Since this whole process took me multiple days to complete, I'll group it as such here...
Most of the suspension bits arrived today. I ordered the H&R Coilover kit from Evolution Sports on special for $1280 with free shipping. Also ordered 15mm H&R spacers, guessing that I may need them. The Rear Shock Mounts with reversing plates also arrived from JT Designs. Opening everything was like Christmas...
Looking in the box it's like, "Wow... all this shit cost me $1280." Doesn't seem like much stuff for that much money. :-) If you'll notice the dealie between the rear shocks, and the one that the rear spring is sitting on, those are the ride height adjusters for the rear that no one seemed to know whether or not they really existed. Evolution Sports didn't know. They called H&R, who didn't know. I called H&R, and he was unsure as well. Their website says the rear is adjustable 1.25 - 1.7 inches, and then right next to that it says, "Note: Height adjustable only at the front axle." I even had someone who ordered the kit just a few months ago tell me it wasn't ride height adjustable. I think I've figured this out: Over a year ago H&R converted the kit to having ride height adjusters in the rear. However, I guess Tire Rack had a whole bunch of these in stock from the earlier kit, without the ride height adjusters, and they were still selling them until recently where I think they have finally sold out. So, people who purchased the kit recently from the Tire Rack got the old kit without the rear adjusters. Anyway, they seem pretty slick.
I totally guessed at the spacer size I may need, judging from what kind of clearance others have. We'll see if it's the right one (if I need it at all) once I install the kit. The naming scheme for these things on the box is weird... it says 30mm on the side. I was thinking, "Oh great, they sent me the wrong ones!" But I checked the part number, and it was correct, and they do measure at 15mm each. It's as if they measure the combined width.. go figure.
I decided to take apart the rear area of the car today instead of trying to do it the day of install. Everything was fairly straight forward until I got to the B Pillar. I removed the seat belts, and supposedly the B pillar cover just slides up... well mine didn't, on either side. I simply could not remove them. They really need to be removed to access the screws that attach the trim piece that goes from the B pillar back to the hatch, right below the window. When trying to remove the first one it seemed as if maybe it was just clipped down so I started yanking on it, and it did come out... once it was in my hand, though, I noticed there were little tabs all around it, where it met with the B pillar, that had broken off. It is also screwed in towards the front of the car, and I broke the hole the screw goes through. Bummer. When on the other side of the car I realized that you don't really have to remove the piece. If you just pull up on it fairly hard, you can access the last expansion rivet holding the carpet piece in, stick your screw driver in it, and remove it. Wish I figured that out first. Oh well. Other than this everything was pretty straight forward. A useful resource may be Ron Styger's post about removing the trunk trim. In the end, it took me 2 hours 45 minutes to have access to the RSMs. This would have been cut down to under 2 hours if I had known I didn't have to monkey with removing the B pillar cover and rear-ward trim piece.
The day of the installation. I found a couple of excellent resources for installing suspensions in the 'coupe, but none specificly addressing a coilover kit. (UPDATE: AFTER I finished my install I found a great document put together by someone detailing the install of an H&R Coilover kit in his E36 M3. This should be very similar, if not totally the same as our cars. This would have been very helpful had I found it previously.) Things are very similar, so I figured everything would be okay. AndyM has a very thorough writeup of the install posted on bimmerfest. It's the main document I went by, but there were a few differences and problems I encountered that I'll point out. Shawn McCurdy also has a decent writeup.
I did the install at my friend Roy Lewis' house. We started by jacking the rear of the car up and tackling the rear. This seems pretty straight forward. Be sure to keep the car in neutral so that you can lower the rear swing arm as much as possible. This makes getting the rear springs out very easy. Many people complain about having to pry them out for 15 minutes, but for us they just popped right out. With the Coilover kit, you reuse the upper spring pad, with the rubber nipple on it. You do not reuse the stock rubber lower spring pad, though. Just remove it and clean off the metal fitting. The ride height adjuster then sits right on top of the bump. Confirm that it doesn't have much play, but mine did rock around a bit even though everything was perfectly clean. There are three alan screws along the base. Leave these loose for now, and install the spring. Once we put the spring in and put a bit of load on it (by jacking up the swing arm), I tightened the alan screws down.
