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Eliminating Suspension Squat With Airlift’s Loadlifter 7500 XL System

The mountain-moving capability that lies within a late-model Super Duty is staggering. Even an F-250 can tow more than 18,000 pounds when properly equipped. But even though the 6.7L Power Stroke and TorqShift transmission combo is more than ready for any task (no matter the weight), the rest of the truck can be the hold-up. Case in point, the owner of this ’18 F-250 recently bought a fifth-wheel toy hauler and the corresponding B&W hitch to couple it to, only to realize the ¾-ton’s factory suspension was a bit outmatched. As a result of a squatting rear suspension, the truck’s handling and braking functionality was compromised, body roll became noticeable, and its headlight aim was undesirable, especially for oncoming traffic.

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To allow the truck to live up to its full towing potential, the owner decided to install air springs. And leaving nothing to chance, he sprang for AirLift’s top-of-the-line LoadLifter 7500 XL system—a system that provides up to 7,500 pounds of load leveling capacity. To control the air springs, AirLift’s Wireless Air EZ Mount package was also selected. The driveway install consumed a full, 8-hour day, but proved more than worth it, as the truck now tows the 16,000-pound fifth-wheel in a level, more stable manner, with reduced body roll, no more bottoming out, and vastly improved steering and braking performance.

Comprehensive to say the least, the AirLift LoadLifter 7500 XL system includes both air springs, all necessary mounting brackets and hardware, a roll of Nylon air line, and a fully-illustrated, highly-detailed installation manual. Everything is intended to bolt directly on to a ’17 or newer F-250, F-350, or F-450 Super Duty without the need for any drilling. This would prove to be the case in our install.
AirLift’s LoadLifter 7500 XL (7,500-pound) air springs are about as close to what you’ll find on a Class 8 truck as it gets in the pickup truck aftermarket. They measure 7-inches in diameter and offer 20-percent more volume than the company’s LoadLifter 5000 springs, along with providing more leveling power with less pressure. Their rigid yet pliable construction resembles that of a commercial-grade tire, with layers of rubber and cords used to help control growth.
With the truck’s rear wheels and tires removed, jack stands positioned under the receiver hitch, and the floor jack left under the differential for added safety, we got started by removing the factory bump stops. Then the clip-in studs were finagled out of the frame by prying on the hinged ends with a flathead screwdriver.
The OEM clip-in studs used to mount the bump stops were replaced with slide-in, universal nuts supplied by AirLift. They facilitate the install of the air spring assemblies’ upper chassis brackets, which anchor to the frame using the included M10 x 1.5 x 35mm button-head cap screws.
Next, the swivel elbow fittings were installed in the top of each air spring. Once finger tight, each fitting was tightened an additional 1.5 turns via ½-inch wrench. Then a roll plate, which is designed to protect the air spring from both abrasion and the elements, was installed on the top of each air spring.
For the ultimate seal, AirLift’s supplied swivel elbow fittings come pre-Teflon taped. This both saves time for the installer and provides assurance that no air leaks will stem from the 90-degree elbow that sits in each air spring.
The upper air spring brackets are secured to the air springs using 3/8-inch hex bolts, lock washers, and flat washers. At this point, we were assembling the left side air spring assembly (driver side). With instructions to torque the 3/8-inch hex bolts no more than 20 ft-lbs, that’s where we set the torque wrench.
After flipping both assemblies over and positioning a roll plate on the bottom of each air spring, we moved on to joining the lower bracket cup (what rides on the lift block perch, or bump stop striker plate) to the lower bracket main plate. From there, the supplied 3/8-inch x 10-inch long carriage bolts were inserted into the lower bracket main plate.
Attaching the lower bracket main plate assemblies to the air springs called for 3/8-inch hex bolts, lock washers, and flat washers. Per AirLift’s instructions, we maneuvered the lower brackets as far forward as possible before torquing the hardware to 20 ft-lbs. Here, the passenger side air spring assembly (on the right right) is sitting next to the driver side assembly.
The final step in piecing the air spring assemblies together is determining which lower leg adapter you need and installing it. Due to three different rear axles being offered on ’17-newer Super Duty’s, AirLift includes three pieces in each kit. After sticking a caliper on our F-250’s axle tubes, they measured 3.5-inches, which meant the 10.5-inch Sterling version included in AirLift’s LoadLifter 7500 XL kit would be employed. Note that 4.0-inch and 4.5-inch lower leg adapters are included, which we presume fit the Dana M275 and even larger M300 rear axle options.
Despite drooping the axle as much as possible, the driver side air spring assembly had to be semi-disassembled in order to get it into place between the axle and frame. Then, once the lower bracket cup was resting on the leaf spring perch, we forced the lower bracket flush against the leaf spring stack. We also made sure that both cut-outs in the lower bracket were locked around the factory U-bolts.
Securing the air spring assemblies to the factory leaf stack called for the use of the supplied U-bolts. We used the center hole in the lower bracket (there are three to choose from) and tightened them up evenly using the included 3/8-inch flat washers and nylon lock nuts.
The next step in attaching the air spring assemblies to the axle entailed installing the lower clamp bar onto the 10-inch long carriage bolts. Once again, 3/8-inch flat washers and nylon lock nuts were used to cinch everything down, and we evenly torqued the clamp bar hardware to the recommended 16 ft-lb spec. Following that, we went back to the previously installed U-bolts, torquing them to 10 ft-lbs.
