Onboard air compressor & tank installation on home built skid plate

[SwampNut]

I just finished installing this system to allow me to air up all four tires at the same time, hands off. The system can be set for full pressure (200 PSI) or for tire pressure (36 PSI). It will auto-stop when it reaches that. Works great so far.

The trick to the dual selection is using two different pressure switches, and then a latching relay on the built-in aux connection. I'm still working on putting together a build list and URLs, I bought stuff here and there plus I had some parts around from previous projects. The latching relay basically switches mode every time it turns on. So the aux switch works like this: Press and get full pressure, press off, press and get tire pressure, press off, press and full pressure....etc.

This also works well to fill up my air jack (big inflatable jack, review to come on that soon too). I set it to tire pressure and it fills to a safe volume. Then set to full pressure and it continues filling, but it must be watched at this point since it would be over-inflated if not stopped manually.

I built the plate from scrap steel I had laying around, using a plasma cutter, welder, and grinder. Standard metal tools. Measured out to fit between the crossmember behind the transfer case and another member about two feet behind that. I used the stock 8mm holes in the forward crossmember, and had to add my own hardware (5/16") for the rear one.

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[capercrew02]

looks good! im hoping to do a tank install myself

 

[kickingaz]

looks good! im hoping to do a tank install myself

Build looks great! It looks like a single compressor install. I have the dual compressor Viair system that I am trying to determine how to install. I was waiting for the Maximus re-design but COVID delayed that. I may build a bracket that sits where the spare tire was as I don't believe my 38x13.50 will spare will fit under the JT.

 

[SwampNut]

I've heard that a 38 can fit if it's deflated. And if you have onboard air...

On the other hand that's a huge space that's easy to use for a compressor and tank. Also you and I are almost neighbors, and we have Jeep garage days most Saturdays.

 

[kickingaz]

I've heard that a 38 can fit if it's deflated. And if you have onboard air...

On the other hand that's a huge space that's easy to use for a compressor and tank. Also you and I are almost neighbors, and we have Jeep garage days most Saturdays.

I'll take you up on that one Saturday...thanks!

 

[Invictus Off Road]

I like this! I built my own rock sliders that I plan to turn into air tanks. I have used the Viar compressor before on my cj7. Did you move the air intake for the compressor up into the cab? Would be interested the relay write up when you have it done!

 

[SwampNut]

I have the air intake under the hood. In summer I'll probably just open the hood to run it, not sure. I might talk to Viair about it. I mean, I had my Viair system under the hood in the JK, so I guess it's going to live either way.

I haven't installed the relay, but have tested it. I'll get pics and a wiring diagram together as soon as I know it works properly in actual practice.

 

[e36racer]

Great build (and idea for that matter). I've been thinking about a similar mount setup, except with a scuba tank instead. That way I won't need an onboard compressor, since an LP80 tank at 3,000psi is plenty to fill four 37" tires from flat. But I'd like to copy your dual pressure outputs.

 

[SwampNut]

I'd be worried about what can happen to an aluminum tank next to the exhaust like that. They aren't meant to be heat cycled, and heat cycling aluminum makes it brittle. For some alloys the hardening temp is quite low, under 400. I don't know if that applies to tanks specifically. I would carefully caution you to research it. But it would be no big deal to rig the two outlets to a regulator. I basically just used generic bulkhead fittings, and compression fittings for hard plastic tubing.

 

[radioinstl]

I'd be worried about what can happen to an aluminum tank next to the exhaust like that. They aren't meant to be heat cycled, and heat cycling aluminum makes it brittle. For some alloys the hardening temp is quite low, under 400. I don't know if that applies to tanks specifically. I would carefully caution you to research it. But it would be no big deal to rig the two outlets to a regulator. I basically just used generic bulkhead fittings, and compression fittings for hard plastic tubing.

Use a Fire Department SCBA tank. 4500 Psi and meant for heat

 

[SwampNut]

That is potentially dangerous advice. "Heat" in that context means something human survivable, not being next to a muffler at 500 degrees or an exhaust pipe at 800+.

 

[radioinstl]

That is potentially dangerous advice. "Heat" in that context means something human survivable, not being next to a muffler at 500 degrees or an exhaust pipe at 800+.

Not accurate at all. Firefighting SCBA are testing with both direct flame impingement and at 500 deg F for 5 min. Seeing his mount acts as heat shield, you would be fine. If worried just add some aluminum insulation tape on the out side of the bracket

 

[SwampNut]

Exactly, not 500-800 degrees for hours.

 

[e36racer]

Good point about the exhaust, I didn't consider that. I'd imagine a simple heat shield would be sufficient.

 

[SwampNut]

Possibly. It's a situation where you just don't know what might happen, and the energy storage in a tank is tremendous. I used to use a dive shop that left one embedded in a double block wall to remind employees what happened when someone was careless. Long-term heat cycling embrittles many alloys unpredictably. I really wouldn't mess with this. The heat shield will keep the worst heat off, but the tank will spend hours at 300++ degrees.

The risks are pretty big.

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