Next we made a real bonehead move. We finished installing one side of the rear and went on to the next. After both sides were done, I jacked the swing arm way up to see the spring compress. When I did this the shock shaft went shooting up into the hatch area.
Now why the hell did that happen? After looking at it for a bit, I figured out what we did... We put the washer that came with the new shock on top of the new RSM, replacing the washer from the stock ones... leaving no washer on the bottom side of the car. Do you see the problem here? There was nothing left for the shock to push on on the underside of the car, so it just shot right through into the car. Damn good thing we figured this out before we lowered the car. That could have sucked. You may be able to see the lack of a bottom washer in my premature "finished" photo:
Speaking of those rear shock mounts, I took some Goop (glue) and placed it on the underneath side of the reversing bracket. This way if I am ever to swap out the rear shocks I won't accidently push the bracket into the car, thus requiring me to take the interior of the car apart (the whole reason I bought these things was to avoid doing that again). With the screw-ups, the rear took 3 hours total.
Okay, on to the fronts... the fun part. Without really thinking about what would happen, I decided to jack the front corner of the car up while keeping the rear on jack stands (because I had planned on removing the pads to put anti-squeal on them). I jacked the right front up, placed the jack stand underneath it, and removed the jack. I began hearing a sound... sounded like the left front tire was rubbing on the ground. But how could that happen? I even said, "What's that sound?" Then the car starts shifting, and the whole thing starts coming towards me. I hear it go tink-tink-tink... and look to see what happened:
Yup... it had settled itself on the three jack stands, leaving the left front wheel up in the air! Kind of cool, really (considering it didn't fall)... Still, I quickly put the jack under the left side and put a stand under it. AndyM's instructions were good on the removal, except he fails to mention you have to disconnect the front sway bar from the strut. Perhaps it's different on the Z3 Coupe? Who knows, but it's not like this missing instruction matters because everyone would realize they couldn't get the front strut out without disconnecting the sway bar! But removing the struts was pretty straight forward. Once out, Roy got to work compressing the stock spring and removing it. We could only get the compressors around two coils on one side, so it caused one end to compress a hell of a lot more than the other. After everyone pounding into my head how dangerous these things are, and not being the one actually doing the torquing on the wrench, it freaked me out a bit. I was waiting for one of us to get impaled at any moment. But fortunately for our guts, that never happened. Below you can also see the stock spring compared to the coilover spring. Quite a bit shorter and smaller, huh?
Next came the truly fun part... assembling the new coilover struts. I used all the parts from the stock hats. Since the stock spring was so much larger than the new one I was wondering how the spring would seat on the spring plates, so a few days before the installation I called H&R. The droid on the phone told me that I don't use any of the lower stock strut assembly, just resting the spring directly on the ride height adjuster. I said, "Okay, what about the top?" And he says, "You use all the stock parts on the top." I said, "Okay, so from the upper spring pad and plate on up it's the same as stock?" he said yes. We tried to assemble the first strut like this, but clearly it was not working... The spring just could not possibly seat correctly on that plate, since it was contoured to the stock spring. Here is the bastard strut we were able to assemble:
Clearly this is not correct. The spring does not seat well on that upper spring plate at all. Quite obviously the instructions the guy at H&R gave me were incorrect. But what else were we to do? I looked around online for any instructions on the install and found none. I went back to Evolution Sports' website for this kit and looked at their pictures.
Ah ha... Indeed, I was clearly missing a part. As you can see in the picture above, there is a black plate that sits on top of the spring. This replaces the stock upper spring plate. Luckily Evolution Sports is open until 7pm on Saturday, and I called them around 6:40. I explained that my kit did not include this piece. He apologize, and said that they were closed on Monday, but that he would call H&R from home on Monday and have them next day air me the missing parts. What a disappointment that both companies had failed to notice that the pieces were missing. Also a disappointment that the guy at H&R told me the wrong instructions so I wasted hours trying to figure out how to assemble the strut with the stock plate, not knowing that I was in fact missing a part. What a drag. Well... there wasn't much else we could do with the install until those parts arrived, so it was time to close up shop until Tuesday. The Porterfield R4S pads I put on my car a few months ago were screaming like mad ALL the time, so after the stall on the suspension install, I removed the brake pads, applied some anti-squeal, let it get tacky for a few hours, and put the pads back on.
