Arnott Coil Spring conversion

Town

Senior Member
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Ottawa Ontario Canada
But, the compressor switch is to be turned on, correct? To complete the circuit. Right?
No I don’t think so. There is no switch so the connection can be removed and insulated against a short to ground. When you order the conversion kit there will be instructions. Earlier models will allow a wire to be cut to prevent the instrument cluster showing the air suspension light and the message. Later models will not allow that and keep the light on. Black insulation tape circle over light makes it less anoying. The instructions with the kit explain what you have to do.
 

dave42

Senior Member
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Leander, TX C.K.U.
Another stupid question. After converting to coil springs how do you keep the dashboard warning light off?
As Town mentioned, you don't, at least not on the latest generation of TCs. That's why he mentioned the black tape over the error message (I just ignore it on mine). Now, there are some folks who have done some workarounds if you are good with searches. One involves leaving the solenoids in the car (wrap them in plastic bag, zip tie out of the way) with wiring plugged into them, and then taking apart the height sensor components and manually adjust to the proper voltage reading for the correct height (2.8V maybe?) and secure the parts in that position with duct tape or whatever. Then turn on the switch in the trunk and the car thinks there are air springs at the correct height. Someone else was trying to find out what the resistance would be of the height sensor when set for the right height and replace it with a resistor. Another guy somewhere mentioned (I think this may have been a Grand Marquis) he left his height sensor in place and since the car on coils was the correct height, it worked out the same way. And yet another guy I seem to recall mentioned being able to disable the message with Forscan.

Normally with the swap to coils, you just turn off the switch in the trunk and live with the error message. Mine could be easily converted back to Air. If one had no plans to do so, one could make some money selling the compressor and height sensor.
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Brian J. Patterson

Well-known member
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Northern Illinois
Hi, Babyburr.

Is there anything wrong with your air suspension right now? If not, I'd suggest not changing it out right away.

IIRC, you tend to have most of your maintenance and repair done at a shop instead of doing it yourself. This means that you will pay more, since most shops sell their parts at "suggested retail" (and keep the difference) as well as charging you for installation. This is actually more than fair enough as far as it goes.

The "retail" price your shop would charge for the Arnott kit, as far as I can tell doing a quick internet search, is around $300 or so. The shop themselves would give you the "actual" number since it's their business. Figure two shop hours or so, and you're looking at $500-$600 for the job. Since the kit includes new fresh shock absorbers, there will be some time charged for replacing them, too.

Your shop might also have a "favorite" brand that they prefer over Arnott, and price it lower accordingly. I have no personal experience on how good or bad the other brands are. Your shop will probably do a better job with a parts line they routinely install instead of a brand they buy one time for one customer, and that's if they're "able" to get the Arnotts at all.

"Most" (but not all) people who go for the coil spring conversion do so because it's noticably less expensive than replacing the defective parts on their air suspension with new air suspension parts. You can typically buy the Arnott coil spring kit for about the same price as one Motorcraft air spring.

Others make the switch because the garage they took their car to are clueless on correctly fixing air suspension systems, and push the springs rather than learning the craft. If they charge you sixteen hours of shop labor, it's still a financial bloodbath even if they give you the parts for free.

The rest, FWIW, convert to coils as part of major suspension modifications to make their Town Cars ride and drive like Crown Vic Police Cars or Mercury Marauders, and don't want to bother with finding air springs that would have the spring rates they want.
Back to most people buying the conversion kits, $600 is cheaper than $900 or more to replace both air springs, both solenoids, and both shocks with new ones. And if you're trying to make chicken salad on a chicken s??t budget, saving $300 or more to repair your car is something you can't easily ignore.

But the coil springs don't ride as smoothly as the air suspension does when the air suspension is in good repair. They also don't level the car for both heavy loads and light ones. This won't matter so much if the system is completely shot.

But if it's working okay, or only starting to go, you don't need to be in any hurry replacing the air suspension. This will also give you more time to figure out and decide if the smoother ride is worth the extra $300 to fix the system, if the system actually needs fixing. If you can tell the ride difference between the air suspension and the coils, buy yourself some happiness later by spending the money now. If not, than save the $300 for something you will get $300 worth of enjoyment out of.

I would suggest talking to the shop you go to for your repair needs and getting a quote from them for the conversion, as well as finding out what brand(s) they recommend. Just for comparison, if your air suspension is starting to go bad, I would also try to get a similar estimate to return the air suspension to a good state of repair. This will tell you what you'll actually pay instead of getting a guess from "some guy on the Internet." Unless your air suspension is failing badly or if you plan on driving on a long-distance trip any time soon, there's no hurry either way.

As for "turning off" the air suspension warning on your dash after the conversion, @dave42's post has most of the ideas. You will likely not be able to turn off the light in the PCM, and if you can you'll probably need Forscan instead of the Snap-On computer most independent shops tend to use. In 2005, air suspension was standard equipment with no other options. Turning the light off in the PCM from what I've seen only works for the '10s and '11s where the air suspension was an option and the coil springs were standard. You might have better results. "Fooling" the system as dave42 described will likely be much easier, so long as the solenoids, ride height sensor, etc are still in good repair.

Good luck with whatever you decide to do. Please let us know what you decide on, and how well it turns out.

Thanks.
 

dave42

Senior Member
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166
43
Leander, TX C.K.U.
Babyburr, since your car is new to you, just turn off the switch in the trunk and drive it for a week. If the rear starts dropping then there is a leak and you are on borrowed time. If the rear stays up, then turn the switch back on and have confidence that you won't need to do anything to your air ride for some time.
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Brian J. Patterson

Well-known member
386
250
63
Northern Illinois
Babyburr, since your car is new to you, just turn off the switch in the trunk and drive it for a week. If the rear starts dropping then there is a leak and you are on borrowed time. If the rear stays up, then turn the switch back on and have confidence that you won't need to do anything to your air ride for some time.

Hi, dave42.

Sitting for a week or more with the system turned off without any dropping would be expected. Driving for a week with the system turned off would be the "ultimate proof" that the system is fully up to snuff, though it does seem counter-intuitive at first.

When the switch is turned off, the compressor is turned off, so no air is added. The solenoids are also turned off so no air is supposed to leave.

If @Babyburr had a major leak, he would have noticed by now. If he gets through all, or even a major part of a week of regular driving with the trunk switch off without noticeable dropping, that would be proof that the system is still good, if not "as good as new."

Depending on how much the suspension has to "work" during that time, there might not even be a "leak" per se even with some dropping. When the springs are compressed, the air pressure presses against everything inside the spring, including the solenoid valve. These pressure surges could force their way past an otherwise trouble-free pair of solenoids, or out of used but otherwise problem-free springs. This "forced leakage" would not be obvious with the first bump, or the second, or the third, but would eventually and gradually show up. You would also play hell at finding such a slow, driving-only leak if one were there to be found.

When the air suspension system is working, it's adding and removing air more often than you think. Any change in weight at the rear of the car that causes a change in ride height will cause the adding or removing of air from the system. This adding and removing would effectively hide any actual small leakage in the system.

Thanks.
 
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If going to coils I wouldn't waste my time or $ on the Arnott conversion coils. I'd just get Crown Victoria/Grand Marquis coil springs for far less $ and stuff those in.

Just took Arnott coils off my car, they ride way too harsh. Swapped in some no name coils I had lying around and the car rides way better.
 
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