Since there is not a lot of information on these kinds of installs I thought I would give the air ride system it’s own page, part of this was covered in the suspension section so this is a more in-depth look at the air supply system and the controls.
As I have stated in other places the goal was for an adjustable ride where I could maintain the same ride level with the car loaded or empty and I could have customized set-ups with driver only or driver and passenger etc. Also carrying the theme forward of having little modern technology I chose to do a manual system with paddle valves.
The control center of the system is a paddle valve box located between the seats, I welded up a little box, cut the rectangular holes in the front mainly with a Dremel tool (that ate up a lot of tiny little cutoff wheels), two switches were added as well, one to turn off power to the compressor if needed and the other, a touch switch, to activate my “lazy man tank drain”
I will try and explain what is going on in the above picture, this was taken during the initial mock-up that is why there is a quick connect air hose attached in the back, this is where a PTC (push to connect) fitting & air line comes from the onboard air supply. Starting from the incoming air supply in the back, it goes into a 1 in 6 out manifold, it is just an aluminum bar for things like shop air rated at over 200# pressure, it is not a special part like the air ride companies sell for $100+, I think I paid around $10 for it. There are two ports on each end that are plugged and four ports going out in front each have a check valve screwed into them, these are just compressor check valve with 1/4″ NPT male threads on the supply side (incoming) that screw directly into the manifold, the female threads on the outgoing side have 1/4″ NPT to 1/4″ PTC fittings installed, a short piece of 1/4″ air line goes to the supply inputs on the manual paddle valves (the paddle valves have barbed fittings, you just push the line fully on to them, if you want to remove the lines for any reason you have to cut the air lines off), the output side of the valves go to 1/4″ air lines and then to each individual bag.
The reason you want 4 valves and not just two, one for front and one for rear has to do with bag loading and the ability to adjust each corner individually, the valves and lines are relatively cheap as well. What bag loading is involves when the car goes into a lean like on a curve, if the two bags are tied together by a single line the outside bag will compress more than inside bag on the curve and force air from the outside to the inside making the lean worse and not keeping the road pressure where it needs to be.
The way I configured the valves was the left two are the left side of the car and, of course, right is the right side, mine are, from left to right, front left, rear left, right front, right rear. You pull the valve paddles up to add air and push them down to exhaust air lowering the car.
With a manual system like this you need to be able to tell how much air is in each bag. PTC tees were added to each air line as it exits the rear of the control box that is 1/4″x1/4″x1/8″ the small 1/8″ line runs up to the dash and connects to two multi gauges, one for the left and one for the right.
On the multi gauges the yellow pointer is the front bags and the white is the rears, the center gauge is tank pressure. Each line has a tee including the 3/8″ supply line that shows tank pressure. I mounted the gauges in a custom center console I am constructing in the Comet. I will write down what pressure is needed in each bag for ride height under different circumstances. BTW if anyone is wondering, the air bags are super responsive with the 1/4″ air lines.
A clean dry source of air is needed, I added an automatically draining water trap in the trunk, output runs to the control box manifold and input connect to the air storage tank.
The water trap (above left) contains a float that when the trap gets full it opens a valve to allow the water to drain out the bottom, I will be hooking a line up to the lower drain outlet so the water drains under the car and not in the trunk, the bottom of the trap is also removable so it can be manually emptied. The valves on the right side in the picture is a manual fill valve connected directly to the tank, it has a Schrader valve so a regular tire fill chuck can connect to it and a regular air quick connect that I have made a double-ended adapter to connect a shop air line to, the red shutoff valve is just added so air can be turned off while using the adapter and disconnecting the air does not allow air to escape if you don’t remove the adapter first. The quick-connect has a dual purpose because you can also connect an air hose to use the air from the system to air up tires, etc. it might even be able to run some air tools with a regulator added.
The air storage tank is 5-gallon aluminum rated at 200# with 5 ports and a drain port on the bottom, it is mounted hanging from and below the rear package tray.
