Removal and Replacement of Rear Shocks/Struts
The rear strut is pretty easy to remove and replace. In my case, I came across a set of used Bilsteins that were the perfect replacement for my creaking, sagging rear suspension. The good news is that when we pulled the Bilsteins off the 745i donor car, we pulled the entire cartridge out (including springs and mounting strut), so it was merely a question of switching them out.
Note:
*You need a lift to perform this operation
*I also recommend having a buddy around to help you pull down the old shocks and mount the new ones.
To get to the top bolts of the struts, you will need to remove the rear seat.
Use a phillips screwdriver to remove the two screws underneath the seat. Once they are out, you should be able to lift the bottom part of the seat out and set it aside. Then remove the bolts holding the seatback to the frame of the car. To access these, pull down the middle armrest and push the leather cover aside to reveal 3 bolts.
Once these bolts are removed, lift up and out to pull the seatback away from the frame. Be careful and don't force anything, you don't want to put any tears in the leather. With the seatback removed, you can lift the flat panel behind the seat up to reveal 3 holes in the frame giving access to the strut nuts (which are actually in the trunk compartment, but are much easier to access this way). See below:
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Each strut has three 13mm nuts; use a socket with a 6" extension to undo the nuts and then use a magnet to extract them. |
| With the car up on the lift, place a scissor jack beneath the strut to support its weight once it comes free. Then use a 22mm socket and an impact gun to remove the bolt holding the strut to the wheel. | 
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Take a look at the shocks which came out of my car -- the KYB shocks are OEM, so they're probably original. The springs must have been totally shot, though, because someone (the previous owner or more likely his mechanic) actually took the time to fit spacer clamps to the springs in order to squeeze more life out of them. This seems like a pretty strange solution to me; not only does it have the effect of lowering the car and reducing the performance of the springs (in an attempt to stiffen them up), but it doesn't look like it would have been an easy thing to do anyway, given the difficulty of compressing the springs. Why would you go to the trouble of removing the strut assembly from the car just to implement this ghetto fix? Why not just put new springs on? Dunno... |
Putting the new shock cartridge on the car is a two-man job. One of you needs to feed the 3 strut bolts into the top frame mount; the second can sit in the back seat of the car and once the bolts come up through the frame, get the nuts finger-tight on them so that the frame is holding the shock in place. Then get out of the car and fit the 22mm bolt back into the bottom end of the shock and line it up with the wheel. One of you may need to pull down on the wheel while the other pushes up on the shock in order for these to line up.
Use your impact gun to tighten the 22mm bolt, then climb back into the passenger compartment to tighten down the 12mm bolts at the top of the assembly.
| The new shocks in place... |  |
Now put the rear seat back in (installation is of course the reverse of removal) and test out your new rear suspension. Coming soon; Front suspension replacement.