ARB single compressor install , the painful way .

Hello Team,
So ever since I got the Gren I identified the area behind the aux battery as the perfect place for an air compressor. I think the engineers were thinking the same since the extra wiring was also present there.

Now this is one way to do it. This is the painful, weird and masochistic Tinki way of doing it.
I bet more clever people will find a better way.
Disclaimer I am not a sparky, machinist or engineer, I know that I know nothing and the little I know makes me dangerous, I have no issue breaking my own stuff because that is how I learn.
If you replicate the below you do so at your own risk. Any professionals reading please free to chime in. Any advice, comments and observations welcomed.

This project was done over the last month in between work and waiting for parts. A lot of failed porotypes and changes of plans because I simply try things and see how they fit until I find a problem then adapt and rinse and repeat.
I will try and mention the failed attempts so hopefully I can save you some time.

Compressor installed is an ARB CKMA 12 .

This will be divided into 3 parts: Compressor install, electrics, air coupler install

So here it goes:

What I wanted:

1)Minimal to no modification to the existing fabric of the Gren (I wanted to be able to go back to square one with no need for repairs)

2)Clean install + Tidy wiring

3) Access to the air without lifting the rear seat.


Compressor install:

First issue was the mounting of the compressor in the Gren . After looking at the area there are 4 M8 studs welded to the floor . First issue was that they are of different length and the floor Is not flat.

Second issue there is no way I found that I could directly bolt the compressor to the studs , because the bolt pattern was different . So a bracket had to be made to make a level platform to start from .

Material of choice is aluminium (Soft + light + easy to drill and finish with hand tools )

In order to transfer the studs to the plate I used CAD ( Cardboard Aided Design ) and M8 coupling nuts with M8 set screws .


The coupling nuts were screwed onto the studs, then the set screws on top and then the cardboard pressed on top to transfer the indentation of the set screws .


Then the holes were transferred to the aluminium.


Because I had no idea where the mounting bracket of the compressor itself would line up I had to make sure the whole platform was flat with no protrusions . So no hex head bolts could be used. Options were cap head screws (too thin material to countersink them, plate is 6mm ) or countersunk Allen heads which was my choice .



Before mounting the plate thought I wanted to isolate the vibration of the compressor form the Gren so I bought some rubber spacers from amazon, I glued a thick washer on the side that would mate to the coupling nuts and installed the plate.





After that it was time to identify where the compressor would actually sit. I took the mounting plate off the compressor to be able to quickly decide where it would go. I decided in the vertical orientation.

Outline was marked and holes were drilled and tapped for M6 flanged button head screws. (Tried to use rivnuts but even with the biggest ones I had due to the thickness of the plate they would pull out on exertion of force.)


Once the base is screwed to the palatform , to get the compressor mounted the aux battery needs to come out . ( You might be able to do it if you have delicate hands or extra joints but would not recommend it )

This task was only possible with the following 2 tools: My trusty Victorinox small ratchet and my ¼ Facom ratchet that works by twisting the handle instead of moving it up and down ..


This sorts the compressor mounting. On to the next bit .



Electrics :

Now you do not need to do as I did. The wiring harness that comes with the compressor is perfectly adequate. But by OCD would not allow me to use it. So I simplified it and made a new one from scratch . If you are doing the same I would suggest you get all quality parts from industrial suppliers I used Mouser they have everything you need but their search function is useless. If someone wants exactly what I bought I can share my order list. I found this to be the cheapest way of doing it.

Wiring used is all 10 AWG silicone .

So first thing I needed to do was terminate the Gren wiring. I used a hooked Stanley style blade to remove the heat shrink.



I was looking for 40amp rated connectors but could not find anything reasonable to use (I know DT has some but hey are for a single wire and way too bulky). So currently on the hunt.

Because I hate project creep and drag I decided to go with Anderson power pole connectors with future plans to change them down the line.


Can only attach 10 files . SO part 2 coming .

So cables crimped and connectors installed on the Gren .
Then comes the side of the compressor ( I de-pinned the original connector and used Anderson again )
The fact that the Gren already had a fuse for this circuit I omitted mine from my pig tail . I used a 40 amp 12 v relay to control the compressor and a switch.

