The most common source for...
The most common source for air-spring leaks is at the fittings. A little Teflon tape or thread sealer on the fitting threads can help ensure an air-tight system.
DO Use DOT Air Lines and Fittings
Air lines and fittings approved by the Department of Transportation (DOT) are rated for extreme vibration, abrasion, and temperature. This is the same reinforced nylon line you find under big rigs to run their air brakes. Normal industrial polyurethane lines are NOT intended for such harsh environments. DOT air lines will always have a DOT certification number stamped on it. You can identify DOT fittings by looking for an attached inner sleeve that prevents the line from deforming inside the fitting.
DON'T Plumb Air Springs in Pairs
It may seem faster and easier to "double up" and supply two springs with one air line, but such convenience will compromise performance. Running individual air lines to each air spring prevents air transfer from side to side when cornering. This will help cornering performance significantly, and will also allow you to adjust the air pressure to level the car.
DO Pay Attention to Tire and Ground Clearance
The air-spring ride height must be synchronized with the intended ride height of the vehicle. Additionally, it's imperative that you check ground clearance and tire clearance at ride height, full extension, and full compression to be certain there is no interference between suspension components.
DON'T Expect an Air Spring to Cure Other Suspension Ailments
Air springs can offer many assets to your rod's or custom's ride and handling, but they can't perform miracles. It's important that all other suspension components-bushings, ball joints, shocks, and steering parts-are in good shape, so the air springs can perform to their potential. You can't expect air springs to rectify ride and handing problems caused by a suspension that is damaged, improperly installed, or poorly set up.
DO Check the Angle and Travel of the Driveshaft and Ball Joints
Every part of your suspension has physical limitations that can be affected by significant ride height alterations. Ball joints can bind if they are pushed beyond normal operating angles, so you need to find-and stay within-their limits when setting up your air springs. Likewise, lowering the rearend will affect the driveshaft angle, which may need to be adjusted to prevent driveline shake.
This is what can happen when...
This is what can happen when there are no extension stops in place and a rear axle is allowed to "hang" on the air springs. The end popped off this sleeve-style spring, forcing the owner to replace it.
DON'T Lay the Car on the Ground
This will probably always be the most ignored rule of air springs. To ensure the safety of you, your passengers, and your car, you should maintain at least one inch of ground clearance when the air springs are fully deflated. Also, make sure you have proper tire clearance when the springs are deflated. According to Voelkel, Firestone double-convoluted air springs act as their own bumpstops because they maintain rubber-to-rubber contact when fully deflated, but other air-spring brands and styles may need external bumpstops to prevent damage when fully deflated. In addition, these other styles of air springs need extension stops to prevent them from overextension. Usually the shock absorber will accomplish this task.