Basics of Air Suspension
It’s tough to get that “perfect” ride height with the vast selection of shocks, springs, coil-overs, spacers, leveling kits and everything else flooding the market these days. One of the options is to utilize an air suspension system. Air ride systems offer the ultimate resolution to having a vehicle with no compromises to the aggressive looks of your vehicle at the expensive of drivability. Drive down the road with the oil pan and undercarriage clearance of a modern OEM car, and park it aired down to a height that is typically reserved for car culture artists to imagine. There are a few primary necessities involved with an air system, as to be expected. You’ll be in need of a compressor, a tank, air lines and fittings, and of course, air bags.
This article is not intended to be an instruction manual for the installation of an air ride system, just an overview of what is involved in setting one up. As that old saying goes, there are a lot of ways to skin a cat, so we picked one that was familiar and seemed like it could be tackled in a weekend.
When it comes to the rear of your project, one of the options available is a “bag over axle” system, where your airbag is mounted to a plate on the top of your axle. You can also build the system into an existing triangulated 3-link or a traditional 4-link setup. Depending on your suspension, a panhard bar may be needed to keep the rear end centered in the frame and eliminate “walking” from one side to the other. Existing coil over systems can be converted easily making use of Shockwave air springs. These shocks with an air bag surrounding them are direct replacements and bolt back into the same mounting hardware as many common coil over shocks do.
In the front, if you have an IFS-style setup you can relocate your shock mount to the side or back and essentially replace the spring with the air bag. There may be quite a bit of fabrication involved with this step, so take stock of your abilities before you tackle it. If you have a full shop and plenty of time and tools, have at it. If you’re like me, however, and work on your project when you can, in the back yard, you might consider having a shop do the install. Typically, the main work is welding a plate across the open spring pocket on the lower control arm giving the bottom of the air bag a flat mounting surface. The upper plate of the air spring is generally attached to an adaptor cup that bolts into the upper spring pocket. It is quite simple to fabricate consisting of round steel tube the same outside diameter of the springs you are removing. A round disc is welded to close one end of the tube and attaches to the top of the air spring. This cup tucks up into the cavity in the frame that formerly housed the top of the coil spring. It acts as a spacer for the air bag, keeping it away from possible rubbing points and allowing the vehicle to maintain a stock ride height when aired up. Typically extended air bags are still 3-5” shorter overall than in comparison to a compressed coil spring, so this spacer is used to select the range of ride heights available.
Mounting the compressors and running the air lines is a matter of personal preference. Compressors come in both stand-alone electric units and also engine mounted belt-driven styles. Each has its advantages and its disadvantages. While less expensive, the electric units are louder than the belt driven units, and while the engine driven units offer a constant supply of air, they are considerably more costly and complex. Tanks are the same way; you can get a large tank and display it, or a smaller 3 gallon, 4 gallon, or 5 gallon tanks and tuck it away. Speedway offers several designs of air tanks, one for any application. The larger the volume of the tank the less the compressors will need to refill them, the smaller the easier it is to hide them away.
The control of the air ride system is through a handheld controller and electronic solenoid valves. The controller selects the opening and closing of the valve; allowing air pressure to either enter or exit the air spring. Speedway offers several designs of controllers, from simple to complex. The Accuair system controls the solenoids through a computer that can repeat preset heights and consistently put the vehicle to the same ride height again and again. This system monitors how high the vehicle is with data recording sensors. This means you can set the car at your predetermined cruise height, pile 5 friends in the car and the air system will adjust, adding air pressure, to keep the car in the same position without ever touching a button. Air suspension has come a long way since its inception and this Accuair system offers the user interface and feel of a top of the line modern luxury car, rather than the early systems that frequently broke down or moved abruptly like a carnival ride. This was just one application, keep in mind with time and effort and ingenuity you can do anything to your project, we just want to be there to help.