An air suspension upgrade can improve your car’s comfort.
Whether it’s speed bumps in a residential cul-de-sac, low curbs on driveways, or even potholes or unintended bumps on the road, it’s sad to say that roads in the UK don’t really favor heavy-load-bearing or high-performance sports vehicles. There have surely been times when you’ve wanted to raise your truck’s or car’s suspension to help it clear an obstacle more easily. Similarly, sometimes when there’s nothing in the back of your van, you’re sitting quite high and you can feel yourself going much slower than usual. While normal suspension systems that revolve around coils and springs are comfortable and maintain good vehicle handling, they don’t offer you the possibility to raise or lower your vehicle. Enter air suspension.
Air suspension, or air-ride, has been around for a long time, and replacement kits first appeared for sale to be fitted to cars as early as 1920. In addition to providing driver comfort, it was used from the start as self-leveling suspension for heavy loads. People even used it to help smuggle illegal moonshine! That’s why, even today, many new trucks and trailers are equipped with air suspension systems, and there is a multitude of replacement kits that can be fitted later.
Air Lift is one of the best-known companies for replacement air suspension, and it has been around since 1949. Although we tend to associate air-ride as being more focused on comfort than performance, it was extremely popular in dragster and NASCAR racing in the 50s and 60s.
So, what is this air suspension, why do people want it, and what are the advantages and disadvantages of using air suspension?
WHAT IS AIR SUSPENSION AND HOW DOES AIR SUSPENSION WORK?
Conventional shock and spring suspension systems that feature steel components provide a vehicle with great handling and fantastic performance at all levels. Air suspension, however, replaces these components with robust rubber airbags that can be inflated using an onboard or external air compressor. This allows the vehicle to raise itself or lower itself depending on the inflation level of the airbag and can make a car much more comfortable to drive or give it a better appearance. Does air suspension affect performance? Yes – but not necessarily in a bad way. Modern kits also feature elements such as adjustable camber mounts and adjustable damping, meaning you can have the best of both worlds.
It’s important to note that there are two different types of air suspension: “semi” air suspension and “full” air suspension.
“Semi-air suspension” supports the existing suspension of a car. This is often found on heavy goods vehicles or trucks. An air spring is installed between the chassis and the rear axle, which increases the vehicle’s ride height and generates greater spring travel. In this way, semi-air suspension helps increase the level of comfort and stability when you are traveling in your vehicle.
If you have suspension issues, full air suspension could be a fully automatic and adjustable solution. The conventional suspension system is completely replaced by a full air suspension system that filters out road surface irregularities, making the ride much more comfortable.
So, ultimately, the only major difference between conventional and air suspension systems is that instead of the car sitting on a coil spring, it is sitting on a rubber bellows of compressed air. As the bags are not pre-inflated, they are powered by an air tank and an electric air compressor, with the car needing to be lifted and lowered simply by inflating and deflating the bag.
WHAT ARE THE KEY COMPONENTS OF AN AIR SUSPENSION SYSTEM?
AIR SPRINGS (BAGS)
These are solid rubber bases that replace the coil spring of a conventional setup. They come in two main styles: the coilover configuration or the conventional style. In the coilover configuration, the bag has a hole in the middle allowing the shock absorber to pass through it. In the conventional style, the bag is completely independent of the shock absorber.
Modern airbags are not like a balloon filled with air that we might imagine. They are solid and durable and are designed in such a way that they only expand and contract from top to bottom. At full inflation, they can have an air pressure of 100 psi.
SHOCK ABSORBER
If you have a suspension design where the spring is mounted separately from the shock absorber, the same shock absorber that you would have used with your conventional coil spring can be used. Fortunately these days, with the rise in popularity of airbags in the tuning scene, there are now coilover-style kits for a wide range of cars, offering a matched shock and airbag combo. These kits not only simplify installation, but they improve handling and ride. Many of them feature shock absorbers with height-adjustable platforms for the bags, adjustable damping, and even adjustable camber top mounts.
COMPRESSOR
Air doesn’t just magically enter the airbags. That’s what the compressor does. All air suspension kits require at least one compressor, and you’ll generally find that the one supplied is quite small and compact; they often fit neatly in the car’s trunk. They often run on a 12-volt power supply and therefore won’t drain your battery. The big issue is, however, that they are often very noisy.
AIR TANK
That noise from the compressor is what makes the air tank necessary. You could have air-ride without it, but the pump would have to run far too often and it would take too long to lift the car unless the pump was gigantic. An air tank is used as the main supply for the airbags, and the air compressor simply serves to keep the tank above the minimum pressure. Depending on the size, air tanks allow the suspension to be lifted at an acceptable speed without the compressor needing to kick in. This also needs to be stored in the trunk of many cars. You just have to decide what matters most to you; more trunk space or a larger tank.