I used a relay that can me mounted on the Gren ( a lot of spare studs on the vertical part of the floor . ( tried mounting a relay base initially to be easy to change the relay if needed but due to the space constraint and the length of the studs it did not work , tried also a coupling nut and button head screw also did not work to my liking )

Location of Relay.


The last bit is the switch I wanted this to be accessible without needing to lift he rear seat . so I decided to mount it with the air coupler. Will discuss this at the next bit.

Because I wanted to be able to use the air compressor with the Gren off I ignored the ignition wire. to avoid accidental activation (and for cool factor , could not resist) I used a covered switch .

To finish the harness I wrapped it with the finest quality chinesium tape ( could not find my tesa tape ) most likely someone nicked it . my brother insisted it was not him that turned out to be a lie, anyway .

Finished product comparison between my harness and the original supplied by ARB .




Crimps used for the Anderson connectors : EDIT : Previous advice was to use No 13 crimp die . Have now discovered that No 05 yields better results . Apologies for the mistake .



Air quick coupler + switch install :

Now this was a real head scratcher, almost came close to saying duck it and drilling a hole on the battery “box” but instead I cracked open a cold one and revisited it the next day.

So my solution to this is a bracket fabricated to attach with M10 sleeve nuts on the seat backet . Here I was playing with Millimetres very very annoying due to the proximity of the seat to the battery box . But its doable.





The bracket sits on the shelf on the left and extends up to the edge of the seat. I made sure there was enough clearance when lifting the seat and nothing was rubbing .

To connect the compressor to the palate I thought of 2 options. The easiest of the 2 is to use push in fittings and PTFE air line. The other is to use stainless braided PTFE lined hose . I opted for the second hoping that it will help dissipate some heat form the system .


Now the outlets of the compressor are 1/8 NPT for the manifold silver bit and ¼ NPT for the black bit . I used an 1/8 NPT pressure switch on the manifold because of my future plans instead of the supplied ¼ NPT.

I decided to keep everything NPT and use the ARB couplers (They are US standard, might make an adaptor or change them later).

Connection is as follows SS braided line from compressor (in the future a T will be placed there to plumb the other side) that goes to the aluminium plate.

At the plate connection it would make sense to use an elbow but my plate was too thick for that so I opted for a bulkhead fitting and a 90 degree elbow .

Then the ARB quick coupler simply threads in. (I checked it does not interfere with the door or you legs)

The switch had to be mounted on the other side because there is simply no space.

Again this could be very easy if you are happy to drill the battery box. IF you do it the way I did just know there is minimal to no margin for error ( I have a lot of scrap aluminium prototypes to prove it )



Future plans:

1)Second air coupler on the left-hand side of the car with its own switch.

2)Professional made and anodised brackets. (Always good to know a machinist)

3) Third air coupler at the back of the car.

4) wiring revision for all watertight connectors (on the hunt for 40Amp 2 wire connectors that are not larger than the compressor itself + a delphi relay base)



That is all guys

Thank you hope you enjoyed. please feel free to share your installs.

Last bit to mention , SS line was wraped with tape to avoid contact wiht battery terminal and i am on the look out for a terminal cover i know DCPU has found one that fits , will aim to get one of those also .

Tinki said:

Last bit to mention , SS line was wraped with tape to avoid contact wiht battery terminal and i am on the look out for a terminal cover i know DCPU has found one that fits , will aim to get one of those also .

Click to expand...

I'd cable tie that braided line WAY out of the way of that + terminal, in fact I'd even put a cap on the post

Admire your work and fabulous documentation, well done. My only concern would be how hot these compressors get when you air up 4 tyres. Would be somewhat concerned in that enclosed space under the seat and beside the battery which don’t love heat.

MrMike said:

I'd cable tie that braided line WAY out of the way of that + terminal, in fact I'd even put a cap on the post View attachment 7825462

Click to expand...

Yeah i know you are right . It is well above and now its wraped with harness tape on the seat tube skeleton . But you are right i am getting a terminal cover asap , i will find the one that fits .

AnD3rew said:

Admire your work and fabulous documentation, well done. My only concern would be how hot these compressors get when you air up 4 tyres. Would be somewhat concerned in that enclosed space under the seat and beside the battery which don’t love heat.

