By on November 1, 2019

2003 Mercury Grand Marquis, Photo: Ford Motor Co.

Loooongtime TTAC Commentator Nate writes:

My barber is another Yankee-to-West Coast transplant and he brought a low-mileage 2003 Mercury Grand Marquis. It’s very nice but every now and then the air suspension decides to get wonky and the car settles down as he’s driving along. As a barber he doesn’t have much $ to throw at it, and he asked me if I knew what to do.

I think this is a Panther chassis so any old cop car or taxi’s coil springs and shocks should be a fairly easy air suspension-to-coil springs retrofit but I’m physically not up to the job. How do I find one of the myriad hole-in-the-wall shops that fixes up old cop cars for the movies and TV?

I’m sure they’d have the parts and knowledge on hand and be affordable to boot. Once this is fixed he’ll consider replacing the weepy AC evaporator deep inside the dashboard (shudder).

Sajeev answers:

You think this is a Panther Chassis?

How poorly have I been educating everyone about Panther Love?

Of course it’s a Panther, hence why any shop can do the air-to-coil conversion with a donor (i.e. 1998-up, avoid cop car spring rates unless you do all four) with springs, rubber seats and this video. Or, if they don’t venture out to junkyards, the conversion kits are very cheap.  Even the kits that include new shocks are cheap, for most.

But the cheapest way is to recruit someone (i.e. free labor) to pull junkyard springs, rubber seats (hopefully still intact) and watch that same video for the install. Convincing someone to help might be tough if Mr. Yankee has no able-bodied family or friends in town.

Since it seems neither of you are in a position to get used parts, I’d recommend ordering springs and rubber pads online (WESTAR #CK7800 could work, I’ve had good luck with their air springs on my Mark VIII!) and call around for the best price on installation.  Someone’s gonna take the job, and then we can all love this Panther.

[Image: Ford]

Send your queries to [email protected] 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. 

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33 Comments on “Piston Slap: The Barber Shop Coil Spring Swap?...”


  • avatar
    Art Vandelay

    I thought the air suspensions on the Crown Vic/Grand Marquis were simple beasts compared to something like the Mk VIII. Might be cheaper to troubleshoot and repair it.

    • 0 avatar
      28-Cars-Later

      I encourage Sajeev to correct me but I was under the impression Mark VIII’s air ride was custom to the model. The Panther IIRC offered air ride on the rear only I believe as an option, but as far as the complexity goes between the two offerings I am unsure.

    • 0 avatar
      Scoutdude

      Define simple. The Panther has rear only while the VIII has 4 corner air. So yes fewer parts are present on the Panther and thus a complete replacement will be cheaper. However the VIII having air in the front uses air-over shocks and thus you can’t just replace a bag on the front corner you have to replace the unit. So yeah that is much more expensive than a bag.

      On the other hand they do share some parts, ie the compressor, dryer, and rear solenoids and the principles of operation and trouble shooting are the same but with twice as many wheel ends to deal with.

    • 0 avatar

      Odds are it is NOT cheaper to troubleshoot. At this age the odds are that the bags are cracked and will leak, if they aren’t already. If you are someone on a low budget, just give up and install coils. The parts are so cheap right now.

      I would never do this, but I am fortunate enough to have the cash flow for new/reman rubber bags. And if Westar does coil springs like they do air bladders, it’s likely a safe, cheap and easy swap.

      • 0 avatar
        Scoutdude

        See below, Nate certainly can help do the proper diagnosis, sitting in the driver’s seat with a $20 investment. A visual inspection of the bags only takes a couple of minutes.

        Checking the price of the kit you listed shows it at around $150 while a pair of bags with new o-rings will set you back $200. However the conversion will add time to the job as you’ve got to disconnect one end of the shocks to let the suspension drop far enough to wedge the springs in there.

        Of course most shops will tell you that you have to replace the shocks with ones designed for steel springs and the next thing you know you have a $500 bill.

  • avatar
    dividebytube

    I don’t remember my 2001 MGM having an air suspension. Was that an option only? It certainly did not ride as smoothly as my (ever leaking) air shocks in my 1994 Buick Roadmaster.

    • 0 avatar
      Mike Beranek

      I believe the “air shocks” on GMs like your Roadmaster are only for load-leveling. There should be coil springs back there.
      You can replace the load-leveling shocks with regular ones if the compressor goes bad.

  • avatar
    87 Morgan

    I would think a local Les Schwab tire center could handle a job like this we ease, and I have found their pricing to be fair and reasonable. I am sure others have horror stories, but for me where I live, the Les Schwab store has been a fantastic addition for quick affordable work on suspension bits and pieces and tires of course.

  • avatar
    Kyree S. Williams

    Funny you posted this. There’s some major suspension work in my immediate future. The 2004 Jaguar XJ Vanden Plas I bought as a cheap toy has three leaking air springs (I suspected this when I first test-drove it).