Making sure everything was tight, especially the nut that joins the lower bracket main plate and lower bracket cup together, we performed a once over for every accessible fastener installed thus far. We’ll also note that while we ran into almost zero issues with the factory brake lines and ABS sensor lines, your particular application might be different. Not to worry, AirLift’s detailed installation instructions spell out virtually every clearance scenario you may encounter at the back of the axle.
Be prepared for close quarters on the passenger side of your late-model Super Duty if you’ve installed an aftermarket exhaust system. In our case, the 5-inch exhaust was very close to the upper bracketry and especially the top roll plate. Fortunately, AirLift provides a heat shield that can be installed between the air spring assembly and exhaust to keep heat off of it. However, if you’re running a 5-inch exhaust system you will have to source your own (larger) worm gear clamps to install the heat shield. On a truck equipped with the factory exhaust system, clearance would likely not have been an issue.
The tight clearance work continues when you mount the upper frame braces for the air spring assemblies. In fact, in hindsight it might’ve been easier to install the upper frame braces prior to setting the air spring assemblies in place. However, the upper frame braces did work perfectly with the truck’s existing B&W Companion fifth-wheel hitch, ultimately being anchored via AirLift’s extended length (4.5-inch long) Grade 8 (5/8-inch diameter) bolts and the corresponding flat washers and nylon lock nuts.
AirLift’s Wireless Air EZ Mount kit arrives as a pre-assembled unit that’s ready to bolt on. Unlike the LoadLifter 7500 XL system, the compressor side of the equation is universal, meaning it’s up to you to determine your mounting location and method. We were pleasantly surprised to find that AirLift included two replacement inlet filter elements with its Wireless Air EZ Mount kit.
Airlift calls it its Wireless Air with EZ Mount package for a reason. The compact system joins the air compressor with the manifold on one mounting bracket. Once we’d located a safe spot on the inboard side of the driver side frame rail, we used the supplied (and very handy) mounting template to locate the exact spots we would drill our mounting holes.
The perfect spot for us (and really the only spot we could find, for that matter) ended up being near the transfer case. We sourced our own stainless spacers to allow the compressor and manifold assembly to clear the truck’s factory fuel lines running along the frame rail.
We then began routing the airlines back to the air springs. Starting with port 1 of the manifold, the driver side air line was run, followed by a separate line being strung back to the passenger side spring. Because we elected to have a manual inflation option, the supplied tee fittings and schrader valves were also utilized.
Behind the fuel door of the truck, there is obviously a lot going on beneath the diesel and DEF filler caps, so we opted to run the manual inflation air lines into the fuel door area from above. We used a right angle drill and a stepped bit to carefully achieve the desired diameter we were after.
The end result lead to a convenient yet clean way to manually inflate our air springs, should the need ever arise. On top of that, individual lines were spanned to air up each spring separately, offering us dual-path control over inflation.
After routing our air lines, it was time to clean up the install. We did it by using the supplied zip-ties to ensure the lines were well-anchored along the chassis and away from any sources of heat (namely at least 6-inches distance from the exhaust system). We also made sure to leave 2-inches of total slack in each run of air line to allow for some movement if need be.
Per Airlift’s recommendation, we installed the air compressor’s remote mount inlet filter under the truck’s cab. It’s a location that places the filter element higher than the compressor and manifold assembly, away from heat sources, and that should remain dry at all times. Then we moved on to wiring up the compressor. Highlights there included tapping into an ignition source with constant 12-volt power when keyed on, and stringing the wiring harness toward the battery as discreetly as possible.
Now the fun part: playing with the included wireless remote control for the Wireless Air system. Once the included 15-amp fuse was installed, the compressor fired up and the air springs were automatically inflated to 5-psi. From there, the wireless remote was paired with the compressor and we were ready to test everything out. One-touch inflation and bleed-off is available at your fingertips, along with the remote control able to be used inside or outside the vehicle. We found the remote control had exceptional range at 25 to 30-feet away from the truck.
As you can see, the 44-foot, Cherokee Wolf Pack fifth-wheel toy hauler was pushing the limits of the factory suspension prior to the AirLift install. Empty, it’s a unit that tips the scales at roughly 13,000 pounds. Fully loaded, it’s north of 16,000 pounds.
Hooked up to the toy hauler with no air springs in the mix, we measured suspension sag between the top of the rear tires and the bottom of the fender well. The way the owner had been towing, that gap sat at 8-inches—and the truck definitely wasn’t sitting level.
After the install, we inflated both air springs to 55 psi and measured a gap of just over 9-inches. On top of the rear of the truck sitting an inch higher, it was now riding level from front to back.
Upon airing the springs up to 85-psi, 10-inches of gap existed between the top of our tire and the bottom of the fender well. At this pressure, some of the factory rake even came back into the picture. For this specific trailer, this much pressure won’t be required, but it’s nice to know we can level up with even more weight bearing down on the rear of the truck.
An interesting feature of the Wireless system’s remote control is its ability to show both the target inflation pressure and each spring’s individual inflation pressure in real-time. As you can see, each air spring’s pressure can be controlled separately, which comes in handy for top-heavy or uneven loads. In addition, there are three programmable inflation settings that can be configured for different trailers or loads.

SOURCES

Airlift

800.248.0892
airliftcompany.com

B&W

800.810.4918

bwtrailerhitches.com


 

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