Click to expand...

Thank you for your kind words Andrew .
And you are right about the heat but i had to make a compromise somewhere . Having a look through the car the only other space for the air compressor to go was on the left hand side panel in front of where the jack is stored . But i am saving that space for my inverter which will get way more use and will produce way more heat .
I had a good think about it and decided to risk it . My thought process was that the compressor will be used on trips and the temperature spikes will be short lived . The other bit that thought might help was the fact that i used 5mm aluminium plate and ss lead hose to connect the compressor to the coupler i hope the plate will act as a big heat sink .

I agree this is not an ideal position for a compressor for someone who uses it all the time .
But for me airing up and airing down tires once or twice a day on a week long trip I believe is acceptable.

Tinki said:

Last bit to mention , SS line was wraped with tape to avoid contact wiht battery terminal and i am on the look out for a terminal cover i know DCPU has found one that fits , will aim to get one of those also .

Click to expand...

Excellent work.

My terminal cover is not a *perfect* fit, as I've yet to see a right angle down cover, but it more than does the job:

DCPU said:

Excellent work.

My terminal cover is not a *perfect* fit, as I've yet to see a right angle down cover, but it more than does the job:
View attachment 7825469

Battery Terminal Covers: Polevolt Ltd

Car battery terminal covers, large selection of single bolt terminal covers and battery hold down clamps.

polevolt.co.uk

View attachment 7825471

Click to expand...

Much appreciated. I will have a look around and see what exists . I might pop into a battery retailer and ask if they have any special covers . To be fair the way the terminal is oriented is a bit weird never seen something like it . Other option is a custom one ? Do they even make custom ones ? Xmmm ……

@Tinki ~ keep us posted.

Will do .

Very impressive, I don't need a compressor, but your write up, like others on this Forum convince me I do!

Trialmaster said:

Very impressive, I don't need a compressor, but your write up, like others on this Forum convince me I do!

Click to expand...

Hahahah thank you my friend .
I think we are a bad influence on each other .
I am in the same boat with the D250SE which is next on the list to be installed .

DCPU said:

@Tinki ~ keep us posted.

Click to expand...

On my quest for battery terminal covers I stumbled upon these guys .



It might be a viable option if all of us order a couple .

DCPU said:

Excellent work.

My terminal cover is not a *perfect* fit, as I've yet to see a right angle down cover, but it more than does the job:
View attachment 7825469

Battery Terminal Covers: Polevolt Ltd

Car battery terminal covers, large selection of single bolt terminal covers and battery hold down clamps.

polevolt.co.uk

View attachment 7825471

Click to expand...

Hint hint.... Assemble/sell a pre-packaged kit of all the covers and everything you've done to the under-seat area

anand said:

Hint hint.... Assemble/sell a pre-packaged kit of all the covers and everything you've done to the under-seat area

Click to expand...

Not actually started that project yet...got distracted when sourcing parts...

Tinki said:

Hello Team,
So ever since I got the Gren I identified the area behind the aux battery as the perfect place for an air compressor. I think the engineers were thinking the same since the extra wiring was also present there.

Now this is one way to do it. This is the painful, weird and masochistic Tinki way of doing it.
I bet more clever people will find a better way.
Disclaimer I am not a sparky, machinist or engineer, I know that I know nothing and the little I know makes me dangerous, I have no issue breaking my own stuff because that is how I learn.
If you replicate the below you do so at your own risk. Any professionals reading please free to chime in. Any advice, comments and observations welcomed.

This project was done over the last month in between work and waiting for parts. A lot of failed porotypes and changes of plans because I simply try things and see how they fit until I find a problem then adapt and rinse and repeat.
I will try and mention the failed attempts so hopefully I can save you some time.

Compressor installed is an ARB CKMA 12 .

This will be divided into 3 parts: Compressor install, electrics, air coupler install

So here it goes:

What I wanted:

1)Minimal to no modification to the existing fabric of the Gren (I wanted to be able to go back to square one with no need for repairs)

2)Clean install + Tidy wiring

3) Access to the air without lifting the rear seat.


