Install: ARB Twin Compressor for 4th Gen Rams

[mtrewartha]

I just finished up installing an ARB Twin Compressor in my 2013 Ram 3500 Mega, so I thought I'd share some lessons learned and provide some instructions on how to replicate what I did. My exact setup won't work for everyone since my compressor is located behind my back seat (which requires a Mega Cab), but it should work for some and others can adapt it to their needs.

First of all, it's worth mentioning that there are a few places I could find that would've been suitable to this thing, depending on the climate you live in and the terrain that you frequent:

• Inside the bed, mounted to either the side or the front: This option might be nice for some folks, depending on how you use your bed. The thing I didn't like about this spot was that it's exposed when you've got stuff filling your bed... I'm talking firewood, rocks, dirt, or even things like storage bins. I just didn't want to worry about using my bed the way it was intended to be used, so this wasn't the option for me.
• Between the bed and the bed sides: This option is pretty good if you don't live in a climate with harsh road conditions and/or don't plan on taking your truck for swims every so often. I live in Colorado and plan on moving back to Minnesota, where there are pretty harsh road conditions in the winter. Salt, mag chloride, sand, ice, etc... are all hazards I didn't want to expose the compressor to.
• Behind the DEF tank: This was a no go for the same reasons as above.
• In the storage bin behind the back seat: This was the option I chose, but it's worth mentioning that it requires cutting out the front of the bin to allow for fitment and ventilation. The biggest reason I chose this spot was protection. I don't have to worry about water, snow, ice, salt, mag chloride, rocks, or anything else hitting the compressor and ruining it over time. Plus, it always has a clean, cool, fresh air supply from under the back seat. When heat's a concern (the temp of the compressor itself), you can simply lay the back seat forward and flip the storage bin open to expose the compressor even more.

I'm sure there are more, but these were the most obvious ones that presented themselves to me. Anyways, here are the steps I took! These will be coming in multiple posts, just FYI.

 

[mtrewartha]

Step 1: Prepare the Storage Bin for the Compressor and Manifold

The driver side of the storage bin is a pretty perfect space for the compressor and manifold, provided you're comfortable cutting the front of the bin out. Here's how you do it:

