On-Board Air

Page 3

Mounting the compressor

As each installation will be different we won't go into deep detail here as to how we mounted our OBA compressors. It is up to the installer to determine what will work best for their situation. Attention should be paid to making sure the compressor is lined up with the belt at the correct angles and runs true over the pulley. You must also make sure that the belt makes contact with at least 1/4 of any pulley it runs over or around except for idler pulleys if needed/installed. Here are a few pictures of how we have installed our compressors though.


Once the compressor is mounted you can run a string around all the pulleys in the path the belt will take to figure out approximately how much longer a belt you will need.  We have found that Napa stocks a good supply of belts.  Once you have a length figured out be sure to buy one size larger and one smaller to avoid repeated trips back to the parts store if the one you pick out isn't right.

As stated before it is important that you maintain the original fittings and a section of the tubing that connected to the compressor when you get one out of the wrecking yard.  This is because you can use a tubing cutter and cut the tubing at a straight spot on the tube then use a standard brass compression fittings available at about any hardware store to connect to and provide a standard thread fitting on the tube to which to work from.  Generally the intake side uses 5/8" compression fittings and the output uses 1/2" fittings.


Cut tubing to accept compression fittings                            Compression fittings installed         

The remainder of the process involves mounting an air distribution block also known as an air manifold, a tank and connecting everything together.  The air manifold needs to be mounted in a convenient location.  At the input of the block we attach the filter/regulator.  For the output you should have an air quick disconnect for attaching a hose for filling your tires or blowing the dust out of your rig with a duster gun.  You also use the air manifold as a mounting location for your locker solenoids and air horn solenoid of so equipped.  We tend to make our own out of a solid piece of billet aluminum so that we can custom size and shape to fit the intended mounting location.

Air manifold.  ARB solenoids at bottom, Air hose disconnect and air horn solenoid on top

7/8" rubber crutch tips available at just about any hardware store can be used as caps on the air hose quick disconnect to keep out water and mud.

Air tanks are available in a variety of sizes from many suppliers however as we use a triangulated 4-link long arm suspension we find it necessary to make our own to fit the small space we have available.  We typically get a length of 1/8" wall 6" diameter tube cut at the metal market as well as two 1/4" thick end plates cut from a piece of 6" diameter solid bar stock and weld it together to form our tanks.

Lastly everything has to be plumbed together.  We prefer to use 3/8" nylon air brake line.  The line is easy to work with, durable and comes in a variety of colors.  For connections we use push-to-connect fittings.  These fittings are available in brass or plastic and require no tools to connect or disconnect your lines.  To connect you simply push the tube into them and then give a slight tug to seat.  To disconnect you hold in a collar and pull the tube out.



One other nice feature is to add an in-cab air pressure gauge.  With the limited space in most Jeep's this can be a bit of a challenge sometimes.  We opted to remove the air bag disconnect switch from it's panel, cut out a hole and install our gauge in that spot.  The air bag switch was something that was only put on a few model years because the government dropped the requirement for them and we never used it anyway.  Since the switch cannot really be taken out or the system won't work, we just stuffed it up inside the dash.



There are many sources for parts to build your OBA system.  Keep in mind what we said on page one.  Sites dedicated to 4x4 OBA setups tend to over charge for these components.  If you have a business license you can order almost all of it through WW Grainger.  If you don't have a business license, well, think about getting one as in most states they do not cost much and you can apply online for them.  Following is a list of component suppliers.

WW Grainger

Reid Tool


Quality Air ride

Northern Tool

Harbor Freight


Kilby Enterprises





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