Compressor install:

First issue was the mounting of the compressor in the Gren . After looking at the area there are 4 M8 studs welded to the floor . First issue was that they are of different length and the floor Is not flat.

Second issue there is no way I found that I could directly bolt the compressor to the studs , because the bolt pattern was different . So a bracket had to be made to make a level platform to start from .

Material of choice is aluminium (Soft + light + easy to drill and finish with hand tools )

In order to transfer the studs to the plate I used CAD ( Cardboard Aided Design ) and M8 coupling nuts with M8 set screws .
View attachment 7825420

The coupling nuts were screwed onto the studs, then the set screws on top and then the cardboard pressed on top to transfer the indentation of the set screws .
View attachment 7825421

Then the holes were transferred to the aluminium.
View attachment 7825422

Because I had no idea where the mounting bracket of the compressor itself would line up I had to make sure the whole platform was flat with no protrusions . So no hex head bolts could be used. Options were cap head screws (too thin material to countersink them, plate is 6mm ) or countersunk Allen heads which was my choice .

View attachment 7825423

Before mounting the plate thought I wanted to isolate the vibration of the compressor form the Gren so I bought some rubber spacers from amazon, I glued a thick washer on the side that would mate to the coupling nuts and installed the plate.

View attachment 7825424



After that it was time to identify where the compressor would actually sit. I took the mounting plate off the compressor to be able to quickly decide where it would go. I decided in the vertical orientation.

Outline was marked and holes were drilled and tapped for M6 flanged button head screws. (Tried to use rivnuts but even with the biggest ones I had due to the thickness of the plate they would pull out on exertion of force.)


Once the base is screwed to the palatform , to get the compressor mounted the aux battery needs to come out . ( You might be able to do it if you have delicate hands or extra joints but would not recommend it )

This task was only possible with the following 2 tools: My trusty Victorinox small ratchet and my ¼ Facom ratchet that works by twisting the handle instead of moving it up and down ..
View attachment 7825425

This sorts the compressor mounting. On to the next bit .
View attachment 7825426


Electrics :

Now you do not need to do as I did. The wiring harness that comes with the compressor is perfectly adequate. But by OCD would not allow me to use it. So I simplified it and made a new one from scratch . If you are doing the same I would suggest you get all quality parts from industrial suppliers I used Mouser they have everything you need but their search function is useless. If someone wants exactly what I bought I can share my order list. I found this to be the cheapest way of doing it.

Wiring used is all 10 AWG silicone .

So first thing I needed to do was terminate the Gren wiring. I used a hooked Stanley style blade to remove the heat shrink.
View attachment 7825427
View attachment 7825428

I was looking for 40amp rated connectors but could not find anything reasonable to use (I know DT has some but hey are for a single wire and way too bulky). So currently on the hunt.

Because I hate project creep and drag I decided to go with Anderson power pole connectors with future plans to change them down the line.
View attachment 7825429

Can only attach 10 files . SO part 2 coming .

Click to expand...

Great write up thanks. On an aside.. is the +ve compressor wire permanently hot or via ignition on?

bakepl said:

Great write up thanks. On an aside.. is the +ve compressor wire permanently hot or via ignition on?

Click to expand...

hello Bakepl the wire is always live since i did noy utilize the ignition wire . Hence the use of a covered switch to minimize the chances of accidental circuit closure .

anand said:

Hint hint.... Assemble/sell a pre-packaged kit of all the covers and everything you've done to the under-seat area

Click to expand...

That is a good idea. Have to say, just ordered the +ve terminal covers, as it's quite a surprise that they are not protected.

Tinki said:

Hello Team,
So ever since I got the Gren I identified the area behind the aux battery as the perfect place for an air compressor. I think the engineers were thinking the same since the extra wiring was also present there.

Now this is one way to do it. This is the painful, weird and masochistic Tinki way of doing it.
I bet more clever people will find a better way.
Disclaimer I am not a sparky, machinist or engineer, I know that I know nothing and the little I know makes me dangerous, I have no issue breaking my own stuff because that is how I learn.
If you replicate the below you do so at your own risk. Any professionals reading please free to chime in. Any advice, comments and observations welcomed.

