Hey there everyone!
First of all - thanks to the many of you have helped me along in this process. As promised, here is a full write-up of my sub installation into my 2007 E86 M Coupe. Although technically this should work with the E85 as well, YMMV. All the wires should be the same for all E85/86 but please double check through BMW WDS if possible before committing to anything other than an e86 M Coupe.
Before we begin, this is a documentation of what I did. Legal disclaimer - these are not instructions and re not meant to substitute for professional installation. By using any of this information you agree to hold me harmless for any issues that may arise. Ok, that out of the way...
First the specifics...
I bought and installed the following gear:
JL Audio 250/1 Amplifier
JL Audio 10W3v3-2 Sub Speaker
The ideal spec for the box for the speaker I selected is .63 cubic feet. I ran some calculations and after all the math of the volume of the sub itself subtracted out, the plans attached here set it at that ideal .63 cubic feet! As a nice bonus to us Coupe owners, the sub fits perfectly into the nifty little shelf BMW made for it next to the battery cover.
Next, the key details for those that just want to jump in:
Initially received some info that turned out to be incorrect. After combing various sites, and ultimately with the assistance of a great guy from Belgium - GV (from z4um - BIG THANKS!) everything is squared away. Here we go:
Power - Direct from battery distribution block (see pic 15)
Ground - located within 15" from amp by scraping paint off to bare metal (see pic 18)
Amp Power Turn-on/Remote - thicker white wire, located in main amp cable bundle (tapped at yellow circle, pic 21)
Right Sound + Amp connector pin 23, blue with white stripe wire, heavier gauge (~18 ga)
Right Sound - Amp connector pin 22, blue with brown stripe wire, heavier gauge (~18 ga)
Left Sound + Amp connector pin 4, red with yellow stripe wire, heavier gauge (~18 ga)
Left Sound - Amp connector pin 3, red with brown stripe wire, heavier gauge (~18 ga)
* the heavier gauge note above is in comparison to the other harness wires. Most look about 24 gauge, but these are definitely easy to spot from the bundle. Also, I was given 3/4 and 23/24 - but my BMW WDS shows 22/23 - in any case, the colors are DEFINITELY correct, as they're hooked up. Pin's don't matter, because they're near impossible to see anyhow.
On to the install!
The pics are all below, but the narrative is as follows:
0 - all construction is done with 3/4" MDF, gorilla glue between butt joints, where two MDF boards touched on the faces, I used contact cement to get them to bond. Everything was then screwed using 2" coarse thread drywall screws.
Before starting on step 01 - I cut all the pieces as identified in my cut list (attached in PDF). I made some field mods, btw, but there is no reason you can't follow as it is shown for more crazy strength. For example, I skipped the right 'A' panel and added an extra E foot. The reason for these doubled up pieces (the ones at ab and cd) are that's where the speaker and amp get mounted. I wanted a solid underpinning. The rest are just for symmetry.
01 - First step , assemble sides b and f to make a perimeter box
02 - Glue with your favorite glue (I like Gorrila glue - as it expands to fill voids) and screw. I used a screw every 3-4 inches. MAKE SURE you pre-drill and countersink the screws. The pre-drilling is not an option - you'll bust the MDF if you don't. The countersink just makes it look nicer, the carpet will lump if you don't over each screw.
03 - Carefully trim and glue the top D panel and the bottom D panel. These go flush. Screw from the sides.
04 - build and clamp the base and feet - the base is c and e pieces. The E pieces are contact cemented together and then screwed (yes yes, I'm sure you're already thinking this... the only two things to survive a nuclear war, roaches and this sub box - they can live in it!)
05 -put box onto the platform, contact cement the two together and screw a few to hold together for now.
06 - mark the center (here you can see my 'few' screws - lol). These markings will be used to cut the speaker hole. Do cut the hole now. As you can see in the next frame, I added the additional A panel for amp mounting ane feet before the painting.
07-08 I painted the parts that would be exposed, could be exposed or could benefit from a hit of black with some flat black paint. (not that it mattered on the rear - I ran out of carpet!
