Installing air bags on customs and hot rods

Custom Bay air bags suspension modification modifying suspensions 1961 Olds Bear Metal Kustoms specialty parts vehicle accessories Suspension designs and modifications have come a long way since the early days of hot rodding. Back in the day, a quick but crude way to lower a car for speed and style was to cut a coil or two out of the springs with a blowtorch. While it dropped the chassis into the weeds, as the old saying goes, this method also minimized the range of spring travel, so both handling and ride quality suffered as a result. Not only that, getting over a speed bump or a drainage gully usually scraped the frame.

Installing air bags is a safe and practical approach, as you can lower the ride at the push of a button and raise it for daily driving. A number of companies offer air suspension systems, but we'll focus on one from Accuair Suspension installed on a 1961 Olds at Bear Metal Kustoms.

Air bags appeared on racetracks in the 1950s until the early '70s, because they improved launch, equalized thrust and kept both rear wheels on the ground. A number of pioneering legends of NASCAR found success when their racecars were outfitted with air suspension.

The technology has evolved significantly during the last 50 years, providing load support for heavy-duty applications, as well as lowering kits for sport trucks and street rods. Air is basically preferable as a suspension component over steel.

When a given volume of gas confined within a container is compressed, it produces a reaction force. In the case of air springs, the gas is air and the container is a sealed fabric-reinforced rubber bellows or sleeve. Similar to a ball inflated with air, the load an air spring can carry depends on its diameter, and thus the area of the column of air supported and the pressure of air inside it.

Increasing the load an air spring can carry is accomplished by increasing the pressure inside the air spring, increasing the diameter of the air spring or both. Clearly, the ability to change the load carrying capacity simply by changing the air pressure rather than changing out the air spring is a major advantage that air springs have over steel springs.

Putting an air spring suspension on a chassis not only can level the vehicle both transversely and from front to rear, but also can stabilize the vehicle and maximize the vehicle's load-carrying capacity. This versatility is what makes an air bag system so appealing. An air suspension is tunable for a variety of load characteristics and ride qualities. It lets you optimize the load capacity and spring rate for nearly any weight vehicle, so you can reconfigure your suspension when the load changes.

Another advantage is that you don't have to know the final weight of the vehicle, because you can tune the suspension once the vehicle is loaded. However, air springs do not increase the total load-carrying capacity of the vehicle, so you should never exceed the vehicle's recommended gross vehicle weight rating (GVWR).

Air bags typically mount between the frame and the suspension. How long does it take to install a system? Assuming you know your way around a suspension and this isn't the first time you've had a wrench in your hand, it probably will take a couple of days or so, depending on how much fabrication work is involved. Jason Pall of Bear Metal Kustoms, who is a seasoned rod and custom builder, welded up some mounting plates and cups to fit on a '61 Olds using Accuair's raw materials.

For an independent shop that plans on installing air suspension systems, having a hoist, jackstands and air tools will make the job go faster. You'll also need a drill, tappers, a ratchet set and wire crimpers.

"Installing an Accuair is pretty straightforward," Pall points out. "The biggest thing is to plan your project ahead of time. Make sure it's in your skill set. And three more things: clearance, clearance, clearance. You don't want anything to rub against the bags, lines or wiring."

Once done, your customers will be able to make their rods nice and low for show, but still roll down the road in comfort. Their vehicles will handle better and ride a lot smoother, and also have the right stance for taking home some trophies.

Steve Temple is a freelance technical writer and photographer with more than 25 years' experience. He has been director of sales and marketing for Shelby American and online editor for magazines such as Hot Rod, Car Craft and Rod & Custom.