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Adding Airlift to Your Suspension

If your tow vehicle is sagging in the stern, it may be time to pump it up.

A level connection between your trailer and tow vehicle, which improves stability, is easier to achieve if you have adjustable suspension.

When most of us talk about our rear ends dragging, we seldom mean the one on our trucks. But gravity gets to our vehicles, too, eventually. Signs that your vehicle may need additional support in the suspension department when its towing your boat include a visibly sagging rear end, headlight beams that are directed higher than normal, nose-diving by the vehicle when you brake or porpoising while underway, suspension that feels like it bottoms out when the vehicle passes over bumps in the road, and a ride that's generally rough, uneven, or simply uncomfortable. Even abnormal tire wear can be a sign of an overworked suspension.

TIP: Beefed up suspension doesn't mean you can exceed the maximum tongue weight. Keep to the limit of your hitch, or you risk a fishtailing trailer — or worse.

Trailerable-boat owners have several options for adding aftermarket load support to tow vehicles. One of these might help if your tow vehicle is older and the suspension system no longer offers the spring rate that it did when it was new, if the weight of the boat-and-trailer rig you tow is pushing the maximum for your vehicle's rating, or if you're limited in the ability to achieve the right tongue weight from your trailer. If you tow loads of varying weights, or you want the most fuel-efficient, comfortable, and custom towing ride possible, you may also consider upgrading the suspension.

Popular aftermarket load supports include additional leaf springs; larger bump stops, or "jounce bumpers," than the ones originally installed; and air-suspension systems. Your vehicle and its suspension system may limit your options. For example, air-suspension systems are available only for tow vehicles equipped with leaf or coil springs. Air suspension systems use rubber bladders that are fitted inside the coil springs and filled with compressed air to support and cushion the load carried by the factory suspension. Increasing or decreasing the PSI with an onboard or stand-alone compressor adjusts the amount of support.

Fortunately, most popular boat-towing vehicles are candidates for air-suspension systems, which, due to their easy adjustability — even on the fly, with some models — are a good choice for boaters who want to customize their towing systems. Air-suspension systems are available for everything from half-ton pickups and SUVs to one-ton trucks. Just remember that no aftermarket load-support system increases a vehicle’s tow rating or capacity, and it’s extremely important to remain within those limits specified by the manufacturer.

After some research on the various air-suspension systems available for DIY installation, I chose an Air Lift 1000, a model designed by the Air Lift Company, located in Lansing, Michigan, for use in such vehicles as our 2006 Chevy Tahoe. The SUV has more than 100,000 miles on the odometer and a suspension I suspected could use a boost when towing my 3,660-pound project boat-and-trailer rig. I selected an onboard compressor controlled by a WirelessONE key fob so I could adjust the system’s PSI, and therefore the ride, while driving.

According to Jeremy Hart of Air Lift's tech-support team, the Air Lift 1000 and WirelessONE kits are good DIY projects for boaters who are handy with tools and have the means to support the vehicle — to take the weight off the suspension and allow access to same — while installing the system over the two to three hours he estimates it takes to complete the project. To watch and photograph what was involved in an installation, I engaged the help of my local Air Lift dealer, Funtrail Vehicle Accessories of Columbus, Ohio.

1. The Air Lift kit. Tools needed include a drill/driver, wire and hose cutters, wire stripper/crimper, screwdriver, pliers, test light, heat-shrink gun, soapy water, and Windex. The first step is to raise the vehicle high enough — and safely suspend it there — to take the weight off the springs and allow you room to work under the vehicle.

2. Once you have access to the rear springs, compress and fold each rubber bladder into a hotdog-bun shape to force it between the coils. Once these are inserted, allow them to reform to their originalcylindrical shape. Our tech suggested spraying the rubber bladders with Windex to act as a lubricant when squeezing them between the coils.

3. Select a location to mount the manifold and compressor on the frame or a cross member. Since the vehicle will be used for launching and loading trailered boats and the rear may be in closer contact with the water, it's important to choose mounting locations farther forward on the chassis. I chose to mount the compressor on the side of the chassis under the passenger door. According to Jeremy Hart, one of Air Lift's tech-support team, the components are designed to get wet but not to be submerged for very long.


4. Protect the power wire with wire loom.

5. As a backup for filling and releasing air from the system, I installed a manual valve on the rear bumper that permits the use of a stand-alone compressor — or even a bicycle pump (with a lot of work!)


6. Run the compressor wiring, which has an in-line 15-amp fuse, to the vehicle's main fuse panel under the hood as the power source.

7. Install the in-line 15-amp fuse in the power line from the compressor to the fuse panel using heat-shrink connectors.


8. Connect the power wire to the tap fuse in the panel. Turn on the ignition to activate the system. Fill the bladders, then look for leaks at all connections using soapy water, which will bubble to reveal leaks.

9. Drop the vehicle to the ground and test for air pressure and lift again, then hook up the trailer and experiment by adding and releasing air up to the maximum PSI recommended.


Dan Armitage

Contributing Editor, BoatUS Magazine

A full-time travel and outdoors writer based in Ohio, Dan is in his 20th season hosting the popular syndicated radio show Buckeye Sportsman. He gets around on a pontoon boat and an Aquasport center-console, which he uses for all his DIY editorial projects and fishing features. A USCG Captain (Master 50-ton), he’s a popular speaker at boat and sport shows.