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Haven't seen any posts about installing the new ARB brushless twin compressor with the SDHQ mount so thought I'd share what I have done and maybe some tips. This isn't a how to post, as the instructions that came with the SDHQ mount was pretty straight forward. I just think pictures are worth a thousand words.
There are many horizontal ARB mounts available from different vendors. They all seem to mount the same way, from the passenger fender wall and with a support piece attached to the front shock mount. The one that I came close to getting was the KR mount because out of all of them it was made of stainless steel and it supported the brushless ARB without any modifications. However, I just didn't like the idea of using a shock mount for support, I'm sure it works, but just not for me.
That led me to look into vertical mounts. They look more OEM and appear to take up less space than the horizontal mounts. The Grimm Offroad mount seem pretty good and has lots of nice reviews. But I didn't like it because again it relied on the shock mount. It also does not support the brushless ARB, but it can if some simple drilling of mounts were made. This led me to the SDHQ mount, it's a pretty simple mount that didn't require putting the ARB in a cage with a bunch of screws like the Grimm mount. The SDHQ mount also does not support the ARB brushless twin or at least I have never read about anyone doing it. Recently SDHQ did come out with an adapter such that you could now mount an ARB brushless twin with most of their existing ARB twin compressor mounts. Although this sounded great, it increases the cost of the mounting solution. The SDHQ mount is about $280.00 and add the adapter was another $100.00 so I can see why the SDHQ may not be on anyone's top list. In any case after investigating as much as I could, I decide to go with just the SDHQ mount with no adapter and just make it work. The Northridge 4x4 YouTube video gave me a good idea on the physical differences between the brushless and brush motor and the only concern was the height.
This is the main SDHQ mount where the ARB brushless twin adjustable adapter is bolted on, this adjustable thingy worked out great. It turns out with all the bolts I had prepared at hand; I wound up only using a combination of the bolts, washers and nuts that came with the ARB and the SDHQ kit. I DID NOT have to drill anything or use any extra hardware, it just fit.
This is the other side of the mount, and you can see 5 nuts and bolts, 4 of them hold the ARB and 2 (1 from the 4 bolts is dual purpose) are used to hold the firewall support bracket. The instructions show using 1 bolt for the firewall bracket, but I manage to also use 1 of the 4 bolts so that there are 2 mounting points to the firewall support bracket. Keep in mind the SDHQ instructions were meant only for the ARB twin compressor. To my surprise it turns out the SDHQ mount can support the ARB brushless twin compressor with no modifications at all. The only trick is you have to use a combination of hardware that came in both the ARB and SDHQ box.
It fits perfectly and you can see they give you spacers; the ECU is not flat against the mount itself. I guess it does 2 things, it keeps the nuts from hitting the ECU and keeps the heat away. No modifications were made. The mount is so solid I could rock the bronco with it and thought about not even bothering to mount the firewall bracket. BTW I didn't even bother to disconnect the cable from the ECU, just left it on and bolted it all to the main mount. Yea I disconnected the battery though.
For the 2 ground wires the instructions say to bolt them to the firewall, I chose to bolt them to the fender bracket because that's where the ECU ground was bolted to so it must be good (LOL). If you use the original bolts that held the ECU bracket you will have to sand down underneath the flange bolt to get to the bare metal for a good ground connection. I used some other ground bolts I had lying around, yea I know the bracket is powder coded, but I measure 0.1 ohms from that ground connector back to the negative of the battery cable so I'm good. The ground point on the firewall also measured 0.1 ohms to the negative battery cable.
This is the wiring mess. You will have to hack the stock wiring harness down a bit because a lot of it you won't use. There is an excellent wiki on this subject by MileHighWT. I heard so much about how much heat these things give off that I made sure to keep everything away from the ARB. The power connectors are zip tied to one of those VHB taped zip tie anchor thingy on the air intake box. The brownish sleeves are silicon coated fiberglass heat shields, one is for the pressure sensor wires, the other is covering a 1.5M 1/4" JIC female 04 stainless steel braided PTFE hose. The 2 positive cables are sleeved in a high temperature split nylon wire loom. Nothing touches the ARB body. Overkill, heh?
