How Ford’s Ingenious Flex-O-Matic Suspension Helped Sell Trucks To Non-Truck People

One of the biggest challenges with a pickup has always been how to make something that can carry heavy loads not ride like the mechanical bull in Gilley’s when the bed is empty. It’s extremely difficult to have a suspension that allows a vehicle to drive just as well unloaded as it does with 1000 pounds of rocks in the bed. With an empty bed being the worst-riding option, it’s easy to understand why non-truck-enthusiasts considering a pickup truck for everyday use may have decided after a test-drive that a truck was not for them.

The problem of ride quality varying with load is not one without a solution. The modern answer is usually to add air shocks or some other kind of variable system with pumps and hoses that add more weight and complexity, but in the sixties and seventies Ford offered a rather brilliant solution that did the same task in an amazingly simple way.

Ford had already worked up a solution in 1965 for independent front suspension that would give a better ride than a live axle but maintain the rugged durability expected of a Ford truck. The famous “Twin I-Beam” was an innovative solution that many people are well aware of, but how Ford dealt with the rear suspension was just as ingenious, though not as well known.

Dubbed “Flex-O-Matic,” the name alone tells you that it appeared in the mid-century era where everything had to have a Jetsons-like name that included “matic.” Indeed, it debuted in late 1967 on Ford’s fifth-generation F-series trucks, affectionately known as the “bumpside.” Flex-O-Matic suspension was standard on F-250s and optional on other models.

The heart of the Flex-O-Matic was a special pivoting shackle at the back of each rear leaf spring. The shackle stayed in an upward position with lighter loads, allowing it to use a softer portion of the spring rate to absorb minor bumps and give a car-like ride. However, if you loaded a bunch of stuff in the bed, that shackle rotated downward into a secondary, stiffer position to let you handle stiffer payloads.

Here’s a video that demonstrates the system better than words could do.

After the 1967 “Bumpside” series was replaced in 1973 with the sixth-generation “Dentside,” the Flex-O-Matic remained as a feature, at least in the early years of this series. I couldn’t find the exact last year it was offered, but it was certainly well before it was replaced by the boxy seventh-generation in 1980.

You can see the shackles in this Ford parts drawing from a catalog dated 1975, so it was still available at least then:

Why was it dropped? I’ve read various stories. Some say that later multi-leaf springs did the job as well or almost as well, or that optional air shocks were a better solution. My feeling? More than likely, the cost of the extra parts required for the Flex-O-Matic design was deemed not worth the investment when it came time for the inevitable decontenting that was regularly done for cost savings. I can’t prove it, of course, but it would sadly seem like a logical reason.

Before the sixties, most companies really couldn’t care less if a truck was “comfortable.” In many ways, Flex-O-Matic was a major step in making the trucks more palatable to regular consumers as everyday cars, starting a trend that continues to this day.

Like old Ford trucks in general, the Flex-O-Matic just did its job quietly and unnoticed, which is yet another reason why these old pickups are so loved today.

Top graphic image: Ford