Rear Suspension Information

Straight Axle Ford F-SERIES Rear Suspension

Choosing the right rear suspension for your Straight Axle Ford F100 is really up to you and the kind of truck you wantto build. Some considerations to ponder: Daily driver or show truck, high horsepower or cruiser, tire width, quality of ride. There are pretty much 3 general choices when choosing a rear suspension.

Straight Axle Ford F-SERIES (F100) Stock Rear Suspension

We’ll start with the stock set-up with leaf springs. This system is fine and all you have to do is make sure all of your parts are in good working condition. Inspect the leaf eye bushings and pins to make sure they’re in good shape. These are often neglected of grease and wear the frame bracket and the spring eye out of round, so inspect them and rebuild as necessary.

We carry the best quality restoration rear suspension rebuild parts for 48-64 F100’s

Easy 9 inch Ford Rear End Swap for the Straight Axle Ford F-SERIES (F100)

One of the easiest upgrades you can make to your Straight Axle Ford F-SERIES (F100) is the rear end/axle. Finding a donor 9 inch Ford rear end for my 53 F100 was pretty easy and inexpensive. It turns out that a 67 Ford F-SERIES has rear end housing almost identical to the stock F-SERIES in terms of how it mounts to the springs and shocks. It is literally a dead on fit to install it in the 48-64 F-SERIES. Leaf spring width, spring perch placement – all matched up. Drum to drum width was nearly identical as well. Stock 1948 – 1964 Ford F-SERIES rims still fit because the 5 bolt wheel pattern is the same for most F-SERIES’s for many decades. Make sure you measure if you choose to go this route because it’s possible that only certain 67 F-SERIES’s had this rear end. I’m not sure. I would assume that some of the 68 to 71 F-SERIES’s would be the same as well. I measured a 72 F-SERIES, but the leaf springs were 1/4 inch wider which makes the spring perches too wide for stock 53 F-SERIES leaf springs. The 9 inch that I found in the 67 F100 was a 28 spline, but worked great for my 302!

Four Link Suspension Systems & Ladder Bars

I consider the ladder bar system fundamentally the same in concept as the four link or four bar suspension system. Four bar systems usually take less room to install than the four link, but are typically not as strong as a four link. Four links are superior for ride and adjustability as well as strength (usually), so we’ll focus on those.

Four link suspension systems come in many configurations, but all are based on the same idea. 4 bars (2 on each side) connect to the rear axle from a front mounting point. It could be a cross member or frame rail mount bracket. Keeping side to side movement in check is a bar called a panhard bar, or it can be called a track locator. Several companies offer systems and they vary in a number of ways. 4 bar tube diameter, rod end size and quality of components basically determine how much abuse the suspension system can take. For example, 1-3/8 inch diameter 4 bars typically take more abuse than 1-1/8 inch diameter versions (if material quality is the same). A strong front mounting bracket or cross member is critical because everything is attached to it. Quality spherical rod ends are equally critical because these can easily be a weak point in the system. The spherical rod ends may have to endure a lot of abusive torque. Mild-steel rod ends will work in lower horsepower applications while chromeoly rod ends should be used for high horsepower applications. It’s also important to note that the lower bar on each side of a four link puts a lot of stress on the front mounting point when you launch your F-SERIES. The rear end (pinion) torques upward and pushes the lower bars forward on the mount. The mount should be reinforced well if you’re running big horsepower.

Some rear 4 bar suspension systems for the Straight Axle F-SERIES’s mount to each frame rail and don’t rely on a cross member for connection. They basically are installed where the original leaf springs are. They typically bolt to the frame and are fairly simple to install. You will most likely have to weld the connection between the rear end to the brackets that attach to the 4 bars. These are fine systems, but limit tire width, similar to a stock leaf spring set-up. One advantage to the geometry of the frame rail mounted 4 bar suspensionsystem is that it puts the 4 bars on the outside of the frame rails. That widens the 4 bar location and wider is better.

F100 Central offers a few different 4 bar suspension systems. No Limit’s version uses longer bars and I favor it over the others. Click here to visit the 4 bar suspension parts available.

If you are pro streeting your truck with fat tires, you might as well buy a “fit anything” four-link suspension system as the street rodders do. There’s not much reason to buy a system built specifically for your 1953, 1954, 1955 or 1956 F- SERIES. You still have to take into consideration how tough the system has to be to handle your right foot launches.

There are many spring options available for 4 link suspensions. Integrated coil-over’s with shocks are the most common. Spring rates are important and companies who sell springs can help you with the correct rate and length of spring. Coil-over’s usually bolt to a cross member on top and to brackets that are welded to the rear end. Some mounts come with several holes to adjust ride height by using different sets of holes. Now, companies like Air-Ride Technologies have brought air bag suspensions to the forefront of street rodding. Air bags can usually be substituted in place of coil-over. When set up correctly, air bag suspensions are great performers – never thought of your F100 as a track truck? Air bag suspensions also allow you to lower your truck at a show and raise it up to drive it home.

Corvette Independent Rear Suspension for 53, 54, 55, 56 F100 (F-SERIES)

There is nothing better than a Corvette independent rear suspension in your 1953, 1954, 1955 or 1956 Ford F-SERIES F100. It’s by far the best ride and looks the coolest! In the past, people have adapted Jaguar and Corvette independent rear suspensions on their own. Now bolt-in rear suspension kits are available to set-up a corvette independent rear suspension on your 1953, 1954, 1955 or 1956 F100. Flat Out Engineering provides the kits for several different trucks including the 53-64 Ford F100. We are a dealer of Flat Out Engineering Corvette suspension kits. Yes the cross member and all mounts bolt right in – easier than you might think. Then just take a Corvette Independent Rear Suspension out of a Corvette and install it in your truck. You can weld some of the components in if you choose to.

Check out the Corvette IRS parts here. Flat Out Engineering has assembled these install kits to make the Corvette suspension install go as easy as possible.

If you’re putting Corvette IRS out back, you might as well put Corvette Independent Front Suspension up front.

See how to install a Corvette independent rear suspension in a story on the Classic Trucks magazine website.