Let's face it: Plastic air line is a simple yet vulnerable way to plumb trucks with air-ride suspensions. It may get the job done, but if you are not careful, a failure could leave you stranded on the road. We have heard countless stories of truck owners misplacing plastic line and winding up trying to salvage their rides because the line broke while driving at highway speeds. In a nutshell, plastic line is more susceptible to fail with heat, and since it is flexible, it can move into a position that can puncture it.
On the other hand, an air system can be set up with metal hard line by taking just a few extra steps. For the beginner, we suggest taking your time to map out a safe route and take good measurements to make sure you don't waste too much material. Though many people use different material, 1/2-inch od Type L copper is safe, industrial-grade tubing, and it is easy to work with. For a truck with a front and back system, you will need about 60 feet of copper tubing, and for a truck with FBSS, you will need about 90 feet of material. With time and practice, it will probably take less material than these suggested lengths, but chances are you will make some mistakes your first time around. You should avoid hot areas such as the exhaust, and prevent vibrations against sharp metal. Other than that, hard lining should be a safe and simple way for you to hook up an air system.
Ekstensive Plumbing:
While our project Chevy S-10 was getting work done at Ekstensive Metalworks, the air system was in desperate need of an overhaul. All of the valves, fittings, and plastic lines were disassembled. From there, we added some of the nickel-plated push-lock fittings, which Ekstensive sells and installs on all vehicles. | 
These all-metal fittings are top-quality and will prevent leaks at this line connection. Once assembled, all of the valves were secured to a custom mount that was welded to the frame. | 
With plenty of 1/2-inch-od Type L copper tubing, the length measurements were taken and marked the end of our 90-degree angle. This mark was lined up to the handle of this Matco Tools pipe bender, PN MST370FH, and the line was bent when the tool's handles were pushed together. |
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The last step was repeated until the tubing had all of the correct bends we needed. Then, a regular pipe cutter was used to break off our piece. | 
To keep things simple, we decided to run a single line from the air tanks to supply all of the inlet valves with pressurized air. Three T-fittings were put in place, and lines were run to all four valve assemblies. |
Since the airbags on the front suspension mount in these frame pockets, a hole was drilled in the frame to lead our copper line directly to the top of the airbags. Then, a 90-degree elbow fitting will link the line to the airbag. | 
The line that supplies the front passenger-side airbag has to go around the exhaust and driveshaft. To do this, the pipe bender was used to run the line behind the transmission crossmember and to the valve assembly. |  |
With the air tanks and two 'bags out back, three lines had to be run over the rear axle. The lines were measured to follow the frame and the step notch. Afterward, they were connected to their designated components and clamped to the step notch. |  | 
The Final Word
With all of our copper tubing bent, cut, and in place, all that was left to do was to wire the valve assembly. Keep in mind, once the air is in the system, it is a good idea to spray soapy water over all of the connections. This will make any leaks visible, and if any should be present, it can be quickly fixed by tightening the leaky fitting. When everything is airtight, you will be good to go and feel safe knowing that the copper hard lines are dependable. |