The H&R upper spring plates arrived today. I went back up to Roy's after work to finish the job. The tricky part with the coilover springs is that since they are so much thinner than the stock springs, they will not fit over the strut when the spring compressors are on. So, what I did was compress the springs as much as possible with the spring compressors while the spring was off the strut, hold it down with zip ties and locking pliers, and then remove the spring compressors (though I couldn't remove one of the ends since the spring was now compressed):
Next it was time to transfer this to the strut. I put the spring over the strut and realized that I didn't compress the spring enough (though I did go just about as far as the compressors would allow me). I used some locking pliers to compress them the rest of the way. I just love this picture... this, my friends, is the proper way to assemble a strut. I read it somewhere... probably...
Crude? You know what, it worked. It did leave some marks on the spring, but so what? The struts are hidden and the marks are only visible under close examination. Once the spring was compressed enough I put the hat on, tightened the bolt, removed the pliers and cut the zip ties. I was left with a beautiful, much shorter than stock, strut! I hit the repeat key for the second strut.
And into the car they went.
Everything was torqued down, and it was time to try and fit the wheels... and...... Bummer! The wheel most certainly hits the strut! And it's not close, either. It's not like it would barely be rubbing.. it would be grinding against the strut. I opened up the 15mm spacers and slapped them on there, and put the wheel on. This seemed to be just the perfect size. Good guess. It clears the strut by probably 5mm or so. Too bad I had to use it, but *shrug* Oh well. The car was lowered from the jack stands (this time the whole front at once!) and there it sat... lower than before. If you'll notice where we had the ride height adjusters set in the pictures above, the front is at the lowest possible setting and the rear is near the highest. This is just what made the install easiest. The front certainly looked low, and the rear looked just like stock (and even measured just like stock). So if for some silly reason you wanted to keep the stock ride height, you could probably do so with this kit. I took the car for a quick drive. I have heard some people say that coilover kits are a bad idea for street cars because the ride is so harsh so I was really expecting something shockingly different from stock... the first thing I noticed though was that the ride comfort was very similar to stock. However, it seemed a bit more precise going over bumps (and that lovely washer board on Roy's gravel drive). The front was certainly too low, though, as I noticed it rubbing pretty good over some large bumps. I went back to the house and we dropped the rear 3/4" or so and raised the front about the same. This actually left the rear now lower than the front, which is exactly what I wanted to avoid with the H&R spring/Bilstein shock combo. Oh well, it was late and I had to head home. Getting the front in took 6 hours, and that's including our hour trying to fit the struts with parts that didn't make sense. Fiddling with ride height could be done another day.
And of course that day was the next day. After looking at the car I decided that the front had to be lowered a bit more... I set it about four threads up from the lowest setting, which looked perfect. My initial drive showed no rubbing, so I was content. I then decided to measure and set my toe. I did some reading and there doesn't seem to be a consensus on this (as with anything). As with most street cars, the 'coupe is generally setup with toe-in, for understeer. I think around .2" combined. I saw some people saying that they run up to 1/16" toe-out for the street and get no adverse tire wear problems. I measured my toe-out to be 1/8" combined... but this is with toe plates that take the measurement a few inches outside of the tires, whereas the measurement is usually taken at the wheel rim. So this figure is a bit exaggerated. I figured I'd just leave it and see how it drove.
This morning I got pulled over and issued a ticket for driving without a front plate on my car. Fantastic. Having cops on front plate patrol is a great use of my tax dollars. Anyway, in the evening I finally had time to put the interior of the car back together. To try and eliminate some of those damn rattles, I got some sheets of felt that are thicker than felt tape (which I couldn't find) and sticky on one side. At first I wasn't sure it would be a good option, but it was all I had...
