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Hi, just wanted to share my “hidden” on-board air install in case it might be helpful to someone else.
I don’t air down often, but when you need a compressor, you need a compressor. So, I went with the single motor ARB CMK12 based on my use case. The set-up had to be:
It was tricky getting the mounting plate inside the body cutout then attaching the compressor. I ended up taking the compressor base plate off and pressing some stainless steel carriage bolts into the mounting plate. I then spent an hour aligning and screwing in the 4 vibration isolating bolts to re-attach the compressor inside the body. I ran the wiring down to the frame, then though the frame and up into the engine bay. For the plumbing I used ARB’s 3-ft braided stainless steel PTFE hose and cut a hole in the fuel housing to mount an ARB hose coupling with dust cap. I was very careful to route the hose as far away as possible from any wires or fuel line as this hose will get very hot. There is a JL fuel door with air fitting available but I just mounted it directly to the fuel door housing. When you filling-up you can't even see the air fitting, and it is not in the way of the gas cap. Which is important because the 392 likes gas.
The ARB wire harness is not very long, so I bought 2 spools of 8 gauge wire (red & black) to connect the compressor to the battery, and 2 spools of 18 gauge wire (red & black) to connect the 40A relay to the negative of the battery terminal and the factory AUX #2 to turn on the compressor from the cabin. There is a great video on the Wayalife youtube channel explaining how this all works. I used inline soldered splice to "lengthen" the ARB wire harness to reach the engine bay. After that I used some automotive heat shrink tubing and some Tesa tape to wrap it all up.
Finally in the engine bay I used an inline splice on the red 8 gauge + wire to reattach the 40A ARB fuse. I ran all the wire up from the frame and inside the wire track (chase) along the firewall. Then I used a ARB fuse bracket from American Adventure Lab to secure the 40A fuse to the firewall, and I connected all the wires. I wanted the run from the battery to the fuse to be as short as possible so being able to attach the fuse to the firewall with a bracket was very helpful, plus the bracket was very well made by AAL.
Finally I need to add the air accessories. I picked up a couple air hoses. I shortened the Flexzilla hose to allow it to nest inside the longer hose. I added a pair of Haltec H-5265 lock-on air chucks, and I built a 3-way manifold to allow two tries to be inflated simultaneously. I also added an old Milton inflator and CH tire gauge I had lying around. I wanted to keep everything standard ¼” brass industrial couplings for reliability and compatibility. I ordered some deflators from an Aussie company called iCheck TPMS which work great and hit the target pressure of 15psi within ½ a psi. Everything is designed to fit into the space used by the jack, easy to access and most importantly always available onboard the Jeep. And the plastic cover fits over it keeping everything nice and clean.
So with it all set-up it was time to test it out. I went ahead and timed everything. I used the iCheck TPMS to deflate.
Deflate:
All 4 tires simultaneously:
To air back up I did one side filling each tire individually. On the other side I filled both tires at once using the 3-way valve. I was curious if the times would be any different. They ended up about the same.
I also wanted to monitor how hot the compressor got and how hot the fuel intake and the tail light housing got so I used 2 thermocouples to observe the temperatures in there remotely. I filled all the tires up in rapid succession to get an idea of what I might expect on the trail.
Inflate times and temps:
Tire #1
Time to inflate 15psi ->35psi: 1 min 50 sec
Fuel intake temp before/after: 88° -> 88°
Tail light housing temp before/after: 88° -> 91°
Tire #2
Time to inflate 15psi ->35psi: 1 min 56 sec
Fuel intake temp before/after: 88° -> 90°
Tail light housing temp before/after: 91° -> 95°
Tires #3 & #4 simultaneously
Time to inflate 15psi ->35psi: 3 min 51 sec
Fuel intake temp before/after: 90° -> 95°
Tail light housing temp before/after: 95° -> 105°
In the end I'm happy with the set-up, for something I don't use that often it seems fit for purpose. Half the time I forget it's even there, but when you need it, it's all there ready to go. Just wanted to share one more option for onboard air in the 392.
I don’t air down often, but when you need a compressor, you need a compressor. So, I went with the single motor ARB CMK12 based on my use case. The set-up had to be:
- As hidden as possible with nothing out in the open that could be stolen when running without top/doors.
- Must including all air accessories, all securely stored onboard the Jeep and available anytime they're needed.
- I wanted the air chuck accessible outside the vehicle to keep the doors closed while airing up.
- Be able to turn on and off the compressor using a factory AUX switch
- Look as OEM as possible, like it came that way from the Factory.