This is underneath the ARB. You can see the pressure sensor connector and the shiny 90-degree JIC 04 fitting. There is enough space underneath for air when the twin fan motors turn on.
This is how low you want the ARB to sit. Do not mount it higher than the top screw that holds the ECU, otherwise the Broncos hood lining (if you have them) will hit the ARB filters. This was why I was concern that the ARB twin brushless was taller than the brushed version, but because the ARB brushless twin has a sliding mount, that came in handy in adjusting the height to where I needed it to be. It made me wonder if the SDHQ adapter mount for the brushless would work because they don't use the sliding mount, its statically mounted. Well, they make good products, so I assume their engineering dept checked it out.
Positive cable connection, I used the battery accessory stud away from the engine, so you need get a 6mm flange nut. I didn't have one lying around so I used one of the original flange nuts that held down the ECU, its black oxide, I'll change it to stainless steel later. The red positive cables are hooked up to 2 60A fuses and I mounted them using VHB to the side of the battery box. I also flipped around the cables in the fuse box so the cover holes were on the bottom, if you do that don't forget to change the bus bar in the fuse box also, the bus bar should be facing the battery.
In any case I was thinking of installing a switch in series with the "Red" wire to use it as another cutoff switch, but it turns out for some reason, the switch that comes with the ARB brushless twin compressor does not fit the rectangular hole on the SDHQ firewall bracket, it's too small, go figure. Maybe I'm doing something wrong? I will have to file down the hole a bit if I want to use that switch.
I made a coupling bracket using rectangular tubing from a scrapped NordicTrack I found on craigslist. The bracket bolts right up to the KR fog light mount I already had.
The redline hood struts fit with no issues when closing the hood.
There are many horizontal ARB mounts available from different vendors. They all seem to mount the same way, from the passenger fender wall and with a support piece attached to the front shock mount. The one that I came close to getting was the KR mount because out of all of them it was made of stainless steel and it supported the brushless ARB without any modifications. However, I just didn't like the idea of using a shock mount for support, I'm sure it works, but just not for me.
That led me to look into vertical mounts. They look more OEM and appear to take up less space than the horizontal mounts. The Grimm Offroad mount seem pretty good and has lots of nice reviews. But I didn't like it because again it relied on the shock mount. It also does not support the brushless ARB, but it can if some simple drilling of mounts were made. This led me to the SDHQ mount, it's a pretty simple mount that didn't require putting the ARB in a cage with a bunch of screws like the Grimm mount. The SDHQ mount also does not support the ARB brushless twin or at least I have never read about anyone doing it. Recently SDHQ did come out with an adapter such that you could now mount an ARB brushless twin with most of their existing ARB twin compressor mounts. Although this sounded great, it increases the cost of the mounting solution. The SDHQ mount is about $280.00 and add the adapter was another $100.00 so I can see why the SDHQ may not be on anyone's top list. In any case after investigating as much as I could, I decide to go with just the SDHQ mount with no adapter and just make it work. The Northridge 4x4 YouTube video gave me a good idea on the physical differences between the brushless and brush motor and the only concern was the height.
This is the main SDHQ mount where the ARB brushless twin adjustable adapter is bolted on, this adjustable thingy worked out great. It turns out with all the bolts I had prepared at hand; I wound up only using a combination of the bolts, washers and nuts that came with the ARB and the SDHQ kit. I DID NOT have to drill anything or use any extra hardware, it just fit.
This is the other side of the mount, and you can see 5 nuts and bolts, 4 of them hold the ARB and 2 (1 from the 4 bolts is dual purpose) are used to hold the firewall support bracket. The instructions show using 1 bolt for the firewall bracket, but I manage to also use 1 of the 4 bolts so that there are 2 mounting points to the firewall support bracket. Keep in mind the SDHQ instructions were meant only for the ARB twin compressor. To my surprise it turns out the SDHQ mount can support the ARB brushless twin compressor with no modifications at all. The only trick is you have to use a combination of hardware that came in both the ARB and SDHQ box.
