Definitely a great thread; good remarks from everyone. I just installed a PSS9 set on my 2003 M5 and have a few remarks to add to those mentioned thus far.
1. Bilstein's instructions do not indicate in their parts blow-up or in their non-existent text the "plate" P/N 31 33 1 096 068 which acts as a stop for the rebound bumper portion of the upper strut mount. This part definitely needs to be reused (no need for a new one) and included as part of the front strut assembly! Without this plate, any rebound is going to be absorbed by the mount rubber at the metal sleeve where the strut's threaded shaft protrudes thru the mount instead of onto the body of the strut mount's rubber slug, surely resulting promptly in a failure of the upper mount.
2. The two OE parts indicated for reuse on Bilstein's instructions for the Fr. struts are not indicated quite as clearly as they could be. The strut mount itself is of course the strut mount, and it looks like one, but the plate below it that looks like a shim is in fact P/N 31331090612; the axial cage bearing, necessary to allow turning of the strut for steering. It comes (from BMW via RealOEM.com info.) as the "UPPER SPRING POCKET W/AXIAL CAGE BEARING" but the pocket portion is replaced by Bilstein's own upper spring perch. Insert the old (or new, why not) bearing into the underside of the strut mount and away you go . . . .
3.The front strut can be installed in any orientation (i.e.: decal in, front, or out) but the real decision to make on this is how you want the adjustment dial to face. There is a hash mark on the fixed portion of the dial which is useless if you face the 180 degrees of dial travel in towards the brake backing plate. Counting and recounting clicks back and forth from the stops at "1" or "9" in order to make sure you are on "5" or "7" or whatever is tricky and not immediately conclusive since the click detents are shallow, they are closely spaced, and the drag on the dial is high. Face the strut so that whether you are going to be making adjustments from on a lift, or on the ground from from behind or in front of the wheel, you can see what you are doing. The car itself doesn't mind nor will know how the strut is aligned.
4. On the rear shock replacement, I did not need to remove the plastic wheel arch liner. I did uncouple the "wishbone" (it's certainly not a forked 'wishbone' but that's what they call it . . . .; it is a 'rear upper link') P/Ns 33 32 6 767 831 / 832 for L & R at the outer ball joint where it connects to the wheel bearing carrier and pulled it back and upwards to give clearance for removal and installation of the shock. Additional benefit is that if the inner bushing or outer ball joints are at all soft or loose, you can tell that this is a good time to replace the link. The adjustment dial on the Rr. shock only can face the one good way; no choice here. The rebound bump plate is indicated here, properly on the top of the mount under the top lock nut.
5. Disassembly of the rear parcel tray behind the rear seats, necessary for access to the Rr. shock mounts is only a pain. On my car, the wiring for the R. Rr. speaker was seriously frayed where it passed under the frame from the wiring harness bundle (running along the side of the rear seat bolster) to the speaker itself. It was a simple matter to thread it back out to the point it leaves the harness, repair it, and reinsert it where it wants to go. The frame underneath which it passes has a sharp edge which is not good for wiring but there it is. I made sure there was plenty of slack in that area and that the twisted wire pair was not in contact there. Once installed its not going to shift around much if at all (?!) This was the only mal-designed part of the entire car, shock set-up or installation process that I noted during this job. The E39s are definitely heads and shoulders above the E34s in this respect, as well as most if not all others.
6. My PSS9 set seemed to come pre-set for stock ride height. Whether this was by chance or design I do not know but it was a very good place to start from. I ended up lowering the car 1/2" Fr. & Rr., not much by design as much as in making sure the L & R side ride heights were equal after fiddling with the units immediately after taking them out of the box. It might be wise to avoid monkeying with them at all and making sure the perch locks are locked before installation.
7. ENJOY!
1. Bilstein's instructions do not indicate in their parts blow-up or in their non-existent text the "plate" P/N 31 33 1 096 068 which acts as a stop for the rebound bumper portion of the upper strut mount. This part definitely needs to be reused (no need for a new one) and included as part of the front strut assembly! Without this plate, any rebound is going to be absorbed by the mount rubber at the metal sleeve where the strut's threaded shaft protrudes thru the mount instead of onto the body of the strut mount's rubber slug, surely resulting promptly in a failure of the upper mount.
2. The two OE parts indicated for reuse on Bilstein's instructions for the Fr. struts are not indicated quite as clearly as they could be. The strut mount itself is of course the strut mount, and it looks like one, but the plate below it that looks like a shim is in fact P/N 31331090612; the axial cage bearing, necessary to allow turning of the strut for steering. It comes (from BMW via RealOEM.com info.) as the "UPPER SPRING POCKET W/AXIAL CAGE BEARING" but the pocket portion is replaced by Bilstein's own upper spring perch. Insert the old (or new, why not) bearing into the underside of the strut mount and away you go . . . .
3.The front strut can be installed in any orientation (i.e.: decal in, front, or out) but the real decision to make on this is how you want the adjustment dial to face. There is a hash mark on the fixed portion of the dial which is useless if you face the 180 degrees of dial travel in towards the brake backing plate. Counting and recounting clicks back and forth from the stops at "1" or "9" in order to make sure you are on "5" or "7" or whatever is tricky and not immediately conclusive since the click detents are shallow, they are closely spaced, and the drag on the dial is high. Face the strut so that whether you are going to be making adjustments from on a lift, or on the ground from from behind or in front of the wheel, you can see what you are doing. The car itself doesn't mind nor will know how the strut is aligned.
4. On the rear shock replacement, I did not need to remove the plastic wheel arch liner. I did uncouple the "wishbone" (it's certainly not a forked 'wishbone' but that's what they call it . . . .; it is a 'rear upper link') P/Ns 33 32 6 767 831 / 832 for L & R at the outer ball joint where it connects to the wheel bearing carrier and pulled it back and upwards to give clearance for removal and installation of the shock. Additional benefit is that if the inner bushing or outer ball joints are at all soft or loose, you can tell that this is a good time to replace the link. The adjustment dial on the Rr. shock only can face the one good way; no choice here. The rebound bump plate is indicated here, properly on the top of the mount under the top lock nut.
5. Disassembly of the rear parcel tray behind the rear seats, necessary for access to the Rr. shock mounts is only a pain. On my car, the wiring for the R. Rr. speaker was seriously frayed where it passed under the frame from the wiring harness bundle (running along the side of the rear seat bolster) to the speaker itself. It was a simple matter to thread it back out to the point it leaves the harness, repair it, and reinsert it where it wants to go. The frame underneath which it passes has a sharp edge which is not good for wiring but there it is. I made sure there was plenty of slack in that area and that the twisted wire pair was not in contact there. Once installed its not going to shift around much if at all (?!) This was the only mal-designed part of the entire car, shock set-up or installation process that I noted during this job. The E39s are definitely heads and shoulders above the E34s in this respect, as well as most if not all others.
6. My PSS9 set seemed to come pre-set for stock ride height. Whether this was by chance or design I do not know but it was a very good place to start from. I ended up lowering the car 1/2" Fr. & Rr., not much by design as much as in making sure the L & R side ride heights were equal after fiddling with the units immediately after taking them out of the box. It might be wise to avoid monkeying with them at all and making sure the perch locks are locked before installation.
7. ENJOY!