It was tricky getting the mounting plate inside the body cutout then attaching the compressor. I ended up taking the compressor base plate off and pressing some stainless steel carriage bolts into the mounting plate. I then spent an hour aligning and screwing in the 4 vibration isolating bolts to re-attach the compressor inside the body. I ran the wiring down to the frame, then though the frame and up into the engine bay. For the plumbing I used ARB’s 3-ft braided stainless steel PTFE hose and cut a hole in the fuel housing to mount an ARB hose coupling with dust cap. I was very careful to route the hose as far away as possible from any wires or fuel line as this hose will get very hot. There is a JL fuel door with air fitting available but I just mounted it directly to the fuel door housing. When you filling-up you can't even see the air fitting, and it is not in the way of the gas cap. Which is important because the 392 likes gas.
The ARB wire harness is not very long, so I bought 2 spools of 8 gauge wire (red & black) to connect the compressor to the battery, and 2 spools of 18 gauge wire (red & black) to connect the 40A relay to the negative of the battery terminal and the factory AUX #2 to turn on the compressor from the cabin. There is a great video on the Wayalife youtube channel explaining how this all works. I used inline soldered splice to "lengthen" the ARB wire harness to reach the engine bay. After that I used some automotive heat shrink tubing and some Tesa tape to wrap it all up.
Finally in the engine bay I used an inline splice on the red 8 gauge + wire to reattach the 40A ARB fuse. I ran all the wire up from the frame and inside the wire track (chase) along the firewall. Then I used a ARB fuse bracket from American Adventure Lab to secure the 40A fuse to the firewall, and I connected all the wires. I wanted the run from the battery to the fuse to be as short as possible so being able to attach the fuse to the firewall with a bracket was very helpful, plus the bracket was very well made by AAL.
Finally I need to add the air accessories. I picked up a couple air hoses. I shortened the Flexzilla hose to allow it to nest inside the longer hose. I added a pair of Haltec H-5265 lock-on air chucks, and I built a 3-way manifold to allow two tries to be inflated simultaneously. I also added an old Milton inflator and CH tire gauge I had lying around. I wanted to keep everything standard ¼” brass industrial couplings for reliability and compatibility. I ordered some deflators from an Aussie company called iCheck TPMS which work great and hit the target pressure of 15psi within ½ a psi. Everything is designed to fit into the space used by the jack, easy to access and most importantly always available onboard the Jeep. And the plastic cover fits over it keeping everything nice and clean.
So with it all set-up it was time to test it out. I went ahead and timed everything. I used the iCheck TPMS to deflate.
Deflate:
All 4 tires simultaneously:
- 35 psi -> 15 psi took: 3 min 25 sec
To air back up I did one side filling each tire individually. On the other side I filled both tires at once using the 3-way valve. I was curious if the times would be any different. They ended up about the same.
I also wanted to monitor how hot the compressor got and how hot the fuel intake and the tail light housing got so I used 2 thermocouples to observe the temperatures in there remotely. I filled all the tires up in rapid succession to get an idea of what I might expect on the trail.
Inflate times and temps:
Tire #1
Time to inflate 15psi ->35psi: 1 min 50 sec
Fuel intake temp before/after: 88° -> 88°
Tail light housing temp before/after: 88° -> 91°
Tire #2
Time to inflate 15psi ->35psi: 1 min 56 sec
Fuel intake temp before/after: 88° -> 90°
Tail light housing temp before/after: 91° -> 95°
Tires #3 & #4 simultaneously
Time to inflate 15psi ->35psi: 3 min 51 sec
Fuel intake temp before/after: 90° -> 95°
Tail light housing temp before/after: 95° -> 105°
In the end I'm happy with the set-up, for something I don't use that often it seems fit for purpose. Half the time I forget it's even there, but when you need it, it's all there ready to go. Just wanted to share one more option for onboard air in the 392.
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Funny you should say that. I do a lot of work on my old house (1830's) and I started a YouTube channel just to share how to do old house stuff like leveling a wonky subfloor floor, building a custom Shaker kitchen from hard Maple, HVLP finishing. I did it just cuz i couldn't find good, accurate info on youtube from people that actually had done this stuff. I turned down the monetization option because I didn't want to deal with the tax headaches. (I've made enough on GOOGL). I tried to help answer peoples questions on there but things just started to get away from me and 1.2 million views later I abandoned the channel. It was taking too much time and started to feel like work. I've thought about doing a Jeep video on there, but I prefer this 392 forum. I'm talking to a nice group of folks on here that enjoy their 392's and it's just fun. YouTube felt like a job, and to quote Office Space "I don't like my job and I don't think I'm gonna go anymore."