1. Take out the 3 x 10mm bolts that secure the bin. There's one on the driver side, one in the middle, and one on the passenger side.
2. Open both compartments and use them to lift the bin out. You might have to pivot the spring-loaded seat flaps back a bit in order to worm the bin out. NOTE: If you've got the Alpine sound system, be sure you disconnect the wires on the passenger side that feed the subwoofer.
3. Clear out the driver side compartment. Test fit the compressor in the compartment so you can get an idea of how it fits in there. Check out my picture below to see the orientation.
4. Using a Dremel with cutoff wheel (or similar tool), carefully trim out the front of the driver side compartment. I just eyeballed this, but I went VERY slowly, taking my time to make sure that I got things straight. I cut out just enough of the bin to allow good airflow around the compressor. That thing gets hot, so we need it to be able to ventilate. That said, we need to keep enough material to let the bin stay structurally sound. Keep in mind that you can't mount the compressor all the way on the driver side, either. You can't cover up the hole for the bolt that holds the bin in. If you're mounting the manifold in the bin as well (that's what I did, it fits quite nicely), make sure to leave enough room on the left side of the compressor to mount the manifold in the same compartment. When you're done clean up the edges with some sandpaper or a grinding stone in your Dremel. Sharp edges suck.
5. Now, flip the bin over and tape the ARB-supplied template to the right spot on the bottom of the bin. Drill through the template and the bin with a bit that matches the template hole sizes (can't remember what I used here, but I think it was a 9/32" drill bit.
6. Now's a good time to do the same for the manifold. Use the brackets supplied with the manifold as your template.
7. Before you get all excited and bolt this bad boy compressor into the bin, you need to adjust the angle of the compressor output port so that the 90* elbow on the stainless steel hose fits under the bin lid. Follow the ARB instructions for this part... angle the output port towards the side of the compressor that you're mounting the manifold on.
8. Alright, NOW you can bolt the compressor in! Don't crank too hard on the bolts and make sure you use the supplied washers. We're dealing with plastic here, so we don't want to break it.
9. Let's assemble the manifold and orient the manifold ports correctly so we can get it bolted in. Follow the instructions in the kit to do this. I oriented the NPT ports (on the end caps) straight up. I have air lockers, so I needed the solenoids installed as well. I oriented the solenoid ports up and to the right at a 45* angle so that the air hoses coming out of the solenoids (for the lockers) don't have to turn too sharp or get too close to the compressor.
10. Bolt the manifold in! Again, be careful and don't go too tight on these bolts... don't wanna break the plastic bin and you can get them plenty tight enough to hold the manifold in securely without going too tight.
11. Work the storage bin back into position in the truck.
12. If you're NOT running air lockers, continue to the next step. If you are running them though, you need to drill a hole down, through the bin and floor of the cab. Placement of this hole is critical. There's a U-shaped channel of sheet metal that supports the underside of the cab. You're going to drill your hole a few inches back from the bolt hole on the far right (driver) side of the bin. The goal here is to get your hole inside the channel under the cab. If you peek at the channel from the bottom of the truck, you'll notice a square hole. It's right below where your hole should be. If you drill your hole correctly, you can feed your air lines down through it, then through that square hole. I screwed this up haha, so I improvised, as you'll see in the picture below. Anyways, drill the hole through the bin, the sound-deadening material beneath it, and the cab.
13. Once you've drilled through, vacuum all of the plastic out of the bin, then pull the bin back out of the truck.
14. Using your Dremel, file, or some other tool, clean up the metal in the hole. You want to get rid of all of the sharp edges so they don't cut through your air lines over time.
15. Spray the hole with some primer, paint, or even better, some rubberized undercoating. Whatever you use, make sure you get a couple light coats on. Give them sufficient time to dry and DO NOT rush this... the last thing you want is rust forming where you drilled through. While you're waiting for things to dry, you can run some of the wiring.

I'll come back and write the rest later! Dinner time :elkgrin:

 

[Marine]

Thank you, have a 3rd gen and was thinking bout this in near future.

 

[mtrewartha]

No prob!

 

[mtrewartha]

Step 2: Run the Wiring

You're going to run two sets of wires here: the switch wiring to control the compressor and locker solenoids, along with the two power cables and one ground cable for the compressor.

1. If you've chosen the same mounting location as I did, you'll have to extend the power harness that comes with the compressor. Follow the instructions in the kit: use the same or larger gauge wire, solder the joints together, use good heat shrink, and make sure you extend on the side closest to the compressor, since the inline fuses that ARB supplies need to be next to the battery. RUN THE EXTENSION THROUGH THE FIREWALL BEFORE YOU SOLDER THE CONNECTIONS. The connectors are too big to fit through the firewall. Under your steering wheel, there should be a spot where a big bundle of wires already runs through the firewall. Cut a new hole on that rubber seal and sneak the wires through.
2. After you've extended the power harness, pop some ring terminals on the battery-side ends and get them wired up to the battery according to the ARB wiring diagram.
3. Run the wires under the trim along the driver side kick panel, the door jam, the bottom of the B pillar, and the rear door trim. It should come out of the trim behind the back seat, right by where your new storage compartment opening will be when you put the bin back in. You'll probably have to pop the trim out along the way to get the wires to lay nicely inside. Don't worry, it's quite easy to pop back into place. Before you do, though, run the switch wiring in the same spot. It was long enough to use in my Mega without any modification.
4. Pop out the panel where you'll mount the switches. It's right above the parking brake release lever. There are 4 clips, 1 in each corner of the panel. Squeeze and pop out each of them. If you pop out the top two, you can pry the panel carefully and the bottom two will pop out as well.
5. Now you need to cut out the opening for the switches. Again, I eyeballed this and took my sweet, sweet time with a Dremel cutoff wheel. Make sure that you place the opening in the middle of the panel. When you push the switches through your opening, they can't block the clips that hold the panel into the dash. That said, cut the correct size opening depending on how many switches you have and how you want to mount them. I wanted all three of mine right next to each other, so I cut out one large opening that fit all three.
6. Don't pop the switches into the panel yet. Connect the wiring up to the switches according to the ARB diagram.
7. Find a keyed power source wire (I used the round 12V power outlet's positive wire) and tap into it with the wire specified in the ARB instructions (I think it's red and yellow).
8. If you want the lights dimmed, then tap a dimmed wire as well. I didn't care about this because I'm never driving for long distances at night with the compressor or lockers turned on. I just tucked the wire up and out of the way with a zip tie.
9. Connect the switch wiring to the harness that you ran under the trim back to the compressor.
10. Alright, you're ready to pop the storage bin back in, provided the paint or whatever you used is dry around the hole you drilled through the floor. Pop open the lids on the compartments and lay the bin back into its spot. If you've got the Alpine sound system with the subwoofer, connect that wiring again. Once you've laid it, put the 3 bolts back in to secure the bin.

