When we started project Hot Rod Hauler, our intent was simple enough, we wanted to make our workhorse ’73 Ford 350 a little more comfortable, a lot better looking, and no less of a utilitarian pickup than it was when we started.
It’s always best to use the...
It’s always best to use the largest airbag that will fit. We used DeNominator convoluted bags from airbagit.com that are 6.25 inches in diameter.
In our last installment we slipped a pair of dropped I-beams from airbagIt.com under the front and added a pair of airbags to go along with those in the rear. This time around we’re adding the air management system
Air suspension has been around for a long time. The Cowley Motor Works developed one of the first systems in the early 1900s in England, however it was plagued by leaks and was considered a failure. In the ’30s, Firestone developed a system for the experimental Stout-Scarab, but the expense made it impractical for production. While air suspension still had not caught on, refinements continued.
General Motors began developing airbags for commercial use in 1952 and by 1958 they appeared on some GM cars. Cadillac offered a system that was designed to be self-leveling and compensate for passengers or varying loads in the trunk but in operation these early air systems were often slow to react, if they did at all. And while the ride quality was considered to be good, the controls were so trouble prone that many were removed and the airbags were replaced with conventional springs.
The #2500 DeNominator bags...
The #2500 DeNominator bags have a closed height of 2.8 inches, maximum extension is 10.25 inches and we established ride height at 6.5 inches; capacity is 2,096 pounds per bag and they are rated for 600 psi. Note that these bags have 1/2-inch inlets.
While air suspension got off to a slow start in passenger cars, it grew rapidly in popularity in the truck market. Airbags can be found in the seats and suspending the cabs of trucks to smooth out the ride for over-the-road haulers. Of course, the obvious advantage to airbags is that the suspension can be adjusted to fit varying load requirements—it can support a tremendous amount of weight when necessary without beating up the truck, or the driver, when empty. That’s exactly why we want it in the Hot Rod Hauler.
Since 1992, Joe Morrow has been providing air suspension for just about anything with wheels. His airbagit.com web site offers everything from individual parts up to and including complete plug-and-play kits, that’s why we turned to them to get our F-350 on air.
Along with all the pieces and parts Joe can provide, he also has a wealth of information gathered from years of experience putting systems together. Here, with the help of airbagit.com, is a look at the major components of an air suspension system.
By comparison, these #800...
By comparison, these #800 bags have a diameter of 3.5 inches, a minimum height of 6 inches, and a maximum length of 10 inches. Capacity is 1,500 pounds per axle and they are rated for 150 psi.
According to Joe, the diameter of an air spring is directly related to the pressure required to attain ride height. In other words, a small diameter bag will take more pressure to lift the weight of your truck than a larger diameter bag. A truck with a heavy engine and a small bag could require 160 psi to get to ride height (which would result in a horrible ride), while with a lighter combination and a bigger bag 45 psi would be required (which would provide a much better ride). What it boils down to is this—the less pressure required to lift the vehicle, the smoother the ride. For that reason Joe recommends using the largest bag that will fit into the available space. We used the double-convoluted DeNominator air bags with a capacity of 2,096 pounds per bag on the Hot Rod Hauler.
Ride Height And The Sweet Spot
The sweet spot, as defined by Joe, is the perfect ride quality. However, there are often different expectations from air suspension systems. Some want to be able to lay their truck’s frame on the ground; others want to jack them up, so one size seldom fits all. Airbagit.com designs their kits to lower ride height by 3 inches; to go lower or higher will require custom brackets, which they offer.
Compressors come in a variety...
Compressors come in a variety of capacities, This is a DC 7600 that delivers 4 cfm and has a 3/4-hp motor.
In our experience, the best ride, or sweet spot, has been achieved by making sure the airbags were at the specified installed height with the truck at ride height. All bags have a minimum compressed and maximum extended length, installed height is somewhere in the middle.
Our DC 7500 compressor was...
Our DC 7500 compressor was the plug-and-play version that includes an enclosure. A cover is included but is not in place here.
Electric valves provide much...
Electric valves provide much quicker inflation and deflation of the bags; each valve inflates and deflates one bag. These are brass construction.
These are the valves used...
These are the valves used on the Hot rod Hauler. The big ports are the supply lines to the bags. The smaller fittings below are for the gauges on the control panel.