Piston Slap: to Mark VIII the Mark VII Air Suspension

Sajeev Mehta
by Sajeev Mehta

TTAC Commentator furiouschads writes:

A Mark VII is in my sights. I like the Mark VIII air suspension control that lowers the car when it hits 60 mph. Will a Mark VIII suspension control box work in a Mark VII?

Sajeev answers:

WOW: you mean someone actually can afford to spend the $300-2000 in new/used/aftermarket/OEM replacement parts to make a functional Lincoln air suspension system on a fully depreciated hooptie? You mean someone else out there doesn’t pigeonhole these systems with the nightmares made by manufacturers in a more European locale?

So sure, why not lower a Mark VII air suspension at speed? I poked around the wiring diagrams for a 1988 Mark VII and 1993 Mark VIII and wasn’t totally horrified at what I saw. Matter of fact, I’d be tempted to integrate the 1982-83 Fox Continental variable ratio steering system into it, as the Mark VIII’s air suspension “control box” also controls its speed sensitive power steering.

But being a complete Fox Body geek isn’t a great idea —welcome to my hell!– and adding the Mark VIII’s lowering capabilities is already challenging.

1988-1989 Mark VII LSC

It isn’t easy because the Mark VII air suspension is a different beast: boasting the same number of ride height sensors (two front, one back) but each sensor has an extra (4th) wire. The reason escapes me, as someone ran off with my Mark VII service manual. While it might be possible to convert to Mark VIII sensors, hopefully that isn’t necessary.

The “hard” part is actually the easiest: the lowering feature comes via communication to the VSS (vehicle speed sensor), readily available at the engine computer (in the kick panel, tough) or speedometer (easy).

If you get a Mark VII that isn’t hopelessly in need of attention, get a Mark VIII suspension computer and mock it up. After you get the shop manuals for both and do a good job with RTFM…son!

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

Sajeev Mehta
Sajeev Mehta

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  • Relton Relton on Sep 08, 2014

    As usual, there are lots of posters here who don't really know anything about air suspension. Most of the Ford horror stories are the result of people trying to fix a system they know nothing about. Often expensive parts are replaced when all that is needed is a retaining clip on the link from the axle to the sensor. A common problem on the rear axles of Town Cars and Continentals. Millions of Fords have air suspension that works so well the owners don't even know they have it. Every year, millions of perps ride to the slammer in Ford cop cars with rear air suspension. Millions of Ford SUVs are driving around with completely functional air suspensions. And, now, over half a million Ram trucks & Grand Cherokees have left the factory with air suspension. Really, if air suspensions are such a bad idea, why does every tractor trailer and transit bus have an air suspension? Busses since the 50s. Not to mention nearly every high end car, and lots of special off-road Jeeps. As far as grafting Mark VIII computer systems to a Mark VII, I suspect that it would be a major project. I think the VIII has a different set of protocols than a VII. I am sure that the later VIIIs are different than the first VIIIs. If you want to change the height manually, it is relatively easy, conceptually, t wire a resister either in series or in parallel with each sensor (here you have to read the manual. I can't remember whether the resistance increases or decreases with a height increase). Then wire a bypass switch around the resistors. When the resistors are bypassed, the system will maintain the standard ride height. Flip the switch and the ride height will change. If you just want to lower the car, you can simply adjust the length of the links to the sensors. Either way will retain the constant height and constant ride frequency of the air suspension. There used to be a company, All American Air, that made parts for Lincolns, and was run by a very competent guy. I haven't messed with Lincolns for a few years now, so my memories of specifics isn't what it used to be. I've said this before, but my experience with Fords is that their steel springs fail quite often, much more than their air suspensions fail. Google "Taurus front springs", for example. The MN-12 cars, in northern climates, also suffered broken springs. Parts places used to keep them in stock. Bottom line: keep the air.

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    • Sajeev Mehta Sajeev Mehta on Sep 09, 2014

      Brilliant, thanks again relton. Glad to hear from you again.

  • Redman Redman on Sep 19, 2014

    The Mark 7 was a fine effort - classic Lincoln styling cues coupled with boy-racer Mustang power. Factory BBS-type wheels also added a great touch. Now the Mark 8, that one hit a whole new high: world class 4-valve per cylinder DOHC V8; computer-driven four-corner air suspension (Caddies of the era were rear air only); and that look - that sharp, razor-edged front end and fighter-cockpit interior the likes of which we haven't seen since. Make mine triple black with a moonroof and chrome Octastar wheels.

  • JOHN One is for sale on an ebay car donation site.https://www.ebay.com/itm/305579991767?itmmeta=01HYHVJ49MCC6HEWQY5AX9MX85&hash=item4725fca2d7:g:k9cAAOSw5V5mThFw
  • Scott So they are losing hundreds of millions of dollars and they are promising us a “Cheaper EV”? I wonder how that will look and feel? They killed the Fiesta because they claimed that they couldn’t make a profit on them and when I bought the first one in late 2010 they couldn’t deliver the accessories I wanted for it! Then I bought a 2016 Fiesta ST and again couldn’t get the accessories for it I wanted. They claimed that the components were going to be available, eventually. So they lost on that one as well! I don’t care about what they say anymore. I’ve moved on to another brand.
  • Michael S6 CX 70 or 90 will not be on my buying list. Drove a rental base CX 90 and it was noisy and the engine noise was not pleasant. Ride was rough for a family SUV. Mazda has to understand that what is good for Miata isn't what we expect in semi luxury SUV. My wife's 2012 Buick Enclave has much better Ride and noise level albeit at worse gas millage. Had difficulty pairing my phone with Apple CarPlay
  • Michael S6 What is the metric conversion between one million barrels and the number of votes he expects to buy.
  • NJRide This could give Infiniti dealers an extra product maybe make it a sub brand