 

[mtrewartha]

Step 3: Run the Air Lines

1. Push the end of each air line into the locker solenoids. These are push lock fittings, so push the air line all the way in and it will not be able to pop back out. Tighten the fittings once you know you've got the air lines far enough in.
2. Run the other end of each air line out of the bin, through the hole you drilled. Fish it through the square hole in the cab, too.
3. Once you've got the lines out of the cab, start running them along the frame rails, brake lines, etc... as shown in my pictures below. Make sure you use zip ties. LOTS. OF. ZIP. TIES. You want these lines to be safe and secure so they don't rub and break open over time. In addition, they keep lines nice and clean looking.
4. Once you've got the lines routed to each axle, make sure you leave enough line for axle articulation. Your axle will move up and down while you're offroad obviously, so you need to make sure there's enough air line to accommodate and flex with the suspension without yanking the air lines out of the bulk head fittings on your axles. As a general rule, you'll be fine if you mimic the length of your brake lines. Clip your air lines to the right length.
5. Slide the little springs and bulkhead nuts onto your air lines, then pop the ends of the air lines onto the bulkhead fittings for your air lockers that pop out of the axle housing.
6. Tighten down the bulkhead nuts and they'll suck the air lines down fully onto the fittings. Lastly, slide the springs down over the bulkhead nuts.
7. Verify everything works! Read your air locker and compressor instructions so you know about any gotchas, when to run them and when to not run them, etc... Seriously, don't skip this step!
8. Crack open a cold, tasty beverage of your choice and enjoy.

ALL DONE. Enjoy your new onboard air compressor and lockers!

 

[smlobx]

Very nice write up!
I saw the ARB folks at Expo East and they had a similar set up in a Super Duty. I will be trying to copy that setup when I get to it.
One question...are you going to install an air tank or have a port for filling your tires?

 

[mtrewartha]

Thanks, hopefully it proves helpful!

I've thought about both... If I do either of them, it won't be for awhile. I filled up all 4 of my tires tires the other day (37" tires from 20 to 55 PSI) and it was so easy as is. All I have to do to access my manifold is flip down the back seat and pop the storage bin open... relocating that port to the bed, bumper, or anywhere else wouldn't achieve a whole lot, especially if I have to get behind my back seat to grab the air hose anyways.

That said, the air tank might provide a nice buffer. The pump was able to inflate my 37s, but it took 10-15 mins. Having a tank doesn't mean the pump has to compress any less air to fill the tires, but it might still be nice to be able to choose how much air I hold on to and it'll enable the compressor to run a tad less often. A tank would be nice for running air tools on the trail as well, but that would be quite a rare occurrence. In addition, my impact wrench would blow through that small of a tank in no time flat... even with the 33 gallon tank in my garage sitting at 150 PSI, it doesn't taken long for the impact wrench to drain it.