York Compressor
    In order to run the ARB lockers I needed a good compressed air source.  I also wanted air to run tools and to air up tires.  I looked around to see what others had done and found three popular methods.  The first and easiest method was to use the ARB compressor kit.  The compressor is small and comes with a wiring harness to make installation a breeze.  I was convinced that this was the best solution and actually bought the kit.  But, after careful consideration, I decided the ARB wasn't really ideal for all the chores I had in mind (running air tools and airing up tires) so I sold it to a friend.  A second popular choice was the Sun Performance Quick Air II.  Like the ARB, it is small, but it offers a slightly greater volume of air.  In the end, I rejected the Quick Air for the same reason...not enough air volume.  The last popular choice was to install a York air conditioner compressor.  Kits for the YJ and CJ were available, but none for the TJ.  I called up Therold Enterprises to ask about mounting their YJ kit on a TJ and they said no one had done it and it didn't look promising.  The owner also told me he was retiring and had only one YJ kit left.  He sold me the kit at a very good discount and promised to take it back if it didn't work well.

    In addition to the bracket kit, I also bought a brand new York compressor from Therold.  The unit he sells is the highly desirable long stroke version that puts out monster amounts of air.  Here's what the compressor looks like from the side and the front.  Notice the orange manifolds that adapt the York input and output to standard pipe threads:

    He also supplied me with a number of air fittings and his special air manifolds to adapt the compressor to standard pipe fittings.  He suggested I add some type of reservoir to store air for better performance airing tires and running tools and also to prevent the pump from cycling continuously when running the ARBs.  I found a great tank from Sun Performance that holds 2.5 gallons.  Here's the complete parts list for the project:

 
York Compressor with electric clutch
Bracket kit
Sun Performance air tank
2 - 1/2" male x 1/2" hose nipples
18" - 1/2" high pressure hose
2 - 1/2" hose clamps
1 - 1/2" female x 1/2" male street elbow
1 - 1/2' female x 1/2" female check valve
1 - 1/2" male x 3/8" male reducer
1 - 3/8" male hex nipple
1 - 3/8" female T fitting
1 - 3/8" male x 3/8" hose nipples
48" - 3/8" high pressure hose
4 - 3/8" hose clamps
1 - 3/8" quick disconnect set
1 - 3/8" male x 1/4" female reducer
1 - 1/4" male pressure gauge 0-160 PSI
3 - 1/4" male hex nipple
3 - 1/4" female T fitting
1 - 1/4" male 175 PSI pop safety valve
1 - 1/4" male heavy duty adjustable pressure switch
2 - 1/4" male x 3/8" hose nipples
1 - 1/4" female 0-150 PSI pressure regulator 
1 - 1/4" male 100 PSI pop safety valve
2 - 1/4" male x 1/8" male reducer
2 - ARB solenoids
2 - braided stainless steel hoses with fittings
1 - 1/4" tank drain cock
18 gauge wire
1 - relay
2 - 5/16" U-bolts
1/8" x 5" x 36" scrap aluminum for tank bracket

    All the small items were sourced from the McMaster-Carr catalog.  The stainless hoses came from JB Conversions.  Here's a picture of most of the small parts:




    Here's a picture of the regulator manifold I put together:

    I also used the following tools to complete the install:
 

3/8" electric drill and bits
Assrted hand tools
3/8" pipe tap
Wire crimpers
Teflon pipe tape
Plasma cutter
POR-15 paint
LokTite 271 thread locker

    Here is a diagram of the complete system.  Glenn Bontly made the diagram for me after seeing the crappy hand drawn schematics I had previously. Click the picture to see a larger version:

    Here are the steps I followed to install the brackets and compressor.  I also had to have one of the stock air conditioner hoses lengthened and relocated and I had to cut the inner fender to make room for the pump.  This might not have been necessary if I did not have a body lift.  The instructions for mounting the compressor were good, but I added a few steps and simplified a few others.  I used LokTite on all the bolts that did not have nylock nuts:

1.  Loosen and remove the serpentine belt from the alternator.
2.  Remove the alternator and replace the stock single serpentine pulley with the new double seprentine/v-belt pulley. 
3.  Reinstall the alternator and the serpentine belt.
4.  Loosen the 4 bolts that hold the factory air conditioner in place.  Remove the two inboard bolts and slip the spacer between the factory compressor and the factory bracket.  Install the brace bracket on top of the factory compressor.  This might require bending the factory air conditioning hard lines.  Replace the bolts but do not tighten.
5.  Remove the 2 outboard bolts and slip the large bracket between the factory compressor and the factory bracket.  Replace the bolts and tighten all 4 bolts.  Bolt the brace to the large bracket.

