When I saw the title of the thread I thought "Oh dear, someone else asking for the impossible?"

And then I read it!

Bloody hell, if this all works in practice without impacting upon the drivability of the car when it's not towing then it's mightily impressive!!

Any idea of likely cost and time to install?

 

I'd estimate 8 hours to install assuming brackets and harnesses were prefabricated.
2 hours to remove coil springs and install air springs
1 hour to install level sensors onto subframe.
2 hours to install compressor & wire up power
2 hours to route wiring & hoses
1 hour calibration / debug

I think the whole install can be done without removing any interior panels, and without drilling or cutting any part of the car.

My parts total so far is ~$1600. Big ticket items were:
(2) used rear air springs & pigtails $550
Compressor with bracket & pigtails $255
Solenoid bank & pigtail $120
PLC $140

If I sell a kit, it would probably just be the height sensors & brackets, cable harness, power supplies, fusing and PLC. Or maybe just the pre-programmed PLC, BOM, drawings and schematics.

Most people say the air suspension rides nicer than coils. The rear shock dampening will be fully adjustable too, Im planning on going full firm when towing!

 

I will be following this closely as I'm very interested in what the results will be.
Personally, I wanted to go down this path, but after closer consideration, I've decided not to do so.....
I look forward to seeing your system completed and operational.

 

Seems way overkill for what youre doing but FRICKEN AWESOME none the less. If all youre doing is controlling air flow through a flow control i would think it could be controlled via something less complicated than a PLC.

 

I wasn't knocking your project friend.... you're still doing a lot more than what I'm doing.... so far, I'm only "talking" about doing anything at all.

 

Interesting project. Can your PLC control all 4 corners (I assume you are programming it yourself)?


Also why is WD hitch a no go for you?

 

The PLC I'm using could control all 4 corners, but I would need to buy additional IO cards (2 analog inputs, 2 digital outputs). I would probably just buy a second PLC ($130) and connect them with ethernet. The networking seems pretty seamless:

Yep, I'm programming it myself, it's the fun part for me. Nice thing is the programming software is available for Mac if you're a Mac user. Demo version of the software is free, I had my program written and simulated before I bought the PLC. Full version of the software is $69.

The Touareg manual states a WD hitch must not be used. There have been several threads on the topic, from my research the only way I see this done safely is to weld an additional support to resist the bending moment acting on the hitch.
https://www.clubtouareg.com/forums/f66/hitch-weight-and-warranty-287509-4.html

We also have a steep driveway leading to our side yard where we park our trailer. The standard ball hitch gives us less than an inch of clearance, a WD hitch would hang about 3 inches lower, so we would have to layout a path of wood blocks or something. I also just don't want to deal with a WD setup. My previous SUV had air suspension and it towed beautifully. It's nice to be able to raise and lower the hitch to tilt the trailer over obstacles, or level the trailer out when camping. I'll have full manual control over height, not just limited presets.

 

The Siemens Logo PLC uses Ladder or Function Block Diagram (FBD).

Yep, you change the ride height setpoint (all constants) in the PLC using the built in LCD screen and keypad, or you could program analog / digital inputs to select different presets.

With 500 lbs on the ball, my rear sags 1.25" and the front raises 0.5". I'm using the shortest after market ball mount I could find.

 

Here's a schematic of my air suspension if any one is interested.
http://etischer.com/touareg/airsuspension/TAS.pdf

Got my constant current power supply installed today.

Still waiting to install the compressor, but so far it's working well running off an air tank. Nice to finally have control over the shock dampening.

 

Here's a schematic of my air suspension if any one is interested.
http://etischer.com/touareg/airsuspension/TAS.pdf

Got my constant current power supply installed today.

Still waiting to install the compressor, but so far it's working well running off an air tank. Nice to finally have control over the shock dampening.

Bringing this back up.

You did a phenomenal job on this project sir.