    There are coil-over kits, but they cost almost a grand, which is not much less than I found new replacement air springs for. Specifically, the coil-over kits have a module to trick the CATS system into thinking everything’s there, or it will trigger an Air Suspension Fault light.

    So I ordered all four replacements, which came in on Monday. This weekend, I’ll be doing the swap. It’s really rather easy, especially since there aren’t any dangerous tensioned coils with which to contend. Bonus: I can probably sell the old air spring cores for $50 apiece and recoup some of my outlay.

    I will also be replacing the front sway bar bushings, replacing the transmission mount, fixing the sunroof, and reupholstering the headliner. Spark plugs, a coolant flush, and brakes and rotors are also in this car’s future. I may do everything but the coolant flush.

    For a Panther, I would absolutely do the swap and not look back. Parts are cheap, and they’re easy cars. If you can’t do it yourself and you’re on Facebook, see about finding a local Panther group. I’m sure someone there would be willing to help. Heck, they might even do it for free (not that anyone should feel entitled to free labor), because people can be that nice. If you’re going to do OEM coils, my recommendation would be to find the P71 ones that were on police interceptors; the standard ones are too softly sprung for such a heavy car.

    • 0 avatar
      crtfour

      I enjoyed reading this because I used to have a 2004 XJ8 and replaced the air springs with coil assemblies in my garage. It was easier than I thought and I just unplugged some kind of module behind the rear seat and it got rid of the warning light. Other than that, it was a great car.

    • 0 avatar
      crtfour

      “The 2004 Jaguar XJ Vanden Plas I bought as a cheap toy”.

      I love the saying that there’s nothing more expensive than a cheap Jaguar (or insert other European brand).

      • 0 avatar
        Kyree S. Williams

        Indeed, there isn’t. But you can take a whole lot of the bite out by doing the work yourself. The local Jaguar indie shop wanted $6,500 to rectify all of the issues, which is more than twice what I paid for the car. I secured all the parts for under $1,500, and I reckon the work itself is worth a weekend or two.

        Some of what I’m doing is because I don’t know the history of this car too well, so I want to preserve it by doing preemptive maintenance.

        What’s nice about the X350/X358 XJ is that it’s not unreliable; it’s just finicky, in that classic British way. Whereas a contemporary S-Class, 7 Series, Phaeton or A8 is a ticking time bomb. Also, none of them looks as timeless as the Jag.

    • 0 avatar
      ToolGuy

      Kyree,

      My 2005 non-Jaguar recently made the unilateral decision to preemptively disable the sunroof in the fully closed and sealed position. So far I concur with her decision.

      (I recommend the 3M Headliner Adhesive, if you have need of such – it worked well for me. Ordered some Super 77 for an upholstery job on a different vehicle and was seeing mixed reviews from people attempting to use the 77 on headliners.)

      • 0 avatar
        Kyree S. Williams

        Yeah, something’s off with my sunroof, and it moves freely. I ordered a sunroof repair kit. Apparently, the XJ used the same sunroof assembly as the DEW98 sedans (Lincoln LS, Jaguar S-Type), which made a repair kit cheaper and easier to source than it otherwise would have been. Also, the sunroof seal is bad and has allowed water to damage the headliner, so that’s why that’s out…on top of the typical sagging issue.

        Good recommendation, on the adhesive! I bought some no-name stuff from JoAnn fabrics, but will probably return it.

        • 0 avatar
          ToolGuy

          You might see dramatic differences in initial tack/repositioning depending on how much you spray, how long you wait and whether you spray one surface or two. Test it some before doing any large areas [I got myself in trouble using the Headliner Adhesive on another project and spraying both surfaces.]

          Best of luck with your project!

        • 0 avatar
          krhodes1

          Sunroof seals really don’t keep water out, they prevent wind whistles. If you are getting water into the headliner, there is something wrong with your sunroof drains. Nobody ever cleans them out, and it should be a regular maintenance task. Compressed air will usually do it, but sometimes you need something like a length of bicycle brake cable to rod them out.

  • avatar
    Lorenzo

    What about the weepy AC evaporator? In most parts of the west, AC is a necessity. Is there a quick fix for that?

  • avatar
    Jagboi

    On a Panther, the heater core is in the dash, the AC evaporator is in a box in the engine bay. It’s much easier to change. That being said, they rarely leak. I’d be looking at a fill port schrader valve or a sensor O ring first before replacing an evaporator.

    Air suspension is rear only. Look at where the lines go into the air bag, failure can often be fixed by replacing the O rings that seal the supply line, the airbag itself is usually good.

  • avatar
    Scoutdude

    NOOOOOOOO! Don’t pay more to ruin the vehicle than it would to properly diagnose and repair the problem. The system is actually pretty simple and easy to diagnose and repair along with being pretty reliable.

