Air suspension or coilovers: which is better, and why does air suspension fail?

How air suspension works

Each corner has a rubber air spring (bellows), often combined with an adaptive damper. A compressor fills the springs through a valve block; height sensors tell the control unit where each corner is; an air dryer removes moisture from the intake air; some systems use a reservoir for faster lifting.

How it fails

The rubber bellows age with heat, UV and flexing, and crack at the folds. A small leak makes the compressor run more often and for longer. The compressor overheats, its piston seal wears, and it eventually fails — or its relay burns out. Moisture passing a saturated dryer causes corrosion in valves and lines. Valve block leaks, damaged lines and faulty height sensors complete the list.

The first sign is usually a corner sitting low after the car has been parked, a slow rise at start-up, or a compressor running longer than before. Replacing the compressor without fixing the leak means a second compressor soon after.

Coilovers

A coilover is a steel spring around a damper, with adjustable spring seat height and, on most kits, adjustable damping (rebound only, or rebound and compression). Fixed spring rates make the car predictable on track, and there is no compressor or control unit to fail. The trade-offs: firmer ride on bad roads, no load levelling, fixed ride height in daily use, and periodic damper servicing on performance units.

Converting from air to coilovers

Possible on many cars, but the control unit expects air components: warning lights, disabled functions or coding requirements follow. Done properly, it means the right kit, coding or modules where needed, and a full alignment afterwards.

General comparison; kits and systems vary widely.