As much as most of our stories about the fun of trucks, whether you’re lifting them high or pushing them to the pavement, their very nature is work. And when it comes to heavy-duty trucks that typically involves hauling heavy loads or trailering.
All of the manufacturers’ three-quarter-ton and one-ton trucks are designed to pull their share, but they can’t fight the laws of physics when it comes to standing up against max-capacity loads. Air Lift has been trying to do just for nearly 70 years, using air springs to provide load support to reduce weight-induced squat at the rear suspension.
We’re not likely telling you anything you don’t already know, but what’s new these days is its LoadLifter 7500XL (7,500-pound load-leveling capacity) system just developed for heavy-duty pickups. It uses larger, 7-inch-diameter springs, rather than their conventional 6-inch springs—a 20-percent increase in volume within the springs. The advantage these larger springs offer is the same load-leveling capacity, but with a greater range of adjustability and greater ride quality.
| Here are the springs and hardware for our Air Lift LoadLifter 7500XL kit, which includes the air springs, mounting brackets, airlines, and all the necessary hardware. Depending on the retailer, it can typically be had for $450 or less.
In short, the larger springs do the same job, but at a lower air pressure in the springs. That means the ride is significantly softer—well, as soft as it’s going to get in a loaded heavy-duty truck. Let’s just say it’s a more comfortable ride.
If you’ve ever driven a loaded heavy-duty truck with air springs complementing the original leaf springs, you’ll understand the difference they make in driving confidence. The ride is better and the vehicle feels more controllable, whether it’s a fully stocked bed or a loaded trailer.
We’ve outlined the basic installation for the kit here. It was performed on a ’17 Ford F-350 dually, but the general procedures are similar for RAM and GM trucks. It’s not a nut-by-bolt instruction guide, but an overview of what’s involved. The best part? It’s a true do-it-yourself project. The only drilling involved was to mount the airlines’ Schrader valves. Apart from that, it was all a bolt-in affair. But we’ll be honest. Access to a lift makes a world of difference. We had one, which helped trim the installation time to just about three hours. It’s a good weekend afternoon project that will deliver immediate results the next time you hook up your trailer, including gooseneck and fifth-wheel trailers. And believe us, if we could handle this installation without a trip to the emergency room, so can any other enthusiast with opposable thumbs and a toolbox.
| The 7-inch double-convoluted springs themselves are built like tires with reinforced two-ply fabric for maximum strength. They’re adjustable from 5psi to 100psi, offering a great balance of load-leveling capacity and ride comfort. The larger-bellows springs deliver the capacity of smaller springs at reduced air pressure.
| The project kicks off with assembly of the air springs’ bracketry, starting with installing adjustable swivel fittings for the airlines with a little Teflon tape on the threads. The fittings will be clocked appropriately for the lines after the springs are installed.
| Next, we bolted upper and lower mounting plates to the spring assemblies. The plates are steel, but the springs’ end caps that bolt to the plates are made of corrosion-proof nylon composite.
| With spring assemblies complete, work moves to the truck’s chassis and removing the factory jounce bumpers. The air springs will take up the bumpers’ space. The trick here, however, is raising the vehicle so the suspension droops, which allows the springs to be inserted. That means a lift that lifts on the frame or jack that stands tall enough to hold the vehicle at the frame with the wheels off the ground.
| These studs are mounted on brackets that clip into the frame and are located under the jounce bumpers. Remove those, too. A simple nudge with a flat-blade screwdriver is all it takes to dislodge and remove them.
| New clip-in universal nuts are slipped into the same positions in the frame as the jounce bumper studs. Again, a little persuasion with a screwdriver is all it takes.
| The upper mounting brackets bolt into the universal nuts with carriage bolts. The brackets are different for the left and right sides, so it’s important to double-check the instructions before cinching down everything. The studs in on the bracket, seen here, will mount the spring assembly.
| Next—and simply enough—set the lower brackets in place. They should be flush against the leaf spring stack and locked around the stock U-bolts.
| The springs push up into place and sandwich in-between the brackets.
| There is little room at the top of the spring brackets to tighten the hardware and an impact definitely won’t fit, making it a slow, half-turn-at-a-time procedure.
| The U-bolt attachment hardware slips around the jounce bumper strike plate and spacer block on the leaf spring stack, sliding into the mounting holes of the lower bracket.
| Long carriage bolts hold lower clamps against the bottom of the axle tube and bolt to the bottom spring brackets. Trimming the bottom of the bolts may be required on some vehicles equipped with a rear stabilizer bar. Fortunately, that wasn’t the case with our project.
| Lower leg adapters are included with the kit to support the bottom brackets against the axle tube. We initially slipped them into place with a somewhat loose bracket before they were tightened.
| Heat shields are included to protect the air springs and airlines from the exhaust system. We bent the tabs on them, as shown, to provide at least a half-inch of space between the exhaust pipe or resonator and the shield.
| The heat shield simply attaches to the exhaust system with worm clamps. In our case, that meant placing it around a resonator on the passenger side, which was only a couple of inches from the air spring.
| Here’s one of the installed air springs. Apart from some tight confines for turning the hardware, the project has gone very easily to this point. Depending on the vehicle model and model year, there may be some bracket interference with other chassis lines and hoses, such as the brake lines, requiring the lines to be held away with nylon ties. There were no major issues with our Ford project vehicle, though.
| Time to route the airlines, which simply run from the swivel valves at the top of the spring assemblies along both sides of the frame. There are two choices for the end points: inside the rear wheel openings or at the rear of the vehicle.
| The dually’s wide fenders would have made the rear fender location a little more difficult, so we opted to run the airlines to the rear bumper, necessitating a couple of holes in the bumper.
| The Schrader valves were mounted discreetly on the bottom of the bumper, which also provided easy access for air fills. And with the valves for both springs mounted at the rear bumper, it is more convenient than having to go to both sides of the truck for fender-mounted access.
| With the airlines installed, we tested the system by inflating the springs to 30psi. After that, the connections were sprayed with a soapy water solution to check for leaks identified by bubbles. We deflated the springs to the minimum pressure to restore the original ride height (no lower than 5psi) and checked the pressure again after 24 hours. According to Air Lift, a 2 to 4psi loss is normal after the initial installation, but if it’s more than 5psi, check the system again for leaks.
| Here’s the final installation. Nothing but hand tools and a couple drilled holes were needed for the project. It’s a meaningful enhancement for trucks that work for a living, offering a more comfortable, confident driving experience with a loaded bed or trailer. Not bad for a little more than $400 and an afternoon’s work.