Ups and Downs of Air Ride

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Aug2012 06


*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

If you’ve been to a show or visited a forum within the past five years or so, you’ve most likely had some exposure to air ride suspensions. At Apex Tuning, we’ve installed air ride systems on several cars and had dozens of customers asking about them. What are the benefits? What are the drawbacks? And, most commonly, how much does it cost? The goal of this article is to clear up the confusion and clearly outline the ups and downs… [yes, pun intended] To begin, it is important to become familiar with the components of an air suspension system and how they all work together.

The Air Shock/Strut/Spring
This is the air bag itself. While there are many different styles available, the air strut is the most common in VW applications. It is basically a load bearing shock with the spring attached (like in the picture above). Some VW applications, such as the rear end of the MK4 and MK5, use an air bag, or air spring, in conjunction with a separate shock absorber. This varies by manufacturer.

Names like “Bagyard Bombers” and “Air Lift Slam Series” get thrown around a lot. These describe the air bag itself, and the air bag defines the range of suspension travel which varies based on the actual bag design. An air bag or air spring, functionally, does the same job as a coil spring in that it carries the load of the vehicle. The bag has a fitting for hooking up an air line which is connected to the air management system.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Air Management Package
The air management package contains the parts that actually control the system, taking input from the driver at the interface and translating that into pressure changes in the bags. It does this by adding or removing compressed air from the air bags through a system of air lines and valves. The A.M.P. also controls when the compressor(s) will kick on to refill the storage tank.

To best illustrate how everything works together, we will follow the air though its journey within the air suspension system. Air is pulled into the compressor through a filter, which can be either mounted directly on the compressor or in a remote location and connected to the compressor via an air line. The compressor pumps the air into a storage tank, where it is pressurized to 125-200 psi, depending on the particular setup. After leaving the tank, the air travels through a moisture trap to ensure a supply of dry, clean air. It then travels through a system of valves, which control when and how much air is sent through the air lines to each individual air bag. The same valves will allow the air to escape when reducing bag pressure, either venting it directly to the atmosphere or through an exhaust muffler to minimize noise.

There are three major differences when distinguishing one management package from another: the valve (manual or solenoid), the controller/interface, and the method for monitoring ride height.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Valves
A manual valve physically opens and closes without electronics. Think of a sink faucet. You move the handle and it opens up allowing the fluid to flow. There are no electronics in a manual valve setup, making it the most basic and, typically, the lowest cost setup as far as parts are concerned. This type of valve requires air lines to be run directly to the valve. This can significantly increase the amount of labor required for installation, as well as the amount of air line necessary to plumb the system. Additionally, manual valve systems should have pressure gauges for each bag so that the pressures can be set to the correct level, and these systems will lack certain features such as ride height presets.

A solenoid valve is nothing more than an electrically actuated valve. These are used in systems labeled analog or digital, and open or close when receiving a signal, either from a computer or electrical switch (more on that in a bit). Each air bag has its own distinct solenoid valve (4, typically) and some companies offer a single unit that contains several solenoids, such as the VU4 from Accuair. Solenoid valve setups allow a lot more flexibility for installation, and use wiring instead of air lines to the switch, allowing for an easier installation.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Controller
The air ride controller is the electrical/electronic system that manages the operation of the valves and compressors. This can vary greatly in complexity, operation, and features.

On a manual valve setup, the only part of the system that needs electrical control is the compressor. This is typically done using a simple pressure switch which is used to trigger a relay, causing the compressor(s) to pressurize the tank.

On systems that use solenoid valves, there are several different configurations. An analog system will operate much like a manual system, the main difference being the type of valve regulating air to the bags. The compressor is still controlled using a pressure switch and relay. There will typically be four electrical switches, each one operating one solenoid. This type of system has no pressure monitoring, so, much like the manual system, it is a good idea to have gauges to determine the pressure in each air bag.

For digital systems, many different features and options are available. These will typically have a user interface that is a touch pad or digital display/controller unit. Digital systems use an ECU to control the ride settings and turn the compressor(s) on and off. There are also controllers that use a single programmable rocker switch for simple up/down operation, either between preset heights or to individually control each bag. Most digital systems use pressure to recall height presets.

