OBA Install

By Paul Blaik

Well as everyone knows - deflating your tires prior to wheeling & re-inflating them after the run is as ceremonial as dealing with sway-bar disconnects!  All is not as fun as you would hope, the problem arises when it takes about 20 minutes a tire to refill a 33" tire with a little 12v compressor, not to mention 4 of them.  The alternative of finding a local service station to refill at, often is a daunting task in itself, especially at 7 PSI.  I had planned on buying a Quick Air II to improve the situation as one of my hopeful project until I saw how fast a engine driven compressor was able to inflate tires.  A buddy of mine Wkndboy had fabed his own brackets, pressure switch, solenoid activated rotary compressor in his YJ.  He was able to fill the tires of three Jeeps in the time another buddy was able to fill two tires with a little 12v job!!  My interest was born.

Enter the York compressor.  I was familiar with this option from articles I had read on many personal Jeep pages, tech reviews on on-line Jeep magazines & an article in Peterson's 4WD.  This popular compressor is able to put out large quantities of air in short periods of time and is  available from numerous sources.  So my decision was made, now I just had to buy the hardware.  Plans changed though as I was luckily given my NEW York compressor along with Kilby Enterprises' Onboard Air brackets, clutch & dual alternator pulley as a Christmas present from my Jeep chick Fiancée, Kathleen!  

I began my research phase, reading all I could from as may sources as possible with detailed installs.  I bombarded Brad Kilby of Kilby Enterprises/Onboard Air.Com with questions & began sourcing my parts required to complete the installation.

I concluded I needed the following parts, not including piping/tubing:

1. 3/8" Coalescing Oil Filter - Speedair # 
2. 3/8" Genie Check Valve/Unloader - #
3. 2-1/2" 0-200 PSI Pressure Gauge for engine compartment
4. 95-125 PSI Pressure Switch - Square D #
5. 135 PSI Safety Relief Valve - Included with Kilby Kit
6. 3/8" Water Filter - Cambellfeild Hass #
7. 3 Gallon Tank - Kilby #KE-AT2.5
8. 3 x Quick Connects
9. Pressure Regulator (for ARB outlet) - Cambellfeild Hass #
10. Illuminated Power Switch
11. 2" 0-200 PSI Pressure Gauge for interior of Jeep
12. 3/8" Brass Cross
13. 3/8" - 3x 1/4" Manifold
14. 1/2" intake filter - Kilby #FS-07-050

Installing the compressor turned out to be quite a simple task.  The installation instructions provided were easy to follow.  The two most difficult parts of the installation proved to be removing the stock alternator pulley without the aid of an impact gun (I had to heat the bolt & clamp the pulley in a vise to get it off) & actually tightening the bolts that hold the compressor on the bracketry.  I had no other problems & had already made space for the compressor itself by removing the stock air intake box & installing a K & N filter the week before.  I was aware that some installs (depending on the configuration of your Jeep) could require trimming the inner fender-wall to allow room for the large compressor.  Luckily I didn't have to do that, but I did have to put a few bends in the passengers side support rod & use washers as spacers on the firewall & the grill side.


In piping the system,  all fitting I used are brass & the lines were kept 3/8" wherever possible & reduced to 1/4" where required.  Apparently the air coming out of the compressor can be extremely hot & standard red rubber airline hose has been known to blow as a result.  To address this I used 12 inches of 1/2" stainless steel braided hose prior to the reducing coupling that connects the oil filter.  This seems to be sufficient in allowing the air to cool prior to reaching the oil filter, check valve, tank - hosing.  I also installed a 3 gallon tank, since to me the tank was important, since I want to be able to run air tools in addition to being able to fill my tires after a trail run.
  You can see in this shot, the line of order after the compressor.  The grey canister is the Kilby inlet filter which connects a 90 elbow then into the compressor which is to the right of this picture.  On the outboard side is the stainless steel hose that comes out of the compressor to a 1/2"x3/8" brass reducing coupling into the coalescing oil filter, genie check valve into a tee which continues on to the tank & also diverts air back to the control cluster.  The coalescing oil filter is mounted the the inner fender-wall on a custom welded bracket (compliments of Wkndboy).

The control cluster is mounted to the side of the York compress on another custom welded bracket (again compliments of Wkndboy).  Here a 3/8" x 3x 1/4" manifold has a 135 PSI safety relief vale, 0-200 PSI pressure gauge & a 40PSI differential pressure switch set 95-125 PSI, mounted.

  From the 3/8" tee flexible high pressure hose was used to route to the 3 gallon tank.  The tank was mounted in the engine compartment to keep clear of dirt & debris in the alternative mounting location under the Jeep.  The tank was mounted on a piece of angle iron, little U-bolts were used to fasted the angle iron to the support rods.  The mounting itself is very solid & is easily removed for engine work.  There is very little clearance on the top side of the tank, the ends of the U-bolts had to be trimmed & the engine compartment light had to be relocated.

On the out side of the tank, again high pressure flexible hose was used.  The hose first goes to a inline water filter that is mounted to the last custom welded bracket (also compliments of Wkndboy), to a 4 way 3/8" brass cross.  This cross diverts air to it's final destinations... one quick connect in the engine bay & one on the front & rear bumpers.  In this shot, you can see I have a coiled hose plugged into the engine bay quick connect.

On the front side port of the tank I have mounted a pressure regulator.  This regulator is rated a 300PSI input with capabilities of regulating the flow up to 125 PSI.  Although I do not currently have ARB air actuated lockers I WILL SOON, & I will be using this OBA system to run the lockers which need to have a regulated supply of 90 PSI.   

Lastly, but one of the slickest parts of my install in my opinion, is the internal 0-200 PSI pressure gauge & the illuminated system power switch.  This switch is wired to a ignition switched 12v power source & to the pressure switch.  When turned on the pressure switch will turn on & off as required to maintain the system pressure between the 95-125 PSI setting.  I used flexible stainless steel braided hose to connect the bottom port of the air tank to the pressure gauge that you see mounted in the center console.  The hose has bee routed through the rubber grommet in the firewall!

Final thoughts:  This install took way longer than I expected.  I'm ashamed to say it took over 20 hours to complete the install to my satisfaction :)  Numerous changes were made along the way & most of the delays were due to pondering what if? scenarios.  Nothing was HARD about the install rather planning, decision making & last minute runs to Home Depot for missing parts.  After testing the system I can say I am extremely happy with the end results.  I may at a later date, install an additional/or additional tanks under the Jeep too.  The more air storage you have the less the compressor cycles, therefore reducing possibilities for overheating & preventing slowdowns from lack of air volume. 

Cost:  Astronomical!  As it seems all cool upgrades are.  As usual being Canadian helps drive the price through the roof, shipping, duties, taxes & brokerage always add up to total I'd rather pretend not to realize.  However in this case, I am lucky since my girl bought the two most expensive pieces as a Christmas present (man it's amazing what you get as a result of buying an engagement ring!!!).  All the little pieces & components add up quickly & so do the air tools that I've bought as a result.  However the end result is very cool & I am quite proud of my Jeep's latest addition....  It all comes together at a whopping $1100.00 CAN (not including air tools).



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