What is Twin I-Beam Suspension?
Ford’s twin I-Beam system uses two independent beams that work apart from each other, connected by a single pivot point on the opposite side of the frame. The design allows each tire to handle the bumps in the road independently of the other, displacing the force of an uneven road surface along the width of the beam rather than the whole front end bouncing up and down in unison. Each tire's heavy-duty coil springs and shock absorbers on each tire can handle the rebound. Radius arm bushings keep noises to a minimum, as you might get in some straight axle systems.
This front end can handle off-road ruts without wearing out springs or breaking an axle. Radius arms kept the tire centered in the fender, and the camber was fixed to reduce the front-end maintenance Ford truck owners had to do. Ford adopted the slogan - “Work like a Truck, Ride like a Car” to hammer.
What Prompted Ford To Make The Twin I-Beam Suspension?
Before GM introduced independent suspension in 1960, front suspension for pickups consisted of single solid beam axles (mono-beam) equipped with leaf springs that acted as a series of cushion plates. Chevy’s new suspension system allowed for a much smoother ride. Americans began gravitating toward a truck that could ride in the fields and travel on the paved roads sweeping the rural landscape.
When Did Ford Use The Twin Suspension?
The twin I-beam suspension first appeared on the smaller F-100 2WD from 1965 - 84 (Ford discontinued the f-100 in 1983). The F-150 2WD saw it used on their models in 1975 - 96, while the F250 2WD used the suspension in 1986 - 2016. (The I-Beam was also on Econoline vans from 1968 - 2014). While the system went through Ford’s half-ton pickup trucks for the first couple of decades, the heavy-duty three-quarter and full-ton pickups (F250 and F350) continued to use the old mono-beam suspension.
Initially, it was felt that these larger trucks were used less as family haulers than specific work trucks and did not need the more advance, more expensive suspension components. Eventually, Ford realized that it needed to smooth out the ride of the F250 and develop a version for Four-wheel drive trucks (TTB - Twin Traction Beam) since a lot of the buying public demanded it. The twin traction beam system was eventually replaced in favor of a more solid A-frame system that other automakers had used.
Are There Issues With The Twin I-Beam Suspension?
As much as Ford depended on the suspension system over the years, TIB had its share of problems. Since the camber was already fixed and maintenance-free, ride height adjustments were difficult. Owners who wanted to install lift kits found that they had to remove a lot of the front suspension, which created many other issues and did not make owners happy.
Even though Ford intended for reduced tire wear, the engineers found that the opposite occurred. The fact that the front tires handled the ride made the tire rubber wear faster. Some owners also complained about cornering and maneuvering ability of the new suspension system. In some cases, the TIB system led to rollovers when a sharp turn happened at higher speeds.
While the I-beam suspension was cheaper to work on, they were also a pain for wheel alignment issues. Since each tire was independently moving, it was common for owners to have issues with the toe and camber, affecting tire wear. Owners had to rotate tires constantly just to keep tire wear more evenly balanced.
Ford recognized this issue early on and realized that they had advertised that the TIB system would reduce tire wear and front-end maintenance, which was not true in the minds of Ford owners. Their solution was to install more effective, higher-duty shocks, which improved wheel alignment but didn’t solve the problem completely. The excessive tire wear issues exacerbated the rollover issue and made Ford’s new suspension system more of a headache than a technological wonder.
What’s The Bottom Line On This Suspension System?
There is no question that Ford's twin i-beam design that Ford employed improved the ride quality for the trucks more than ever before. As Ford owners began to switch from their solid older models to the new design, many appreciated the softer feel of the front wheels. It seemed as if Ford was really on to something in redesigning their suspension systems.
Unfortunately, the euphoria was short-lived. Even though Ford improved the ride quality, having a twin i-beam front was not without some tradeoffs. While handling was more uniform, and front-end maintenance was less, tires tended to wear faster. Alignment issues abounded, and with the difficulty of camber change, most owners ignored those issues, sometimes to their peril. The truth is that trucks could get away from you, especially if you had worn tires, which was an issue the twin i-beam trucks seemed to have constantly.
Ford was the only company to use the twin i-beam front and eventually abandoned the TIB and TTB suspension systems in favor of the A-frame. Today, only a few classic OBS (Old Body Style) trucks are still on the road with the twin i-beam front suspension, and finding parts for them is tough.
About THE AUTHOR
My name is Matt and I've been around cars all my life! I have owned and worked on many different classic vehicles, so I started this site to share my experiences. If you're new to classic cars, then this website is for you.Read More About Matt Lane