It fits perfectly and you can see they give you spacers; the ECU is not flat against the mount itself. I guess it does 2 things, it keeps the nuts from hitting the ECU and keeps the heat away. No modifications were made. The mount is so solid I could rock the bronco with it and thought about not even bothering to mount the firewall bracket. BTW I didn't even bother to disconnect the cable from the ECU, just left it on and bolted it all to the main mount. Yea I disconnected the battery though.
For the 2 ground wires the instructions say to bolt them to the firewall, I chose to bolt them to the fender bracket because that's where the ECU ground was bolted to so it must be good (LOL). If you use the original bolts that held the ECU bracket you will have to sand down underneath the flange bolt to get to the bare metal for a good ground connection. I used some other ground bolts I had lying around, yea I know the bracket is powder coded, but I measure 0.1 ohms from that ground connector back to the negative of the battery cable so I'm good. The ground point on the firewall also measured 0.1 ohms to the negative battery cable.
This is the wiring mess. You will have to hack the stock wiring harness down a bit because a lot of it you won't use. There is an excellent wiki on this subject by MileHighWT. I heard so much about how much heat these things give off that I made sure to keep everything away from the ARB. The power connectors are zip tied to one of those VHB taped zip tie anchor thingy on the air intake box. The brownish sleeves are silicon coated fiberglass heat shields, one is for the pressure sensor wires, the other is covering a 1.5M 1/4" JIC female 04 stainless steel braided PTFE hose. The 2 positive cables are sleeved in a high temperature split nylon wire loom. Nothing touches the ARB body. Overkill, heh?
This is underneath the ARB. You can see the pressure sensor connector and the shiny 90-degree JIC 04 fitting. There is enough space underneath for air when the twin fan motors turn on.
This is how low you want the ARB to sit. Do not mount it higher than the top screw that holds the ECU, otherwise the Broncos hood lining (if you have them) will hit the ARB filters. This was why I was concern that the ARB twin brushless was taller than the brushed version, but because the ARB brushless twin has a sliding mount, that came in handy in adjusting the height to where I needed it to be. It made me wonder if the SDHQ adapter mount for the brushless would work because they don't use the sliding mount, its statically mounted. Well, they make good products, so I assume their engineering dept checked it out.
Positive cable connection, I used the battery accessory stud away from the engine, so you need get a 6mm flange nut. I didn't have one lying around so I used one of the original flange nuts that held down the ECU, its black oxide, I'll change it to stainless steel later. The red positive cables are hooked up to 2 60A fuses and I mounted them using VHB to the side of the battery box. I also flipped around the cables in the fuse box so the cover holes were on the bottom, if you do that don't forget to change the bus bar in the fuse box also, the bus bar should be facing the battery.
The 2 red positive cables were sleeve in nylon split tubing. The "Red" wire, which really controls the pressure switch by giving it juice, was hooked up to an upfitter switch. I know some people like to just hookup a switch next to the ARB instead of using upfitter switches. Some folks hookup the air hose and turn the switch on from the engine compartment and say they don't like having to push the accessory button just to use the air compressor. I think you need to turn the engine on otherwise your battery could drain (unless you have some dual batt setup) so might as well use the upfitter switch. 
In any case I was thinking of installing a switch in series with the "Red" wire to use it as another cutoff switch, but it turns out for some reason, the switch that comes with the ARB brushless twin compressor does not fit the rectangular hole on the SDHQ firewall bracket, it's too small, go figure. Maybe I'm doing something wrong? I will have to file down the hole a bit if I want to use that switch.
I made a coupling bracket using rectangular tubing from a scrapped NordicTrack I found on craigslist. The bracket bolts right up to the KR fog light mount I already had.
The redline hood struts fit with no issues when closing the hood.
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