My wife drives a 1998 Ford Expedition. In general this has been a great viehicle, as Ford has known how to build great trucks for over 60 years. It has 180,000 miles on it and still runs great.
The biggest problem is that it is an upper end model, so it came stock with the 3rd row seat (+), 6 disc CD changer (+) and the air ride suspension from the Lincoln Navigator (big -)
When the air ride works, it's actually pretty cool. In theory it's great for towing, because you can load up a very heavy trailer, and the air bags will pump up until the rear is the right height. Thus you get all the advantages of a soft suspension for town driving and a hard suspension for towing.
The problem? You have pneumatic (air) components mounted to the bottom of an off-road viehicle. Let's face it, air lines and sharp rocks are never a good mix.
A couple weeks ago, the air suspension finally failed completely. I had resigned myself to replacing the rear air springs, but a quick perusal of the Ford forums convinced me to do something else: ditch the air ride and install a coil spring conversion.
The kit is basically 2 huge-ass coil springs, and a set of rubber seats for the springs. I opted to change out the rear shocks at the same time.
It took 4 hours start to finish.
1) Jack up the truck by the Frame as high as possible and put jack stands under it. It would have really helped if UI didn't have a full fuel tank (about 175 ls of fuel).
2) Jack up the rear axle, and remove the wheels.
3) Remove the nuts (18mm) attaching the sway bar, using 18mm socket wrench.
4) Remove air shocks. Pry off the bottom using a pry bar and pop off the valve at the top. Marvel at the amount of dirt and dust trap[ed by 180,000 miles.
5) Attempt to remove the bolt/nut attaching the bottom of the passenger side shock to the axle assembly.
6) Drive to Home Depot to get a 18mm box end wrench.
7) Drive to Lowe's where they actually HAVE an 18mm box end wrench.
8) Remove the bolt/nut attaching the bottom of the shock to the axle assembly.
9) Remove the screw and J-nut attaching the upper shock mount.
10) Repeat shock removal for the driver's side. Curse Ford repeatedly for placing the gas tank in the way.
11) Remove upper shock mount using a socket wrench, shallow socket, and piece of irrigation pipe on the wrench handle.
12) keep going, this is going to take a while.
13) Install the new shocks (top mount only). The J-nut is held in by the shock itselt. (this is the tricky part)
14) Drop the rear axle as far as it will go. Install new rear springs. Method: Mongo them into place.
15) Cut the shock retaining straps, and attach the bottom bolt/nut for the shocks.
16) Jack up the axle enough to attach the anit-sway bar.
17) drop the frame and put away your tools.
A) Do the passenger side first. Everything is easier to get to, so it's easier to figure out how the parts assemble/disassemble.
B) Home Depot's Tool selections sucks.
C) Coil springs can really increase your ride height.
D) The spring conversion kit is way better than replacing the air springs with more air springs.
Sorry that there are no pictures, but I did most of this after dark with a drop light.