PDA

View Full Version : rear air spring to coil conversion



ts-pa
07-25-2014, 10:26 PM
It all began with the ride height sensor. Swapped it out. Then the compressor replaced, twice. Not surprising since the replacements were pick & pull parts. Finally I had enough with the air springs now leaking.

Previously I had bought the Eaton rear springs (MC3895-1) with a one inch drop for my 2000 LS, but never got to put them in. So I put them into the Marauder instead. The Marauder has the Eibach lowered front springs already, so now the car has an interesting rake. All I need next is a mullet to really fit the stereotype, LOL! The free height of the springs measured about 14-3/8”.

I had previously purchased Energy Suspension #9.6101 spring isolators. I was doing the same mod that a crownvic.net member had done with cutting an opening in the thin lip area for the pigtail. When I placed them on the coil spring, I thought that the fit was good, but the pigtail could still rub the perch once installed. So I also purchased a set of Moog K6203-2 spring isolators. The two fit together very well. Over kill perhaps, but I didn’t want any spring creaking noises. I taped the isolators onto the upper end of the spring, the end with tighter wound coils, to hold them in place during installation.

I tried to do one side at a time, but the axle doesn’t drop low enough. With two jack stands on the frame just in front of the rear wheels, I removed the wheels and lower shock bolts to let the axle hang lower.

Removed the upper wire clip from the air spring. I found that a hex key hooked through the wire and pulled with a channel lock worked really well. Then popped off the air spring from the lower perch,, removing the clip from the lower perch on the axle. I disconnected the solenoid and zip tied it up in case I decide to return to using the air springs again. Be careful of your eyes when removing the old air spring as they collect a lot of debris at the top.

The springs are a little harder to install that what the youtube videos show for a similar rear coil spring kit. These Eaton springs are a cargo coil type, with the progressive coil pitch to handle loads with less sagging. Essentially ended up “bench pressing” the spring into place. Once on the axle perch, rotate the spring to keep the pigtails of both to be the same orientation. After rotating, shifting the upper spring end may be needed to have it centered onto the upper perch.

The ride is nice and firm. Kind of reminds me of a CVPI. Not too harsh, but more to my liking as I always thought that the air springs were too soft when unloaded. The easiest way I can describe the ride differences is when the rear tires roll over a crack in the road, such as a gap of two concrete sections. With the air springs, you barely notice the crack. With the coil springs, you can definitely notice the same crack. Not objectionable to me, but to each their own as to preference.

I didn’t do the wire disconnect yet, but now notice that my steering feel is a bit hard. As in feeling like it has very low power assist. Kind of like a truck without power steering. Is it correct that the RAS module controls power steering? Do I need to replace this module?

ts-pa
07-26-2014, 08:46 AM
http://www.mercurymarauder.net/gallery/showgallery.php/cat/719

ts-pa
07-26-2014, 01:48 PM
OK, took the MM out for a country drive. It is definitely more firm and more noticeable at higher speeds. I'd have to guess as my speedometer recently stopped working, but below about 45 MPH, I definitely like the firmer ride of these rear coils. Over 45 and you hit a bump, it is more noticeable. I wouldn't say it is too harsh, but more firm than the air springs. I can see where someone might like the air springs better in this example. As passengers, my family actually likes the ride better now than before.

jsignorelli
07-26-2014, 07:47 PM
I just had my air pump fail. The replacement is $ 229 or I can replace the entire air system for $ 339 and have new air bags as well. I think an entire replacement makes more sense as I'll have all new parts.
It is only money...easy come..easy go! Now all I have to do is get is in before Friday when I leave for the New Hampshire MM weekend.

ts-pa
07-27-2014, 04:42 AM
It would appear that keeping the air system is possibly cheap enough with aftermarket parts to be about equal with the cost of the coil conversion. I probably should have done a complete replacement, instead of by pieces. As you say though "It is only money...easy come..easy go!" is a falllacy as the "easy come" has been quite hard over the past few years.

Of all of the cars I've owned over the years, I never had to change a coil spring unless I wanted to do so. With the air ride, you have to consider it a wear item and maintain it.

So now I'm once and done. I kept the hoses intact in case I or the next owner wants to go back to original.

The rear suspension is so easy, that either replacement or conversion can be quickly done. Best of luck and stay safe!

71cyclone
07-27-2014, 08:01 AM
I just had my air pump fail. The replacement is $ 229 or I can replace the entire air system for $ 339 and have new air bags as well. I think an entire replacement makes more sense as I'll have all new parts.
It is only money...easy come..easy go! Now all I have to do is get is in before Friday when I leave for the New Hampshire MM weekend.

With the Marauders ,we have minimal problems compared with other makes. My neighbors 05 -500sl Mercdz. needed a left front shock and air compressor ,to the tune of 5,000 dollars with reprogram included. [ I know its apples and oranges ] but our cars are easy to repair and locate parts. 'Happy Maraudering ":burnout:

lifespeed
07-27-2014, 04:44 PM
With the Marauders ,we have minimal problems compared with other makes. My neighbors 05 -500sl Mercdz. needed a left front shock and air compressor ,to the tune of 5,000 dollars with reprogram included. [ I know its apples and oranges ] but are cars are easy to repair and locate parts. 'Happy Maraudering ":burnout:
Well said! While a few hundred bucks may be a lot to many of us, it is good to keep in perspective how affordable these cars are to own and maintain. And what you get is a real hot rod with solid performance, or better if you upgrade.


I just had my air pump fail. The replacement is $ 229 or I can replace the entire air system for $ 339 and have new air bags as well. I think an entire replacement makes more sense as I'll have all new parts. It is only money...easy come..easy go! Now all I have to do is get is in before Friday when I leave for the New Hampshire MM weekend.
To the OP, I highly recommend you only use Ford air springs. The aftermarket air springs, at least Arnott I know for sure, are not the same rate as OEM. These cars are highly sensitive to rear spring rate and shock valving. Get this wrong and your car won't ride or handle well!

I have a set of one-year-old OEM Marauder air springs for sale (http://www.mercurymarauder.net/forums/showthread.php?p=1402415#post1 402415)if you're interested. Sounds like you need a compressor too. Good luck.

ts-pa
07-28-2014, 02:56 PM
...Now all I have to do is get is in before Friday when I leave for the New Hampshire MM weekend.

There was a video on youtube where a man struggled to get the upper air spring clip off. I think he was using a screwdriver and pliers. I couldn't find my needle nose pliers, so I decided to try these tools. Worked very well; just hook, yank, and done! It doesn't matter which direction the clip is pointing, it will rotate towards you as you're pulling and then disengage with very little effort. I'd wouldn't be surprised if a simple hook made from a wire coat hanger would work just was well.

http://www.mercurymarauder.net/gallery/showphoto.php/photo/23998/title/long-reach-tools-2c-lol/cat/719

Don't forget to remove the lower air spring clip from the axle perch! It pops right out with an old screwdriver.

http://www.mercurymarauder.net/gallery/showphoto.php/photo/23997/title/lower-air-spring-clip-removed-from-axle-perch/cat/719