ADVANTAGES
IMPROVED FUEL ECONOMY
The higher your suspension is, the higher the wind resistance of the truck and trailer, meaning your fuel economy is going to be worse.
Advanced air suspension systems can adjust the ride height based on the load weight and the type of journey you are making. For long highway trips with light loads that don’t compress the suspension as much as heavy loads, the suspension can be set lower to maximize your fuel economy. For heavy loads, the suspension can be made as firm as needed and the vehicle remains lower to the ground due to the heavy load. In both situations, the vehicle remains low and allows you to save fuel. In a conventional suspension system, if the load was light, the vehicle’s suspension, which is designed for heavy loads, would remain stiff and your fuel economy would be much worse due to the resistance.
MORE ENVIRONMENTALLY FRIENDLY THANKS TO REDUCED CO2 EMISSIONS
Due to this decrease in fuel consumption and the smooth ride, it automatically means you use less fuel, journeys are faster and shorter, and consequently, it’s much better for the environment. That’s something we can all be happy about!
REDUCED VIBRATION
Better for your cargo and better for your back on those long journeys, air-ride reduces vibrations from the truck or car. Back pain isn’t just something that comes with age; Long-distance heavy goods vehicle drivers can experience it if they are in a seated position for a long time. Vibrations also cause fatigue and discomfort, meaning a happier, fresher, and ultimately safer driver.
Similarly, the cargo carried by the truck is less likely to be damaged or shift in the back of the van or truck as well (although load packaging and restraint methods these days are very good anyway).
Alongside this, a trailer can be used for more types of loads when the suspension setup is flexible. Fragile loads such as glass are less likely to be damaged, and loads with difficult weight distribution can be leveled.
IMPROVED TYRE WEAR AND HANDLING
Less vibration and better load distribution through leveling improve tire wear. Some air suspensions can even lift unused axles, thereby prolonging the life of those tires.
Suspension is also a major factor in how a vehicle behaves. Better suspension could mean less likelihood of a rollover event. If the vehicle is higher off the ground, it is much more difficult to handle, and this can be a problem for vans or trucks with a rigid suspension system when they are not carrying a load.
EASY INSTALLATION
The advantage of these systems is that they are very easy to install. 5 years ago, it might have been a bit different, but nowadays, there are various direct replacement kits for a large number of popular cars. While fitting a full air suspension system to a car remains a job for professionals, for most of us, fitting a semi-air suspension is no more difficult than fitting a set of coilovers and shouldn’t take more than a day to do. These “plug-and-play” semi-air suspension kits are also relatively inexpensive. Where to install the air suspension isn’t much of a problem because these kits are designed to fit current suspension systems, provided there is trunk space for the tank and compressor.
DISADVANTAGES
This isn’t to say, however, that everything is perfect for air suspension systems, and there are a few disadvantages.
Some truck drivers still argue that traditional leaf springs in an articulated truck can offer a better ride, regardless of the load. This could be partly due to the fact that air suspension can be about 50 kg heavier than leaf spring suspension. This extra weight could actually counteract the “better” handling offered by the lowered vehicle and make driving more difficult.
Since it weighs so much more, it might be possible to install other aerodynamic devices such as trailer skirts and cab side fairings to achieve the same fuel economy gains instead.
Leaf spring suspension is also much more durable and typically doesn’t require much maintenance for the first 5 to 7 years, after which it will need to be tightened. On the other hand, with air suspension, cars need to be serviced more frequently – up to 3 times the cost over the first ten years. Air suspension can leak, and you will need to keep a spare air line and other parts. Air suspension also needs to be tested more frequently, which takes time.
Although leaks are rare, finding them can be a bit frustrating. You will also lose some of your boot space. You need a decent-sized tank to prevent the noisy compressor from kicking in when you lift the car. Height changes are not as fast as with hydraulics.
Common air suspension problems can also be that the air suspension is inactive due to a leak or that the control unit is broken. The compressor could also fail, or the air tank could lose pressure. These all need to be repaired or replaced, which could cost you more due to repair costs at a garage.
THE VERDICT
So, what is it really like to have air suspension and use it daily? Better than most people might expect. A good kit, properly set up, will perform much better than conventional suspension in vans or trucks. For your average passenger vehicle, it might not be worth it, as regular suspension will serve you just fine. That said, people have happily drifted and set respectable lap times on air-ride setups, so if you have a particularly low-slung car, like a Porsche Carrera or almost any Mercedes S or E, it could be an option for you.
You will of course lose a bit of trunk space to the compressor and air tank, but no more than with a subwoofer box or a nitrous bottle, and there is very little weight disadvantage to adding the air-ride kit either.
Don’t be mistaken, however: air-ride doesn’t offer the instant height jumps that hydraulic systems do (you won’t be bouncing like a lowrider), but it really only takes a few seconds and with the right-sized tank can be done silently too. If you’re wondering if air suspension is reliable, rest assured that it is, and countless people have these systems on daily-driven cars without any problems.