    If the bags were bad it is highly unlikely that it would only drop while driving, it would also drop while parked. It also makes the solenoids and o-rings unlikely as they would tend to leak whether the vehicle is being driven or parked. So it is highly likely that the system is commanding it to vent and there are 3 solenoids that must be commanded open for that to occur, one on each bag and one integrated with the compressor/drier for both bags to deflate.

    It sounds like it does return to proper ride height on its own, so that means the compressor is still working.

    Does the air suspension light come on or flash when this occurs? When the computer doesn’t think it is maintaining trim it should turn on the light. When it turns on the light due to a leaking bag it will have run the compressor the maximum time limit and shut it down to prevent damaging it. Once enough time to cool has passed and you restart the car the compressor will run again.

    However if it drops but doesn’t detect a problem then it can be narrowed down to the one sensor and its wiring that the computer uses to determine ride height.

    So you want someone with a good scan tool that can actually read the VAPS/RAS module’s codes and data.

    Or you can spend $15 or $20 and obtain your own. You just need a ~$15 elm dongle, available from Amazon or E-bay and the ForScan app for your phone, a free program for your Windows laptop or tablet. There are blue tooth, wifi, and USB elms so you need the right one for the device you’ll be connecting to.

    Now you can look at the inputs; height sensor, VSS, door/trunk ajar and the outputs, L & R solenoids, vent solenoid and compressor relay in real time with a recording that you can play back after the suspension acts up. With the app you can actually set it so it connects and opens the dashboard to the last module you have looked at and starts playing/recording. So it is as easy as turning the car on and clicking on the icon to start reading and recording data, you can leave it running in the back ground and then look at it later after a trip where it acted up.

    Much better to replace a ride height sensor for $40 and 15 min that spending much more on springs and at least an hour of labor, or better yet spending 30 min finding the shorted wire.

    • 0 avatar
      Kyree S. Williams

      Good advice, as always! You know these cars well.

    • 0 avatar
      golden2husky

      Scoutdude. Unrelated except for being a FoMoCo product but is there a way to read ABS data on my 92 Sable with the purchase of available apps or cables? I have intermittent ABS engagement when coming to a stop. This was a Piston Slap question once. I replaced all four wheel sensors with no improvement. I suspect one of the tone rings is rusted to the point of not allowing a proper signal but I have no way of knowing which one… My apology for the hijack

      • 0 avatar
        Scoutdude

        Unfortunately being older than 1996 there is no cheap aftermarket solution to read data or codes. Lots of professional grade aftermarket tools would do that back in the day, but they are very expensive.

        • 0 avatar
          golden2husky

          Thank you for your reply. And I agree with you 100% – there is far too often an urge to rip stuff out and compromise the vehicle by not doing proper diagnosis in the first place. If I still had my MK VII LSC I’d never rip out the bags and put in springs. A repair shop much rather make a quick buck than investing time in diagnosis.

  • avatar
    -Nate

    THANK YOU ALL ! .

    I knew I’d get the straight skinny here .

    #1 : I maybe should have said “I know it’s a Panther Chassis” but someone would have picked that to death so I was trying to be polite .

    Scout Dude really nailed it except as soon as he said ‘computer & app.’ it was out of my league / interest .

    He’d $pent some $ having the air bags checked for leaks, they said they were fine and that’s where he stopped as no one would even look further for less than $800 ~ $1,00 plus parts .

    In the end the very first place I’d suggested, Tyermans Frame & Alignment on Magnolia in Burbank, Ca. fixed him up with coil springs and shocks for $200 and he’s loving it .

    I’ve been using Tyerman’s for decades, they’ve fixed several vehicles for me that had steering idlers and worse simply rip out of the frame .

    Now to see if he’ll fix that weepy AC Evaporator .

    I never did find any of the many old cop car / movie prop shops .

    -Nate

    • 0 avatar
      Scoutdude

      Bummer, it is very disgusting to hear that they just didn’t want to deal with it so they quoted a price designed to drive the customer to do they work they wanted to do, instead of fix the car. Of course in the process turning what would have been an under $100 repair into a $200 bill.

      • 0 avatar
        -Nate

        Typical, sad and frustrating but not disgusting to me, I’ve seen it many times over .

        -Nate

        • 0 avatar
          Scoutdude

          I’d love to know just how many transmissions have been sold over the years that just needed a new solenoid or some other $2-300 repair but the shop didn’t want to take the time to figure out the problem, or just saw the $$$ of selling a rebuilt transmission.

  • avatar
    incautious

    there are companies that make kits for replacing the air suspension. Cheap and takes about an hour or so. Had a 1990 TC used it to hot shot deliveries to customers(big trunk) did the spring swap and WHAT A DIFFERENCE!


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