Thread: Advice about solenoid valve block rear suspension.

Hi Joel, good description mate.

Just for a price reference on the Wabco (what Land Rover use in the D2) valve block. I paid $50 for my second one.

Yes I purchased 2 for $50 each also, it doesn't seen too bad if they work, WABCO is not cheap stuff, so I expect they are quite expensive to buy new.

Also factory standard under the D2 the "air in or up" is controlled by powering the compressor. I use that signal (power) to open the "air in or up" valve and my compressor is wired "ON" with my accessories/ignition then controlled with a pressure switch.

Yes my compressor works on a pressure switch as well, it cuts out at 120 psi, and has a 3 or 4 liter tank. I'll be copying your idea.

You need a second valve block as the Wabco valve block has 3 ports. The middle port gets connected to the left, right or both ports depending if the left, right or both valves are open.

So mine is set up that on the first valve block the centre port goes to the second valve block. The left port goes to my compressor and the right is my exhaust. So when the left valve is open air flows from the left port to the centre port and onto my second valve block. When the right valve is open the air flows into the centre port from the second valve block then vents/exhausts out the right port.

The second valve block has the centre port connected to the first valve block. The left and right ports are connected to the left and right air bags. Left, right or both valves are opened and closed depending on weather the left, right or both bags require filling/raising or emptying/lowering.

That's a clever idea thanks for the tip, just as well I bought 2, the good thing about your idea is you are using the same part twice, so one spare will cover both. ( Dam I need to buy another one But two of them in series and a spare is still less than half the cost of a specially designed sol v/v.
Another advantage is 2 valve isolation so the bags shouldn't go down easily.

I made your description into a crude drawing, ( air tank omitted), see attached.

I have bought a small control panel with a twin needle pressure gauge off ebay (Air ride), including two rocker switches. ($110 delivered).

I'll work out the wiring diagram when I get the switches. cheers simmo

In my experience only mate, the air tank is a waste of time. I had one and left it there for a while but had a leak once and I figured removing the "T" piece on the tip of the tank was 3 less places that could leak.

Air tanks don't actually hold much air. My initial idea was that when I was inflating tyres, I could fill one tyre and the compressor would continue to run while I put the cap back on and walk to the next tyre and it would save a little time because I would have this air being stored. Well you learn that even with the tank full at (140psi cutout) it will only provide a very few seconds of air before you are running solely on the air from the compressor. The other idea was I could drive around town and the air compressor wouldn't be running all the time because I'd have this storage of air. Yes the bags don't use much air when raising or lowering but when your tank is empty (90psi cut in) it takes a good 45 seconds or so to fill the tank because at 140psi, it's pumping more pressure than volume. So just for the bags, it's a 5 second burst here or there or 45 seconds occasionally.

The thing with the SLABS as well. It will let air out as you brake and stop at traffic lights and fill again when you take off. It wastes quite a bit of air actually. I have been meaning to fit a normally open valve on the exhaust line that will close with the brake lights so it doesn't waste air but I haven't got around to it. I tried fitting a normally closed relay to the exhaust valve and connecting it to the brake lights but the SLABS throws an error when it detects the exhaust valve is disconnected.

Happy Days

Hi Joel,
I'm tending to agree with you about the air tank, I had the same Ideas as you, but its been there for 10 years, and will hold air for a long time. I made it out of an old fire extinguisher. It does mean you can pump up one tyre quickly , then as you say your relying only on the compressor. The air tank is handy when I use my air gun for blowing things and cleaning them. (once a year )
I might retire my existing onboard compressor to suspension duties, I have a new one, a fairly big 2 cylinder unit for pumping up the tires.
By separating the two compressor duties I can use an air dryer for the suspension only.

Interesting about the SLABS airing up and down the suspension each time you stop etc. I won't have that problem because I'll only be adjusting the height using the rocker switches. I do have question about the tubes though. My existing system is all piped with black poly tube and the push in fittings the tube size is about 6 mm OD I think. The WABCO solenoid valves do they have push in fittings already? or are they threaded? did you have any problem buying compatible tubes and fittings? cheers simmo

I just modified my factory compressor body by threading the inlet to take a push-in fitting then you can use the existing valving including the exhaust,Then use the power feed to the aftermarket compressor.For the defender you will need something electronic to tell the compressor to turn on if you want auto levelling,Something like the d2 level sensors only with more adjustments.I will find some pics of the modified compressor tonight.

Hi Lewey,
I won't bother with the complication of auto leveling, I can adjust the rear suspension pressures in the cab using the rocker switches. cheers simmo.

Lewey & Joel, This is my proposed wiring diagram using the 2 D-2 solenoid blocks, and the two rocker switches supplied by Air ride. I haven't seen the switches yet, I'm fairly sure they have double contacts on them, if not I'll have to use some mini relays.

I've taken your idea to bypass the air tank for the suspension & save on the compressor run time. The compressor will start only on a suspension "UP" command. Because there is a twin needle gauge to monitor the suspension pressure I can keep an eye on the pressure in each air bag.

I expect they will not need much attention, I had air-ride shock absorbers on a station wagon years ago and the air bags only needed topping up every few weeks.

Its getting very close to Christmas so remote control might have to be in January. cheers simmo

pretty sure the D2 system levels from side to side as well,to cater for side slopes etc

Hi Lewy, yes D- 2 does level automatically side to side but mine wont, D-2 has its own brain, defender has to share mine, there's not much extra capacity there

Mine will be similar to a conventional suspension car, I can level it for' and aft & side to side in the driveway, but once its moving I'll just leave it alone. My current spring set up is a little down on the driver side, because of me and the 42 liter sill tank and my swing out wheel carrier is on that side as well.

I try to put heavy stuff on the passenger side to level it up. ( no need to share that thought with my wife . I expect I will have to put a few psi extra in the RHS to level up side to side. cheers simmo