A very popular option for digital management packages is the addition of ride height sensors. One of the most popular is the E-Level system from Accuair. For these systems, the suspension height presets are based on ride height instead of pressure. This has the added feature of auto leveling the vehicle when loaded, so you can be sure your ride height is consistent whether the vehicle is empty or carrying 4 adults and a trunk full of junk. The E-Level system is available with a rocker switch or touchpad interface, giving the user easy-to-understand controls while having the features of a ride-height monitoring digital air management system.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Safety
Many modern air ride systems have a few safety features installed, including tank pressure monitors and thermal protection for the compressors. It is also important to note, both for safety and longevity, that DOT rated air line and fittings should be used for any air suspension system.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Compressors
When selecting an air suspension system, you should keep in mind that one of the most important parts of the system is the air compressor. There is a lot of discussion on whether the use of two compressors is worth the added cost. When selecting a compressor, or compressors, there are a few factors to keep an eye on. Fill time will be shorter with two compressors, or with compressors that provide a larger flow rate. Compressor duty cycle is almost as important as the flow rate, and compressors rated for a higher duty cycle will be able to run longer without overheating. One commonly overlooked aspect is noise. Not only do different compressors create different amounts of noise, the fill time will also dictate how long that noise will be created. A quieter compressor with a shorter fill time will really make a huge difference in driving comfort.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Air Tank
The air tank is a pretty simple concept. It holds compressed air to allow the air bags to fill more quickly than with a compressor alone. A buffer, if you will. The ideal tank will be determined based on a few criteria. The size of the tank is a pretty obvious one. It should provide enough air buffer to maintain functionality while being able to fit in the space provided where it will be mounted. Three and five gallon tanks are popular options. The tank should have enough bungs to allow the compressor feed, output to the valves, a drain for moisture, and additional bungs for any additional air accessories. The tank should be one designed for compressed air, as safety is an issue when you are dealing with a pressure vessel. There are tons of mounting options, some of which also provide mounts for the digital controller, solenoids, and/or compressors.

Now that we’ve discussed all of the parts in an air suspension setup, it is time to weigh the benefits and drawbacks of air ride to determine if it is right for your application.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Ups
The biggest benefit of air ride suspension is the fact that ride height is easily and quickly adjustable. That is important for several reasons. Your car can be low, very low, when parked or driving slowly, but you can raise it if necessary. This may not seem like a huge deal until you encounter a speed bump or decide to let your friend take your car for a drive. It will allow you to raise the car when cruising on the highway or driving long distances, avoiding the problems associated with extreme lowering and the resulting changes in suspension geometry and alignment, which can wear out tires and axles. Air suspension also gives you a smooth ride, which is also nice on those long drives. Of course, in the VW/Audi scene, lower is better. We’ve all heard the old adage “If you ain’t rubbin, you ain’t dubbin” which is a testament to this mindset. If you want to be able to get low without the headaches that arise when trying to drive your car with almost no ground clearance, air is a good option. An added bonus is the convenience of always having compressed air available for filling tires or using pneumatic tools.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

Downs
While there are some great benefits of air ride systems, there are also some drawbacks. Due to the complexity of air setups, and the number of individual parts involved, the costs involved are higher than most alternatives. While the type of management and features will affect the cost, most kits range from $1500-$4000 for the parts alone. After you add the cost of install and other materials to make the install aesthetically pleasing, it becomes quite an investment. The number of parts involved also means there are a lot of potential failure points in the system. You could blow a bag, pop an air line, or have a valve fail, any of which would leave the car stranded as the suspension will bottom out if no pressure can be held in the air bag. There is also more maintenance involved with the keep the system running as it should, from cleaning filters to draining moisture from the tank.

Air suspension setups are, for sure, designed for comfort and adjustability, which means they are not ideal for high performance applications. If you go to the track regularly, you should certainly look at other options. While air ride allows you to adjust the car to a safe driving position, the alignment will change as you change the ride height, which can wear out parts if you drive it lower or higher than it was when the alignment was set. There is also the risk of accidentally pushing the down button while you are driving, which can damage the vehicle.

Another big thing we’ve seen all to many times is the way it changes how wheels fit. Lowering the car all the way until the subframe hits pavement will cause the wheels to tuck up into the wheel well. Most air suspension systems we install require the owner to swap out for a different wheel setup, as their old wheels no longer fit. Scraping frame, as they say, will also require the unibody to be notched for clearance. This is usually only an issue with the passenger side axle, but it will be an added expense if you want to go really low.

On top of all of this, you do lose some functionality of the vehicle, as the components take up a lot of space. Typically the components will be installed in the trunk area, so you lose cargo space, or, often, the ability to carry a spare tire, depending on how everything is mounted. There will be more noise in the car when the compressors are on. This can be minimized when selecting the components, but the compressors will come on at some point.

All in all, air suspension systems can be a great addition to your vehicle if the benefits outweigh the drawbacks. If you have any questions about air ride, pricing, or how it will affect your vehicle, feel free to contact us.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

For the complete series of Suspension Tech posts, check out this link.

*** DISCLAIMER – WE ARE A Volkswagen/Audi SHOP. WE CAN’T OFFER ADVICE FOR AIR RIDE INSTALLATIONS ON OTHER MAKES.

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About Apex Tuning is an independent mechanic shop specializing in Service, Repair, Maintenance, Diagnostics and Performance Tuning for VW and Audi vehicles.  Based in Raleigh, NC we are just a short drive from anywhere in the triangle region.
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