This project was done over the last month in between work and waiting for parts. A lot of failed porotypes and changes of plans because I simply try things and see how they fit until I find a problem then adapt and rinse and repeat.
I will try and mention the failed attempts so hopefully I can save you some time.

Compressor installed is an ARB CKMA 12 .

This will be divided into 3 parts: Compressor install, electrics, air coupler install

So here it goes:

What I wanted:

1)Minimal to no modification to the existing fabric of the Gren (I wanted to be able to go back to square one with no need for repairs)

2)Clean install + Tidy wiring

3) Access to the air without lifting the rear seat.


Compressor install:

First issue was the mounting of the compressor in the Gren . After looking at the area there are 4 M8 studs welded to the floor . First issue was that they are of different length and the floor Is not flat.

Second issue there is no way I found that I could directly bolt the compressor to the studs , because the bolt pattern was different . So a bracket had to be made to make a level platform to start from .

Material of choice is aluminium (Soft + light + easy to drill and finish with hand tools )

In order to transfer the studs to the plate I used CAD ( Cardboard Aided Design ) and M8 coupling nuts with M8 set screws .
View attachment 7825420

The coupling nuts were screwed onto the studs, then the set screws on top and then the cardboard pressed on top to transfer the indentation of the set screws .
View attachment 7825421

Then the holes were transferred to the aluminium.
View attachment 7825422

Because I had no idea where the mounting bracket of the compressor itself would line up I had to make sure the whole platform was flat with no protrusions . So no hex head bolts could be used. Options were cap head screws (too thin material to countersink them, plate is 6mm ) or countersunk Allen heads which was my choice .

View attachment 7825423

Before mounting the plate thought I wanted to isolate the vibration of the compressor form the Gren so I bought some rubber spacers from amazon, I glued a thick washer on the side that would mate to the coupling nuts and installed the plate.

View attachment 7825424



After that it was time to identify where the compressor would actually sit. I took the mounting plate off the compressor to be able to quickly decide where it would go. I decided in the vertical orientation.

Outline was marked and holes were drilled and tapped for M6 flanged button head screws. (Tried to use rivnuts but even with the biggest ones I had due to the thickness of the plate they would pull out on exertion of force.)


Once the base is screwed to the palatform , to get the compressor mounted the aux battery needs to come out . ( You might be able to do it if you have delicate hands or extra joints but would not recommend it )

This task was only possible with the following 2 tools: My trusty Victorinox small ratchet and my ¼ Facom ratchet that works by twisting the handle instead of moving it up and down ..
View attachment 7825425

This sorts the compressor mounting. On to the next bit .
View attachment 7825426


Electrics :

Now you do not need to do as I did. The wiring harness that comes with the compressor is perfectly adequate. But by OCD would not allow me to use it. So I simplified it and made a new one from scratch . If you are doing the same I would suggest you get all quality parts from industrial suppliers I used Mouser they have everything you need but their search function is useless. If someone wants exactly what I bought I can share my order list. I found this to be the cheapest way of doing it.

Wiring used is all 10 AWG silicone .

So first thing I needed to do was terminate the Gren wiring. I used a hooked Stanley style blade to remove the heat shrink.
View attachment 7825427
View attachment 7825428

I was looking for 40amp rated connectors but could not find anything reasonable to use (I know DT has some but hey are for a single wire and way too bulky). So currently on the hunt.

Because I hate project creep and drag I decided to go with Anderson power pole connectors with future plans to change them down the line.
View attachment 7825429

Can only attach 10 files . SO part 2 coming .

Click to expand...

Only this phrase is important:
"If you replicate the below you do so at your own risk. Any professionals reading please free to chime in. Any advice, comments and observations welcomed."

I am now mounting my compressor, slowly, with my "slightly different" own ideas ... thanks for your input, and others (@Barney and @Highwayman ... and perhaps i forget other people on the forum), I understand part of the electrical, pneumatic and mechanical stuff, but am not a specialist! Therefore, if something goes wrong: my fault!

And if somebody can help me: I am looking for a connector, let's say something like the Deutsch plugs to be able to connect and disconnect the 12V "live" wires of the car to the compressor. The Deutsch plugs are rated 25A max, and I want 40A minimum!