Long time lurker, first time contributer. I've had the Dinan sway bar and camber plates and have decided to add shocks and springs. I wanted to do this install myself since I find this work quite enjoyable. I looked at several e39 web sites and nobody's written on this subject. Bentley hasn't come out with their e39 book yet either. I've had a fair amount of suspension experience with my e30 M3. How much different and how much harder can it be for an M5? Answers: a lot and a lot. Taking out the seats, rear deck, c-pillar trim and speakers are a little tedious but easily and quickly done. The hard part is getting the shock out of its control arm "cage".
Dinan sends a short instruction sheet with the package containing a few essentials such as where to set the lower spring perch on an M5 since this needs setting prior to install. Koni sends a few slips of paper in universal (read uninterpretable) picture language. I called the Dinan tech support line and they weren't very helpful. Frankly, they seemed to have no interest in helping. The local Dinan affiliated dealership made a good effort at helping but after trying things my way and theirs, mine worked better.
Tool requirements are pretty basic. You will need a spring compessor which can be borrowed free of charge from many auto part stores. The problem is that these are often bulky and antiquated. I have a nice, compact pair I bought from Autozone for $35. An impact gun is probably essential. I didn't try it without it this time, but in the past, I have been unable to remove the top shock nut ( the one that holds the shock mount) without an impact gun. Air tools are marginally helpful elsewhere but their bulk makes them difficult to use in the tight confines of the rear suspension.
Here are the steps I used as I remember them from three days ago. Please don't hold hold me responsible if you're dumb enough (as I was) to do this yourself and you end up screwing up your car or worse yet, causing injury to yourself. Torque values are not supplied with the kit but the best I can come up with a little research.
[list=1][*]Access rear shock mounts by following steps for rear speaker removal documented at the e39 tips and tricks website. Here's the address:
[*]Unplug the rear speakers first and then remove them complete with the plastic enclosure. They're held in by two Phillip's screws. Fold back the thick rubber insullation to expose the top of the shock unit. Go ahead and cut the insullation. It's easier than removing the seatbelt and a month later, you'll never remember you did this.[*]Jack up the rear, both sides. USE JACKSTANDS under the rubber padded jacking points. Remove wheels. (The Koni supplied instructions tell you to lift the car by supporting the rear wheels, but if you ask the Dinan tech line or the local mechanic about this, they'll act like your probably not qualified to even put air in the tires.)[*]Remove the 21 mm bolt from the bottom of the shock. The shock will slowly rebound and at this point you'll consider calling a tow truck because the shock is obviously not removable from the maze of control arms. Do not despair![*]Back at the rear deck, remove the three 13mm nuts holdiing the shock mount in place. Do NOT remove the central nut now.[*]The next several steps uncage the shock/spring unit. a) Remove the nut holding the sway bar to the link (16 or 17mm socket with a 16mm crescent wrench on the ball joint behind the bar) on both sides and rotate the bar down and out of the way. b) Remove the two 16mm bolts holding the caliper carrier to the hub and remove the caliper. Don't let it dangle. Support it with a gallon paint can. c) The ABS sensor cable will be in the way. Remove the 5mm hex bolt and pull the sensor straight out of the hub. d) Remove the 21mm nut holdiing the upper back control arm to the hub. Use a 6-sided 10 mm box wrench instead of the usual 12-sided wrench on the ball joint bolt or you'll strip this bolt. (The local dealership suggested I could avoid this step if the shock mount was left in place. I tried this by first compreessing the spring and then removed the shaft nut, but the shock mount was long enough that you could not push the bottom of the shock to the side and then expect the top of the shaft to slide out of shock mount.)[*]While pulling the control arm up and back, you can now wiggle the shock/spring unit out.[*]Compress the spring and remove the shock shaft bolt. (If you've ever wondered what a 4 inch hole in your chest would look like, don't compress the spring first.) Here's where an impact gun is necessary.[*]On the new shock, place the snap ring in the upper groove per Dinan's instructions and install the locking ring/spring perch. It's direction is that of an upside down cup. Add the stock lower spring pad. Remove the dense foam bump stop from the Dinan shock, place the supplied white plastic disk on the shaft and replace the bump stop. Place the stock metal bump stop cap over the shaft, add the new spring to the unit, then the new upper rubber spring pads and finally the stock shock mount. Screw on the new supplied bolt and torque to 26 ft.lbs. The new spring is short enough to not need compression. Hold the shock shaft on top with a 5mm hex bit. (I read somewhere on the messageboard problems occured because the Dinan spring was installed upside down. While the stock spring has a top and bottom, the Dinan spring is symmetrical end to end. I suspect the problem arose from the spring being improperly seated in its top perch or perhaps the new supplied perch pads were not used.)[*]In order to get a spring compressor in place, you'll need to remove the plastic wheel well liner. Do this now by removing three 8mm screws up front, three or four plastic snap screws in back, the two 10mm plastic nuts in the middle and the one rubber grommet on top.[*]Wiggle the new shock and spring into place, guiding the shock mount bolt studs up through the rear deck. Torque original nuts to 22 ft.lbs. I like to use blue locktite on these.[*]Compress the new spring with the spring compressor and with a lot of brute force, compress the shock until the bolt holes line up on the bottom of the unit with its mounting point. Replace the bottom bolt and use the new supplied washer and locktite. Torque to (?)92 ft.lbs.[*]Carefully remove the spring compressor so the top of the spring seats properly. You may have to compress and uncompress the spring a couple times at different levels and rotate the top spring pad for this to be right. The left side is easy. On the right side, the fuel filler pipe is in the way.[*]Reattach upper rear control arm, ABS sensor, brake caliper carrier, and plastic fender liner. Replace the sway bar attachments when you're done with both sides.[*]Replace the interior.[*]Per Dinan's instructions, check the rake once all four corners are changed out. You may need to adjust the rear perch height by moving the snap ring down.[*]A four wheel alignment is required, but from what I can determine, only the front toe is adjustable.[*]Drive. [*]Drive hard.[/list=1]
I'll add the front suspension install to this post once i"ve done it. Please feel free to add suggestions or criticisms. I have pictures, but couldn't figure out how to attach them to this post without having them hosted elsewhere.