Change often came at a leisurely pace at the Ford Motor Company in the ’30s, but in 1939 the company finally embraced hydraulic brakes.

When Henry Ford introduced the Model T in late 1908, he was arguably the leading technical innovator of the U.S. auto industry, but in later years he was known to dig in his heels. The best example is his stubborn refusal to replace the Model T with a more modern automobile, even as Chevrolet was rapidly catching up in sales with its continually updated products.

Another oft-cited example is Ford’s reluctance to give up on mechanical brakes in favor of more modern hydraulic systems. In the promotion above, a ’37 Ford was parked on a 57-degree incline in a demonstration (a rather misleading one) that the brakes were as good as any. Ford even implied that its mechanical brakes were superior to hydraulic with the slogan, “the safety of steel from pedal to wheel!”

To be fair, Ford wasn’t so very far behind the industry when the company finally included hydraulic brakes in 1939 (above). While hydraulics were introduced to the world by Duesenberg in 1921 and adopted by Chrysler in 1924, a number of automakers chose not to follow along too quickly. One popular alternative was the Bendix Steeldraulic system, essentially an improved cable-operated mechanical setup. For its part, General Motors and its largest division, Chevrolet, didn’t fully embrace hydraulics until 1936.

One reason Ford declined to reflexely follow industry trends was that he often figured he could do better—as he did with the 1932 V8. However, the ’39 Ford used a conventional Wagner-Lockheed system, internal-expanding. Cables to the rear drums operated the parking brake, providing a mechanical failsafe. The master cylinder was under the driver’s floorboard, as was the industry fashion at the time, while inside each of the four brake drums was a slave cylinder and a pair of brake shoes, primary and secondary.

But here the brake operation was not self-energizing; that feature would not appear on Ford passenger cars until 1949. Nonetheless, Ford’s hydraulic brakes were a significant advance over the previous mechanical setup, and often they were among the first upgrades performed by hot rodders as they modified their Model As and early Ford V8s.