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Load-Leveling Systems for Towing

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Trent Riddle | Writer
Posted October 1, 2001
Photographers: Jon Thompson, Mike Duval

Fixing Your Suspension for the Long Haul

Step By Step

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  • When towing a trailer with a lot of tongue weight, and with gear in the back of your rig, you’ll likely find that your tow rig’s tail drags and its nose rides high. This is not the best chassis attitude for towing. By leveling your rig with a supplemental air suspension you’ll regain the chassis control you need.

  • AIM Industries offers a wide range of airbag styles, sizes, and mounting brackets to suit your needs. They can assemble a load-bearing and leveling kit for you that includes a compressor, two airbags with mounting brackets, an electric single-gauge system, and all hoses and hardware. This basic kit retails for $642. If you want to upgrade to a 3-gallon air-storage tank, pneumatic switch, and gauge system, the cost is $716.

  • Airbag systems for leaf-sprung trucks typically mount between the frame and the rear axle, or next to the frame over the axle, like the system seen here. If you plan to ’wheel your airbag-equipped truck, be sure to install limit straps so that you don’t damage the airbags during trail articulation.

  • This Firestone-system compressor was mounted with a small air-storage tank on a custom bracket under the truck. You can mount yours any place you find room.

  • Here you see how this airbag system bolts to a bracket mounted alongside the frame. Notice that the air line for the bag comes out of the bag’s top for maximum protection from road and trail damage.

  • Here you see a control switch and gauge panel for an airbag system. This switch panel has two switches—one for each side—and a dual-reading gauge. This indicates a system that is split for side-to-side load-leveling.

  • This is an in-coil airbag being installed on a Toyota 4Runner. By removing the shock and extending the suspension, the shop was able to install the bags without having to drop the axle and take out the spring. You may not be this lucky on every application.

  • This is an example of Air Lift’s Super Duty 5700 series airbag system. The units are suited for all uses from a 1/2-ton truck up to a Class C motorhome. They are rated to handle loads from 3,000 to 5,000 pounds. MSRP averages about $309, depending on the system.

  • Look closely and you’ll see the bag spacer and protection ring inside the coil and on top of the airbag. This piece is vital and should not be forgotten. Leave this out and at best, your system will work poorly, and for a short time. At worst, it won’t work at all.

  • This is an example of Air Ride’s 3,000-pound side-frame airbag system. MSRP averages about $275 depending on the system.

  • This is the top-of-the-line ARC2000 2-way solenoid-control system, air compressor, and air tank from Air Ride. It retails for $699. If this is more than you need for your airbag system, the company also offers a basic compressor and control-panel kit for $225.

  • Firestone may be the best-known airbag manufacturer in the market. Pictured here is one of Firestone’s Ride-Rite heavy-duty systems in place. These typically are rated at 3,000 to 5,000 pounds and are suitable for applications of all sizes. MSRP averages about $295 depending on the system.

  • Firestone also markets in-coil airbag systems under the Coil-Rite name. These systems are good for leveling the back of coil-sprung trucks and SUVs. They also work well to raise the front ends of snow-plow trucks. MSRP averages about $100 depending on the system.

Have you ever loaded the back of your pickup or SUV with all your gear and then noticed that the rear end has hunkered down? Maybe you then tried to tow a trailer with your trail rig on it. The next thing you knew, the back end of your tow rig was almost dragging.

If you haven’t yet experienced this woe, you still might. And if you have, then you know the feeling of fear and dread that riding nose-high instills in a driver. The dread is there because as the back end of a truck is pushed down, and the front is forced up, things get hard to control. Steering control is reduced and the braking ability is adversely affected. Further, you’ll find that the trailer is unstable. If you tow a lot, as we do, you know that sometimes you can move your trail rig around on the trailer to help to offset this problem. But only sometimes. Usually the trouble isn’t too much tongue weight, but rather too much trailer weight overall.

For things to work properly when towing a trailer, you should load your trailer so that the tongue weight is 10 to 15 percent of the total weight. This means that if your trailer and trail-rig combination weighs 8,000 pounds, for instance, you should have between 800 to 1,200 pounds of tongue weight. Now with an average of 1,000 pounds pushing down on the very back of your truck, you’re sure to get some settling of the suspension. When you add the weight of gear to your rig too, well, you see the problem. The solution is to stiffen the rear spring rate. Yet you don’t want this stiff suspension when you’re driving around town unloaded.

There are two ways to overcome the problem of a suspension that is occasionally too soft when you load your truck or SUV for the long haul. One is to install helper leafs that only come into play when the suspension is loaded. When you choose this solution, an extra spring and stop are added to the rear suspension and when the load compresses the stock springs far enough, you begin to use the helper leaves. The trouble is, your truck was built to handle best when it sits level. By its very nature, this solution guarantees you’ll ride a little nose-high no matter what. A better option is an airbag load-leveler system.

Airbag systems can be mounted to almost any truck and have several advantages over other methods of load-leveling. First of all, you’ll be riding on a cushion of air just like those city buses and large moving vans do. This means a smoother ride than any spring system can offer when loaded. In addition, you can usually fill the airbags enough to bring your truck back to a level pre-loaded height for the best handling. Further, if you are forced to load the bed of your truck unevenly, you can level the load side-to-side if you need to (for this option you need to have a split-air system).

Airbag load-leveling systems are available in a wide range of configurations and from several sources. However, when you get down to the basics, you really have two types of airbags. There’s the in-coil bag, and the outside-the-coil bag. In-coil airbags are just what they sound like—pressure bags that go inside the coil springs of your rig’s rear suspension. Of course, if you have leaf springs you can use the out-of-coil bags that mount with brackets either to the side of the frame or between the axle and the frame. Both serve the same function and you’ll be happy with whichever system your rig’s rear-suspension system requires. Installation is simple in most cases and usually can be done in less than a day.

As a plus, you’ll get an air compressor and a storage tank for your truck that can be used to fill tires when, for instance, you have to get on the highway after towing down a sand wash. If you want to, you can even install a compressor to match the one on your trail rig so you’ll have a spare in emergencies. Oh, you’re looking for an air system for your trail rig? We’ve got you covered. Just check “Give Me Air,” (June ’01) for information on 12-volt air sources for your trail rig.


Indianapolis, IN 46260
AIM Industries