the entry above records, the headquarters itself had been gone from the city for three decades and the sources reached do not name the building in which Schafer's group worked. The corporation had walked the aircraft side of the same road earlier — in the 1960s, on the standard company record, Bendix produced an anti-lock system for military aircraft, derived from the established Maxaret line of practice. The electronics age of the brake thus begins, in this record, as a Bendix-and-Chrysler machine of 1971 that the market declined and the textbooks kept.

Sources:

1. "Anti-lock braking system," standard reference record — Chrysler and Bendix's computerized, three-channel, four-sensor Sure-Brake for the 1971 Imperial, available until 1973; the 1971 Imperial as "the first production car with a 4 wheel computer-operated anti-lock braking system."
2. SAE presentation of 1971 — J. W. Douglas (Chrysler) and T. C. Schafer (Bendix), the engineering paper behind the system, as cited in the automotive record.
3. Automotive press record (Popular Science test of late 1970, as carried in the Sure-Brake literature; CarBuzz and Jalopnik retrospectives, 2025–26) — the trunk-mounted control box and vacuum modulators; the near-40-percent stopping improvement on slippery surfaces; fewer than five percent of buyers; the option's 1974 withdrawal; the 1978 Mercedes-Benz/Bosch system as the first digital ABS.
4. Bendix Corporation, standard company record — the 1960s anti-lock brake system for military aircraft.