On the input end of the tank, one port has a brass tee with a 175# pressure relief valve and a 110# on – 145# off pressure switch, the other port has a leader line with a check valve that runs to the compressor. The two ports on the output end of the tank, one is the main feed and runs to the water trap the other one runs to the manual fill/accessory valve. The 5th port on the side of the tank has a gauge in it so you can see the tank pressure from the trunk side in case you are manually filling the tank.
The compressor is a heavy-duty WoLo 860-C Air Rage rated at 200# 3.5 CFM continuous duty. I have not hooked it up yet so I can’t comment on how well it fills the 5-gallon tank. Even though it is rated at 200# the compressor shuts off when 145# is reached and in case of pressure switch failure the relief valve will activate at 175# before the tank reaches its specified limits.
The compressor will be hooked up with a manual switch in the car to shut it off in emergencies or maintenance but will run automatically through the pressure switch and a relay supplying a full 12 volts to it.
I keep talking about my drain valve that I have coined the name the “Lazy Man Tank Drain” basically the philosophy behind it is; “If it is easy to drain the water out of the air tank I am more likely to do it more often” and the tank is in a really inconvenient location to reach.
L.M.T.D. is basically a regular electric air system valve that most people use to control their air bags (one per bag to fill and one per bag to exhaust air, or 8 valves) they are not terribly expensive especially if you just need one (I am thinking around $10-$20 each) I removed the installed tank drain replaced it with a brass tee re-installed the manual tank drain back into the bottom of the tee and a 1/4″ PTC fitting in the side, added a short piece of tubing to the electric air valve with a few fittings and mounted the valve on a 1/2″ cast iron plumbing floor pipe flange that was screwed to the trunk floor (would have liked aluminum better than cast iron but couldn’t find one) with a hole going out under the car, that I had put a washing machine stainless screen over to keep out hole plugging wasps.
The wiring will go up the momentary switch below the paddle valves so pushing and holding the switch will activate the valve, purging water from the tank, releasing the switch will close the valve again. I hope to make it routine that every time I start the car for the first time each day I drive it to purge the tank. Since I left the manual valve on there it can be operated to purge the tank, in case the electric valve fails, the only problem would be crawling in the trunk to reach it.
One thing that I installed that more than likely will prove useless is a large bubble level in the console, it is quite sensitive and I may be surprised at its usefulness, but the thought was to get the car totally set at ride height and rake, adjust the level (it has three adjusting screws) and then you could adjust the level of the car from the driver’s seat allowing for different balanced loads.
The downfall to my plan (at least one) though you can get the car back to the same relative ride level as far as side to side and rake, you have no way to know how high the car is off the ground. If I could make a sensor that could tell if the lower front control arms are level (the lower control arms determine proper ride height they are designed to be level) some could be determined by the base air pressure but that would change according to load balance. You have to take this hypothetical because I have no real-world knowledge.
A Few Observations to Consider
These are the things I considered when designing my air ride system as a noob and on a budget.
Use as few fittings as possible, for two reasons, they are expensive for DOT fittings and every fitting is a potential leak, so far my system leaks are extremely small to non-existent, I am not sure I could even find them with soapy water but may try sometime.
Use a tubing cutter designed for air lines when making cuts that go into PTC fittings, a crooked cut will cause leaks, tubing cutters can be bought cheap.
Maybe not as important or possible for you but I ran all my lines inside the car except the two going to the front bags, I used stainless braided compressor leader lines for those and brought the lines through the firewall using bulkhead connectors that also connected the leader lines on the outside to the regular lines inside
Try to find DOT approved fittings and air lines, most of these are approved for big truck air brakes so they should be made to a higher standard, even though I am cheap and on a budget, I bought the better connectors and line mostly because I did not want to have to run down leaks or worry about lines blowing out of fittings. Even buying DOT fittings I still had one bad one I had to replace, it kept blowing the line out of the fitting.
I like to make sure there is a little extra air line when I run it in case I have to re-trim one at a fitting if you have few inches extra you can make a lot of trims before it is too short and you have to run a new line.
You can use brass plumbing fittings in some places but they may not be rated for high enough pressure and usually they are really rough and ugly.
As with all the pages on this site I will keep adding and editing this as I go.