    Here are two detail shots of the brackets.  The first is viewed from the side and the second is viewed from the front of the jeep.  Note how the factory air conditioner hard lines have been bent slightly to allow the brace bracket to be installed:

6.  Place the York compressor against the brackets and determine how much of the fender must be cut.  Mark the fender.  Also determine how you will re-route the air conditioner line that is attached to the fender.
7.  Remove the brackets. 
8.  Cut the excess metal from the fender.  Don't forget to paint the raw edge.  I used POR-15 to protect the edge.
9.  Go to an air conditioner repair shop and have the system  discharged.  Have a new line made to clear the York compressor.  I had mine routed down to the frame, then back up behind the York.  Recharge the air conditioning system.
10.  Bolt the York to the brackets and snug the bolts.
11.  Re-install the brackets/compressor per the instructions in steps 4 and 5.
12.  Place the v-belt on the inner pulley of the clutch and the v-belt groove of the pulley you installed in step 2.  Use a pry bar to raise the York on the bracket and tighten all 4 bolts to keep the belt tight.

    Here are detail shots of the compressor installed on the brackets.  They are from the side, front, top/side, and bottom/side.  Note the new pulley (rusted) below the York's clutch pulley.  The yellow highlight shows where the fender was cut:
 
 

13.  Choose a suitable location for the tank.  I chose to mount mine across the top of the engine.  I made a bracket from some scrap aluminum so the tank could hang on the grill prop rods.  The bracket went through several prototypes before I came up with a good compromise of engine and hood clearance.

    Here's picture of the tank installed in the jeep.  Everything is plumbed and wired in this picture.  After this photo was taken, all the wiring was loomed for a neater appearance.  The tank has about 2" of clearance above the engine and the spark plugs and dipstick are easily removed:



 
 
 

14.  Plumb the air lines.  I tapped the end fittings on the tank to 3/8" to allow more air flow into the tank and into tools or tires.  The rest were left at 1/4".  I used a check valve at one end of the tank to allow the compressor to start more easily and to prevent the tank leaking down pressure through the compressor.  At the other end of the tank are the pressure gauge and a hose running to the bumper for filling tires and running tools.  They are attached to the tank with a hex nipple and a T fitting.  The end of the hose attaches to a quick disconnect mounted on the bumper.  On the back side of the tank are the pressure switch and a 175 PSI pop safety valve connected to the tank with a T fitting and a hex nipple.  The pop safety valve ensures the tank pressure does not get too high if the switch fails or the tank gets too hot.  At the bottom of the tank is a drain cock to drain moisture if any accumulates in the tank.  At top of the tank is an elbow nipple and a hose running to the regulator manifold.  The air is taken off the top of the tank to prevent liquids entering the line.
15.  Mount the regulator.  I chose to mount mine on the ABS tray below the vacuum booster and master cylinder.  The manifold consists of a regulator, a 100 PSI pop-safety valve, and 2 ARB solenoids connected with T fittings, hex nipples, and reducers.  The pop safety valve is there to ensure the ARBs don't get too much pressure if the regulator fails.

    Here's a detail shot of the manifold mounted on the ABS tray:
 
 



 
 
 

16.  Wire the electric clutch directly to the battery and start up the engine.  This will pressurize the system and test the 175 PSI pop safety valve on the tank.  Disconnect the clutch and check the system for air leaks.  Test the 100 PSI pop safety valve by turning the regulator up.  Set the regulator for 80 PSI.
17.  Wire the electrics for the system.  I used 3 switches (see my 6-switch panel page) to control the system.  The master switch applies power to the pressure switch and to the other 2 switches.  It is wired to the ignition so the system will not work with the key off and drain the battery.  From the pressure switch, a wire runs as a trigger for a relay controlling the clutch.  The clutch can draw a lot of amperage and should run from a relay and not from the switches directly.  The other switches are wired to the ARB solenoids.
18.  Loom all the wires for a neater appearance.

    Overall, I'm very satisfied with the setup.  The cost was a bit more than I had planned to spend, but could have been reduced if I didn't have air conditioning or if I had used a junk yard compressor.  I'm happy I chose to use new parts for the piece of mind they bring.  In the future, I plan to replace the rubber hoses with stainless steel braided lines.

    As for performance, I couldn't be happier.  As a test, I used my Quadraflate to air down the tires of my Expedition to 3 PSI and then used the York to air them back up to 40 PSI.  It took just over 2 minutes to air them all up simultaneously!  The compressor does get a bit hot, but seems to run just fine.