Two quick questions:
1)It looks like you used the PLC's 5v for the level sensors. Were you able to piggyback the factory signal for the headlights?
2) On your adjustable power supply for the air shock ride quality, why the 8.55V? Great idea on the adjustability with a constant current PS

 

This is pretty bad ass and kudos to you sir. I was looking for an AirRide set up for my particular set up and might start reading up on your thread more often. My buddy specializes in bagging vehicles but I'd like the OEM type lift rather than the chassis dragging on the floor, my car is currently lowered but it does go off road once in a blue moon.

 

Also... why do they have a do not weld sticker on them? Are they actually hear treating the hitch.... or is it that their design is so perfect it must be left exactly auch to do it’s job (all rhetorical)....

It seems obvious they over designed and are a little full of themselves.

 

I understand. I’d love to put air suspension on all 4 corners. The controls were my worry especially towing with WD hitch (auto level and such).

As to the hitch moment. The WD reduces the moment under normal conditions compared to non WD hitch. I think VW was remis allowing a 600 lb tongue weight on non airbag equipped vehicles (with non WD hitch). I suppose some sag is normal.

On a different note. Where did you buy the air shocks and how much were they?

Does your system work with the stock ride height valve?

 

I imagine I could control 4 corners without much extra effort or cost, the program would be the same front/rear; just a copy/paste.

I bought my rear air springs on eBay, one was $280 with 63k miles, the other was $236 with 45k miles. I got them for ~ $100 cheaper than the auction listing by making an offer. There were cheaper ones out there, but I wanted ones with low miles. Everything else I bought new (lines, fittings, compressor, valve bank, PLC, power supplies...) I'm using the stock VW valve bank.

My rough calculations:
Assuming ball to chassis = 1 foot, the moment from 500lbs on the ball = -500 ft*lbs.
Now with a WD hitch w. 3 foot long spring bars, the moment is (390lbs * 4') = +1500 ft*lbs
Net moment is 1000 ft*lbs vs. 500 ft*lbs.

Again, real rough calcs but to me even under the most optimistic circumstance (just looking at static loading on a level road) the moment using a WD hitch is 2x. Once you factor in dynamic loading like going across a dip in the road or up a steep driveway (where trailer and vehicle make a V), the WD moment is probably much higher.

 

I tow with mine and use a WD hitch, but I admit airbags in the back would be nice...probably $400-500 nice. But awesome work, very impressed.

 

Here's a break down of cost, and list of parts now that the project is fairly complete and functional.
$1400 in parts + $70 programming license.

http://etischer.com/touareg/airsuspension/TAS%20BOM.pdf

 

Here's a break down of cost, and list of parts now that the project is fairly complete and functional.
$1400 in parts + $70 programming license.

http://etischer.com/touareg/airsuspension/TAS%20BOM.pdf

I may have missed it but does the Siemens unit raise and lower the vehicle as well?

 

I finally got the bracket for my compressor, PN 95835821000

The bracket bolts onto the chassis using 3 Rivnuts, but models without air suspension have only 1 Rivnut installed. Rather than trying to compress Rivnuts in such a tight space, I tapped two holes in an aluminum backing plate.

I wasn't sure what filter if any is used on the compressor inlet. For now I just stuck a Dyson sock filter over the end, seemed to be a good fit. When I lower the suspension, exhaust air blows though cleaning the filter.

 

Towed for the first time this weekend with air suspension. The air suspension worked perfectly, keeping things level. The biggest improvement in handling was the ability to stiffen the rear shocks, we ran with 600mA on the shock valves. Super happy with how it tows now, especially on bumpy uneven roads; we get a nice solid thud rather than the constant ocean waves we used to feel.

 

Bravo, Sir. Bravo.

 

good work, glad to see I've inspired people.

Might I suggest for a cleaner OEM look, use the OEM load sill lowering buttons for height adjustment.



Simple 3-wire connection. Common, up, down.

 

Yep, you're thread on air suspension convinced me go forward with my swap, thanks for that!

I'll shop around for the rear leveling switches, do you need to replace the whole panel or do the switches snap in?

I'll probably get the shock adjustment dial too, seems like something I'd like to tweak while driving.