Under Pressure: Air Lift’s Smart Air II Automatic Load Leveler


Since 1949, Air Lift has been innovating new ways to expand the usefulness of automobiles around the world. The first Air Lift product was a rubber air spring inserted into a car’s factory coil spring, significantly increasing the amount of weight the vehicle could haul without having to change the entire rear suspension or sacrifice the vehicle’s ride and performance. After the company got their first patent in 1950, the game was on. It’s been heavily involved with the load support product scene since, especially in no-drill applications.


Air Lift has designed a bump stop into its air bags.

One of the very few drawbacks of air-based load support products is the need for the consumer to know how to properly operate the system and what pressure to fill the system to, depending on the additional weight added to the vehicle. This can be time-consuming. Figuring out how many extra pounds have been loaded, sorting out how much pressure needs to be added to the air bags and then filling them – Not an overly complicated process, but it can take away from work or fun all the same.

Air Lift developed a system for commercial vehicles, ambulances, handicap vans and the like that used height sensors and specially designed software to keep the vehicle level and safe to operate with varying weight loads. After years of use in these applications, Air Lift brought the Smart Air II system to market for consumer use.

SmartAir II is really simple to use, because you don’t have to do anything to use it. It just automatically keeps your vehicle level, no matter what. – Ryan Feyer, Air Lift Marketing Manager

The Smart Air II system utilizes unique non-contact magnetic height sensors to automatically level the vehicle. That means there are no levers, sensor arms, or any other linkages providing input to the sensors that can potentially become a target or road debris or physical failures.

The information coming from the electronic height sensors goes to a small onboard computer system that then crunches the data and automatically changes the pressure in the air springs accordingly. More weight added, more air added. Weight removed, air removed. All on its own.

Air Lift’s installation instructions go deeper into how the system works – “The electronic height sensor (EHS) is mounted to the vehicle frame and the magnet and bracket is mounted to the axle or leaf spring. When a load is added to the vehicle, the magnet rises above the EHS centerline (as the suspension is compressed). If the magnet maintains this position for a minimum of 15-20 seconds, the EHS will turn on the compressor, adding air to the air bags. Air is added until the magnet is re-centered, restoring the vehicle to its pre-programmed ride height.”

Air Lift uses weather resistant and OEM quality materials for their products to ensure a long lasting and useful install.

Air Lift uses weather-resistant and OEM-quality materials for their products to ensure a long lasting and useful install.

Additionally, the Smart Air II system is built using weather-resistant OEM-grade materials. High-quality materials equate to strong and reliable use for extended lengths of time. The system is responsive and accurate within 1/16th of an inch, comes with a pre-assembled wiring harness and utilizes a 100psi air compressor that pumps out 0.92 CFM on a 15-percent duty cycle.

We paired up the Smart Air II system (PN 25491) with Air Lift’s LoadLifter 5000 Ultimate (PN 88396) to be installed on a 2011 Ford F-250 Super Duty. The LoadLifter 5000 Ultimate kit is designed to increase the weight-bearing capacity of a vehicle by up to 5,000 pounds. Being a no-drill application, the LoadLifter 5000 kit can be installed in less than two hours. The Ultimate kit includes Air Lift’s exclusive internal jounce bumper (bump stop).

To get some insight on what drove Air Lift to build an air bag with a bump stop built into it, we had a chat with Ryan Feyer, Air Lift’s Marketing Manager. “We decided to develop the LoadLifter 5000 Ultimate product line because we found that in many cases you needed to remove your factory jounce bumper to install air springs.” Feyer explained further that “[t]his leaves the air spring itself as the suspension limiter when fully compressed. We put a jounce bumper inside of the air spring to ensure that, in the case of a bottom-out situation, there is no harsh jarring or metal-on-metal contact.”

LoadLifter 5000 Ultimate System Install


To test out the goodies from Air Lift, we snagged a 2011 Ford F-250 Super Duty and hoisted it up. We installed Air Lift’s LoadLifter 5000 Ultimate and Smart Air II Dual Path system. We started with the air bag system.

