With a "leg up" on other companies, GM used its experience with commercial busses' air suspension to introduce systems for its car lines, beginning with the 1958 model year. Air bags at each wheel replaced the standard coil springs, and had sensors to keep the car level under load and in turns. It was too slow to react in sudden maneuvers, however.
Period reviews rated the air suspension somewhat superior in ride quality, but not dramatically. Some reliability issues plagued these systems, as well. Thus, as an option, air suspension was short lived in that era.
The air suspension designs from Land Rover, SsangYong and some Audi, VW, and Lexus models, feature height adjustable suspension controlled by the driver, suitable for clearing rough terrain. The Lincoln Continental and Mark VIII also featured an air suspension system in which the driver could choose how sporty or comfortable they wanted the suspension to feel. These suspension settings were also linked to the memory seat system, meaning that the car would automatically adjust the suspension to the individual driver. The control system in the Mark VIII also lowered the suspension by about 25 mm (1 inch) at speeds exceeding about 100 km/h (60 mph) for improved aerodynamic performance. Unfortunately, however, these systems turned out to be unreliable and in many cases ended up being retrofitted by aftermarket replacements or conventional steel coil springs.
In addition to passenger cars, air suspension is broadly used on semi trailers and buses, which are both transportation sectors that helped pioneer the use and design of air suspension.
The installation and configuration of these systems varies for different makes and models but the underlying principle remains the same. The metal spring (coil or leaf) is removed, and an air bag, also referred to as an air spring, is inserted or fabricated to fit in the place of the factory spring. When air pressure is supplied to the air bag, the suspension can be adjusted either up or down (lifted or lowered).
For vehicles with leaf spring suspension such as pickup trucks, the leaf spring is sometimes eliminated and replaced with a multiple-bar linkage. These bars are typically in a trailing arm configuration and the air spring may be situated vertically between a link bar or the axle housing and a point on the vehicle's frame. In other cases, the air bag is situated on the opposite side of the axle from the main link bars on an additional cantilever member. If the main linkage bars are oriented parallel to the longitudinal (driving) axis of the car, the axle housing may be constrained laterally with either a Panhard bar or Watt's linkage. In some cases, two of the link bars may be combined into a triangular shape which effectively constrains the vehicles axle laterally.
Often, owners may desire to lower their vehicle to such an extent that they must cut away portions of the frame for more clearance. A reinforcement member commonly referred to as a C-notch is then bolted or welded to the vehicle frame in order to maintain structural integrity. Specifically on pickup trucks, this process is termed "notching" because a portion (notch) of the cargo bed may also be removed, along with the wheel wells, to provide maximum axle clearance. For some, it is desirable to have the vehicle so low that the frame rests on the ground when the air bags are fully deflated.
Air bag or air strut failure is usually caused by dry rot, due to old age, or moisture within the air system that damages them from the inside.
Compressor failure is primarily due to leaking air springs or air struts. The compressor will burn out trying to maintain the correct air pressure in a leaking air system. Compressor burnout may also be caused by moisture from within the air system coming into contact with its electronic parts.
In Dryer failure the dryer, which functions to remove moisture from the air system, eventually becomes saturated and unable to perform that function. This causes moisture to build up in the system and can result in damaged air springs and/or a burned out compressor.