After working with the stuff for a while I decided that it was a much better option than the felt tape stuff (which the local dealer used to try and eliminate rattles last time, and failed) because it's thicker and therefore separates the rubbing plastic bits more. The main offender of rattles is the three piece plastic partition directly behind the seats. This thing creeks like crazy! The two side piece have to be off for the install. I opened these suckers up and put felt over every surface that touched another plastic surface. Totally covered up all the screw holes with felt, as well as all the edges and interlocking parts. These suckers were felted out. But wow, what a difference! Where as before I would hold and squeeze the pieces and they'd creek like crazy they no longer made a peep after I feltified them! The larger center piece is a bit tricker to access because it bolts on underneath the center console. I was able to get it apart and work on it while sitting in the hatch, though, and applied the same, though slightly inferior treatment. Creeks are now greatly reduced in this area. I also removed the plastic trim around the actual hatch (on the bottom), as it creaked like mad when I leaned on it, so it must creek when I drive. Time will tell how these solutions hold up, but so far it's promising. Since I did all this extra work to try and silence the car, reassembling the trim probably took 3 hours.
I'm going to call the suspension officially done today. After just driving to and from work I made a final adjustment to the rear ride height and went for my first real drive this morning. The car felt fantastic! Anyone who says that Coilovers are too rigid for the street is too old to be driving a sports car! This car feels the way it should now. Going over bumps and railroad tracks it is MUCH less bouncy and much more comfortable than stock. If the road is really uneven (with concrete patches or something) then things do get a bit bouncy, but nothing to really complain about. Overall the ride comfort is actually improved over stock form. Besides this, the car feels totally planted in the turns. A few months back I drove my friend's new Mini Cooper S and was disappointed because the suspension on the Cooper was so much flatter than my car, with much less body roll. I tell you what, I no longer envy the Mini. This thing is ridiculously flat in the turns. It feels totally planted to the road. In Portland there are lots of sweeping freeway overpasses, ramps, and bridges where there are expansion joints every few hundred feet. I really didn't like taking these turns fast in stock form because over each one the M Coupe kind of skipped over them, jumping to the side... really unsettled the car. Over the past couple days I have flied through these same freeways and the car isn't unsettled at all. You barely feel the joints at all; you just hear them. It's fantastic. Another thing I noticed is that so far, all hints of understeer are totally gone. This car use to understeer through turns all the time during enthusiastic driving. While this probably isn't entirely eliminated, it's certainly greatly reduced. Much of this is probably attributed to the toe-out, which I do think I will keep as it is.
In the afternoon I went over and drove a friend's M Coupe who has just H&R springs (stock shocks). We drove each other's car back to back down a great stretch of tight road. I took my car first and was really loving the way it handled the turns, but I was pushing a bit harder and I was getting rubbing in the front, sometimes pretty bad, through the tightest turns. At the end of the road we switched cars, and I took the rear, following my car. I've been in this car on the track before and even with just the springs I noticed there was significantly less body roll than my stock car. However, driving it now I now noticed there's quite a bit of body roll and transitions aren't nearly as nice as they are in my car with the Coilovers. The car is so flat now that transitions really are smooth... that's something that has always been a problem with the stock M Coupe. It was cool watching my car in front of me, taking these tight turns and staying almost totally flat through them. Looked great! Arriving back at the house I grabbed a quick picture.
I'm going to have to figure out what I'm going to do about this rubbing problem. Other than that, the car drives amazingly well, and I like the look of the height right now. So I don't want to raise it. I believe it's only rubbing in two spots... in the center of the wheel well towards the front of the car, and on the lip on the outside of the plastic wheel well.
This is just plastic, so it's not going to hurt anything if I just leave it, but it sure does suck. I'm thinking of just cutting back the plastic wheel well a half inch or so. This should eliminate the most offensive rubbing and probably won't have any adverse effects. I'll have to remove the wheel and investigate a bit further.
This is a fantastic upgrade and I would recommend it to anyone. I was a bit hesitant to spend the cash on it, but I'm really glad I did. Besides the great improvements in performance, the ride comfort is top notch and the adjustability of the height lets you dial in just what you want. So far I'm very happy with it. The real test will come at the next track day... Can't wait.