Tuesday, August 9, 2016

Auto Air Suspensions Explained

Classic Car

Air Suspensions Explained

-Alan Arnell

Air suspension has been in the main stream in hot rodding for some time now, I will explain everything you need to know about them.

Today’s current state-of-art air system is an integrated, electronically controlled air suspension. Companies such as Ride Tech @ http://www.ridetech.com/ use a combination of ride-height sensors and air-pressure sensors to quickly achieve and maintain the desired user-selected ride height. Whether it is for looks, easy ride height alterations on the fly, handling improvements, or better load-carrying ability, air suspensions combined with huge wheels and tires are more and more chosen for Classic Chevy Hot Rods or Tri-Five Chevrolets.

What is it?

An Air suspension replaces conventional springs with air springs similar to those on big 18-wheel semi trucks.  Conventional coil-springs suspensions are the easiest to upgrade, with the airbags slipping right in place of the coil springs and often bolting to proprietary bolt-in brackets supplied by the aftermarket manufacturer.  

Why You Want One

The benefits, that is why.  Air suspensions have a wide tuning range for spring rate and load capacity.  A hot rodder using an air suspension may in just a few minutes via in-car adjust-ability easily and correctly tune the shocks and springs.  Unlike conventional systems an air suspension provides a much broader envelope so precise selection is not as critical as on a conventional spring

Image result for 1956 chevy on slalom course


Most air springs are progressive.  The more they compress, the stiffer they get.  Combine this inherent progressive spring rate with in-car adjust-ability and the result is enormous performance potential.  Tuning for conditions is quicker and faster.


We all have our own personal idea of how a car should ride and handle.  With an air suspension, these wishes can be accommodated with little or no component changes.  By adjusting the air pressure and shock valving, you can make the same care be soft and comfortable, firm and tight...or anywhere in between.  You can drive the car comfortably to the track, firm up the air pressure and shock valving to go racing, then readjust just the pressure and valving to return home in comfort.

How low can you go!


Air suspensions make it easy to lower the car so you can look cool!!!!  Air suspensions are great for the guy who just wants to lower his classic car a reasonable amount for a better looks without sacrificing any drivability or durability.  Most kits come set up to deliver a normal ride height that is several inches lower than the stock springs.  Regardless of how low the car is, air suspensions make it easy to raise the car back up for normal cruising, getting into a gas stations, or even rolling onto a trailer.

Air-Spring Design

There are three basic types of air springs available:  the double convoluted, the tapered-sleeve and the rolling sleeve.  The double-convoluted design looks like a large double cheeseburger and generally has more load capacity, a shorter stroke and more progressive spring rate that is best suited for use on most front suspensions where the spring sits considerably inboard or the suspension’s load point, which has the effect of multiplying load-capacity requirements while dividing travel requirements.  Tapered-and rolling sleeve air springs are smaller in diameter with a longer stroke and more linear spring rate; the are best suited for most rear end applications because there more travel requirements and fewer load-capacity requirements.

Basic Components

The basic components needed to equip a vehicle with air suspension have been in common use for decades, and consist of air springs, shocks, and air supply:

Air Springs

There is no mystery in air springs, but there are a multitude of options that range from air springs to custom tailor a suspension to a specific vehicle.


Shocks are the brains of your suspension. Replacing a conventional coil spring with an air spring doesn’t change this. Care has to be given on choosing the correct shock to make sure your suspension is as “smart” as you need it to be.

Air Source-Air compressors

At their most basic level, air springs can be inflated using external shop air just like t old air shocks, but that takes out one of the main benefits of this type of suspension: in-use adjustability to compensate for changing road conditions, vehicle loads or intended use.

To get the full benefits from an adjustability from air springs requires an on board air source.  With air suspension, ride-quality tuning is accomplished incrementally, with very small air-pressure changes.  Air springs have relatively low volume, so it is difficult to inflate or deflate them with external air in mall enough increments to fine-tune ride quality.  

An on-board air system consists of a least one air compressor, a storage air tank and a control system  Most classic cars work well with a 2-gallon tank kept full by a single compressor.  However, if you want the car to go up and down in two seconds it could take as much as a pair on 150-psi compressors and two or more 5-gallon tanks.

Air Lines

Commercial DOT-approved plastic air lines originally developed for big trucks are standard in most kits.  Typical operating pressures range from about 75 to 150 psi, well within the capabilities of such tubing.

For a custom look, you can fabricate stainless hard lines in place of the plastic lines.

Beyond Basic

We’re hot rodders, and that means basic just won’t do. We have taken the design and function of air suspension to new levels by engineering specific components to enhance your vehicle’s performance.

Innovative Shock & Spring Design

Many companies have invested significant resources to get the most performance from an air spring and shock combination in a wide range of applications. Take some time to study the different product lines.

High Tech Suspension Components

Getting the most from a suspension system means maximizing every aspect of the design. That is why companies offer tubular control arms, 4-link systems, and sway bars that are specifically engineered for different cars and  air suspension packages.

Sophisticated Control Systems

Advanced electronic controls to provide you with the simplest and most effective way to adjust your suspension. These systems will greatly increase your enjoyment of an air suspension.

Three ways to choose a system

You will find an almost staggering selection of air suspension choices on vendor websites. Don’t get overwhelmed, it really isn’t complicated; you can choose your system 3 ways – and each company will  be happy to help you through the decision process and find the right system for you.

Complete Air Suspension Kits from http://www.airbagit.com/

Complete Packages

One part number, one price, total solutions.  The web sites I looked at now offer multiple package levels for most popular applications to fit different customer desires and budgets. The complete package system is based on years of experience with outfitting each platform and will provide a simple solution to assembling all the right stuff in one easy step. It is as easy aw choosing a package and pick from a list of options.

Rear 1957 Chevy Air Springs

Front & Rear Systems

Most of the bolt-on systems are available as separate front / rear / compressor kits so you can pick & choose / mix & match to fit your specific vehicle or driving style. This path also allows you to build your system as you build your car, buying only the parts you need now.

1955 Chevy Front Suspension

Components for Special / Custom Applications

Thankfully the world of hot rodding is much more diverse than four or five dozen popular rides. We offer a large range of components that provide enough flexibility to fit nearly every vehicle. Unfortunately, we just can’t list every possible application in this catalog. If you drive a car that is just a bit off the beaten path, or is way out in left field, chances are very good we can get your ride on air just as easily as if it was a ’69 Camaro.

Suspension Tuning

Shocks and antisway bars are just as important on air suspensions a they are on a conventional suspension.  Whether metallic or air, suspension spring’s primary purpose is supporting the vehicle’s weight at a given ride height. Shocks control suspension oscillation.  Antisway bars control vehicle body roll to minimize suspension-geometry changes and weight transfer during cornering.

Air-suspensions experts recommend supporting the vehicle with as soft a spring as possible, relying on proper shocks and antisway bar-tuning to control oscillation and body roll.  Th9s maintains ride quality --one of the main reasons for installing air springs--while also enhancing cornering performance.  


Quality air springs have been proven in millions of miles of heavy-duty commercial vehicle use for more than 70 years.  So long as the air spring is not rubbing against anything and i is at least 2 inches away from hot exhaust pipes, they ought to outlast the vehicle.  

A Typical Air Suspension Diagram

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