Installation of Rear Coil-overs and Struts

This is the layout of the rear suspension, using coil-overs. I took this picture when I first got the spring and struts, before I looked at my stock setup. As I noted, the upper spring pad that comes with the coil-overs is not used, because the rear struts have no upper spring perch.

Also, I discovered that by using only two o-rings per strut, the upper one would sit in the recess below the cartridge retainer cap and not provide sufficient positive locating for the collar, so I decided to use two at the top and one near the bottom. These are the medium-thickness o-rings from the coil-over kit.

I had to cut all the bellows off the stock rear boot to get it to fit inside the coil-over spring. Basically, it became a splash guard to prevent excessive amounts of water from getting trapped between the threaded collar and the strut body, which would eventually cause rust. In the stock setup, the boot is sandwiched between the bump stop and the cupped washer. Unfortunately, the cupped washer is too big to fit inside the coil-over spring, and the bellows part of the boot, although compressible, just gets in the way of the spring and would eventually rip anyway. Most aftermarket boots would be too big to fit inside the coils. I guess if you were really concerned about it, you could use a set of stock front strut boots, but the cupped washer would still have to be ditched in favor of a smaller washer.

I used a pair of washers that I found in my shop to take the place of the stock cupped washers. These particular washers had been used for sway bar mounting bushings, and so were already thick and wide, which is what you'll need. They were also slightly dished, which isn't necessary, but helps keep the bushing in place, provided you face the dished portion upward.
 

Besides being smaller in diameter, the coil-over spring also has its upper coil ground flat. Therefore, not only will the stock upper spring pad not fit, the spring will also not fit properly in the contoured upper perch.  The sheet metal of the strut tower is thin relative to the spring, and if the spring were to allowed to make direct contact, it could cause paint removal and rust, or possibly more severe damage, so I had to make some sort of vibration dampener. I ended up slicing a 5/8" heater hose in half, lengthwise, and cutting it to fit around the top coil of the spring. This is a compromise at best, and I learned later, when I removed the springs, that the hose had moved around some and gotten cut by the springs. A better solution would be to bond the hose to the coil with RTV silicone, provided the bond is allowed to set for at least 24 hours before installation. You could also use the upper spring pad that comes with the coil-over kit, but you'd have to cut a hole in the center large enough to allow the upper mount bushing and washer to pass through. I suppose a more permanent and ultimate solution would be to either fill the spring recess in the strut tower, or cover it with sheet metal, so that the flat coil would have a corresponding flat seat. In this case, a mere flat rubber sheet could be used for vibration dampening.

Installation is basically in the reverse order of removal, with some exceptions. As with the front struts, the rears should come with new piston rod nuts. You should use these instead of reusing the old ones, especially if the ones you removed had nylon inserts, as they lose their locking ability after they've been removed and installed a few times. You should avoid using an impact gun to install the nuts, as this has a tendency to spin the piston rod, and may not allow the nut to tighten properly. Ideally, you would be able to hold the piston rod with a wrench and turn the nut with another, but this is the real world, and of course, things don't work that easily. One advantage to not having the boots on the rear struts is that you can grab the piston rod at the upper bushing stop (where the washer sits, NOT the rod itself!!) with a pair of locking pliers and wedge it against the fender well while turning the nut from the inside. You can also try turning the nut down most of the way with an impact gun and then tighten it the rest of the way by holding the flats on the rod with a wrench, or pair of flat-jawed locking pliers. Whatever method you choose, just make sure you tighten the nut all the way down (when it won't turn anymore, it's properly tightened). If you hear knocking that sounds like it's coming from the rear fenders when going over bumps, it's probably an indication that you didn't tighten the rod nuts all the way.

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