Air Lift prides itself on an easy installation and is constantly reevaluating its products, looking for ways to improve. Due to the positioning of the Ford rear OEM components, the original design required extra pieces. Air Lift has since redesigned the system to make install that much easier.


The factory Ford F-250 rear suspension can handle a fair amount of weight. Under those loads, however, the back end of the truck can sag. Bringing the back end of the truck down will negatively affect the vehicle’s driving characteristics. That isn’t good when unloaded, let alone when you’ve got some serious weight behind the vehicle.

Always lay out your parts before you start. This will help make sure you have all the necessary parts and tools to complete the installation. We started by assembling the air bags and brackets.

Follow the Air Lift instructions closely to properly assemble the air bag and bracket system.

An installation such as this on an F-250 require the removal of the factory bump stop. This is where the ultimate air bags come into play. The internal jounce bumper can now effectively take the place of the OEM bump stop in the suspension’s movement.

The factory bumpstop is a simple removal, a single bolt on each unit will release it from the frame.

The factory bump stop is a simple removal. A single bolt on each unit will release it from the frame.

The assembly can now fit into the vehicle. The upper brackets tie into existing holes in the Ford frame, saving the time and anguish of having to drill new holes. Every Super Duty comes with an OEM lift block between the leaf springs and the differential housing tube. Taking advantage of this, Air Lift built a lower bracket that keys off of the top of the bump stop pad that is cast into the lift block.

air lift

The lower bracket positions itself over the bump stop pad built into the lift block. The bracket then gets secured to the differential housing as well as the block and u-bolt assembly. This avoids both vertical and horizontal movement.

Smart Air II Dual Path Automatic Load Leveler


The Smart Air II system is neatly packaged to make the install quick and painless. The system is comprised of five parts: the compressor, the solenoid, the sensor, the magnet, and the wiring that connects it all.

The compressor assembly gets mounted to the inside of the frame rail using self-tapping bolts. The air switch solenoid gets mounted the same way. An air hose runs from the compressor to the solenoid, and then another heads off to one of the air bags.

In the Dual Path kit, each side of the vehicle gets its own compressor assembly and solenoid. This allows for each side to work independently from the other, making uneven loads a problem of the past.

air lift

A bracket is added to the top of the leaf spring assembly to support the magnet. After the magnet is positioned, the sensor can be aligned and installed.

The non-contact height sensor reads the positioning of the magnet. Based on a pre-calibrated setup, the system then knows if the vehicle has been weighted down or not.

Just about done. With the magnets and sensors installed, all that is left if running the wires.

Just about done. With the magnets and sensors installed, all that is left if running the wires.

Because the system is a set-and-forget setup, there is no need to run any wires into the cab. No holes need to be put into the firewall or anywhere in the vehicle for a gauge or switches. The pre-built and pre-terminated wiring harness gets plugged into the sensors, solenoids, and compressors, then runs to the front of the vehicle, where it enters the engine compartment from below.

air lift

Connect positive and negative and the kit is ready to go.

air lift

The LoadLifter system does include a pair of manual air chucks as a precautionary backup, though you won’t need them. On this install, we ran them through to the rear bumper and will use them to hold the license plate on, effectively masking that they are there at all.

Air Lift’s Smart Air II Dual Path Load Leveling System is a no-brainer in the truest sense of the phrase. This is an easy install that you don’t ever have to mess with. Just let it do its thing and you’ll be driving down the road in safety and style. For more information on the Smart Air II and LoadLifter 5000 kits, head over to the Air Lift website.

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About the author

Jake Headlee

Jake's passion started at a young age wrenching on cars with his Dad. Obtaining that glorious driver's license sparked his obsession with grease and horsepower, and the rest is history. Soon, he was a general mechanic and suspension specialist, and currently designs and modifies products for the off-road industry. Jake enjoys rock crawling, desert racing and trail running, and writing in his spare time.
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