Air suspension spring checks and repairs

Air suspension might seem scary and intimidating but the basic hardware is relatively simple. As our earlier blog explains, air leaks from worn air springs are the main causes of failure. Ignoring air leaks can damage other parts, making repair costs far higher than they could have been, had the leaks been addressed earlier.

How can I inspect the air suspension?

As air springs are produced from a flexible rubber-based material, they do not last forever. Therefore, they should be considered a consumable component, rather than one that should last for the life of the vehicle.

Being exposed to moisture and air, the flexible material perishes and these small cracks develop into splits, especially surrounding folds. Should the shock absorber/dampers leak on air struts, the resultant oil contamination degrades the material further.

To check the air springs for leaks, raise the car and support the body on axle stands. Never raise the suspension and venture beneath the vehicle, because a faulty system could lower the car onto you without warning.

With the bodywork supported and the appropriate tyre raised from the ground, select the maximum ride height, if possible. This action fills the springs with air.

Spray a soapy solution onto the air spring. Any bubbles indicate a leak, necessitating that not just the affected spring but also the opposite component on the same axle is replaced, too.

How long should air springs last?

A high-quality air spring should last between six and ten years. As the dampers are conventional, expect a similar lifespan to that of coil-sprung vehicles: 80,000 miles.

Yet, air spring longevity depends on mileage, how often the vehicle is used off-road and even the climate. In cold conditions, the air spring's rubber material hardens and becomes less compliant, increasing the risk of it tearing.

If an elderly spring has started to exhibit small cracks, a cold spell might be all that is needed for a hole to develop. Yet, hot conditions encourage the rubber to dry out faster, causing the same issue.

How do I replace an air spring?

Replacing air springs tends to be easier than conventional metal springs but this leads even professionals to make mistakes, which reduce the replacement part's life. The main steps are depressuring the system, unbolting the spring and manipulating it from the wheel arch.

It sounds easy but be careful. The most popular error involves bolting the spring assembly into place and lowering the wheels onto the ground, before reconnecting the car battery and inflating the new unit for the first time. This situation can encourage the rubber spring material to fold, increasing the bursting risk, as the bladder fills with air.

To prevent this, research the car manufacturer's specific inflation procedures. A general recommendation involves supporting the vehicle's weight with axle stands and allowing the suspension to dangle, prior to inflating the new spring.

The car can then be lowered onto its wheels, after the new spring has been inflated fully. This method ensures that the air spring is pressurised evenly, before it supports the vehicle's weight, but check if your car requires this operation to be conducted diagnostically. If it does, ensure that you have the correct equipment on hand.

Another common fitting mistake involves overtightening the air hose fittings, which strips the delicate threads. A lack of cleanliness is another issue. As you work on the system, ensure that there is no possibility of dirt entering either the compressor, or the air lines.

Therefore, take precautions, such as covering any disconnected air lines. Once the work is complete, ensure that the wheel nuts are torqued to their correct setting.

Some cars may require diagnostic calibration afterwards, especially those with Advanced Driver Assistance Systems (ADAS) which may have to be done by a garage, afterwards. This is in addition to extinguishing any suspension-related errors light/messages to ensure a correct and safe repair.

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