09 - this is where a lot happened without pix. Basically I contact cemented audio carpet to the box, soldered leads to a terminal cup and reinforced it by gluing it with gorilla glue and using reinforcing MDF. The terminal cup was very flimsy and I didn't want it to flex with the bass waves. Here I also mounted the hooks from industrial Velcro on both feet. These are key - with this, the box needs almost no additional reinforcing.
10 - here you can see my crappy carpet shortage. This was the first time I learned that it's not like wrapping presents. Oh well - no one looks there. You can also see the gorilla glue leaking out of the terminal cup. This is on purpose to seal the cup area. Remember - sealed enclosure, means sealed!
11 - In all my research I've read that by using polyfill (dacron) stuffing in the box increases the bass depth. I can't tell if it did - I only did it one way. But since a 10" is the max I can fit - I'll take all the bass lows I can get. The recommended ratio is about 12 ozs per 1 cu ft in a solid enclosure. Since this one is about 3/4 of a foot - I used just a little less than the full 8 oz package (shown behind). BTW: I got this at a sewing store.
12 - This shows how the poly fills the space, but more importantly please note the JL gasket supplied with the speaker. It is critical this be laid carefully so it not bend or rip.
13 - The finished bottom.
14 - Open arse surgery begins. I'm 6' 4" tall and mostly torso, so it was a total biatch working back there. I took a skateboard ramp thing from my kids to be able to kneel 12" off the ground, and leaned over the trunk the whole time. My chest still hurts! Bring pillows! In this pic, you can see the Dice ipod adapter. It's ok - but it was cheap and easy to install.
15 - Here you can see my power leads hooked up to the battery distribution box. It is located between the battery and the exterior of the car in a covered box. There are channels in there designed to add additional cables, but I didn't have the right sized eyelet, so I paralleled an existing cable. Still, it's very clean, doesn't have to hang off the battery + post, because it's off to the side, it's part of the emergency disconnect and more. You can see the main amp fuse mounted to the rear of the battery itself. The positive cables run over the top of the rear firewall, I did this to keep the thick power cable away from the signal wires which run at the bottom of the firewall.
16 - another angle on the battery distro - cover is on now on the distribution panel
17 - mounting the fuse holder onto the supply cable - here is another angle showing the power wire running high
18 - make sure you SCRAPE ALL the paint, ALL the primer and then scrape the bare metal some more. This is where I drilled and mounted a screw and terminal for the ground cable. - note the DICE adapter for bearings.
19 - take two RCA cables, strip their ends, use splice connectors to add them to...
20 - the main wiring harness showing the connections. Please note - this is the way I did it first. THIS WAS NOT GOOD! See next pic...
21 - First I mounted close to the cable, but the second time (when I was given the right wires to use) I moved it to the yellow circle area. I also spread them out so as not to create a lumpy cable.
22 - see lumpy cable? This is why I moved from the red circle to the yellow. The angle that the harness bends made it a royal pain to put in this way.
23 - The cables are routed out as thus. Power is separate from signal all the way until we get to the amp.
24 - last shot before the box shows
25 - In the 24 pic and here you will start seeing a black bracket. It is an L bracket I painted matte black and mounted to the Satellite receiver bracket on the firewall. There is no way to measure it or replicate it - I had an L sitting around that I used. So just find a similar way to do this. It will keep the top of the box from tipping under acceleration. The velcro holds it overall - this is just stability.
26 - another angle
27 - cover comes on for the battery
28 - close-up of the amp area. Make sure you mount the amp in the fins up direction for optimal cooling!
29 - all finished 1
30 - all finished 2
31 - all finished closed, ambient lighting
32 - all finished closed, flash lighting
One key note - the carpet is a perfect match in reality. The issue is that the grade of carpet BMW uses is about 3-4 notches above this one. The nap is thicker and smoother (for lack of a better terminology). The color though, is dead on in reality.
So that's it. I have one more step to this crazy upgrade project. I am putting in MB Quart tweeters in the sail panels. I have no idea if these will work as a replacement as I don't have any resistance stats on the stockers. But If that goes, I'll document it while I go along and add a new thread as well.
The sound? Well - let's say it's the way it should have been. You just can't beat having all that moving air. It was worth all the hassle and headache. And as a bonus - for winter and wet driving... I just put about 60lbs over my rear wheels! If I want to go do a track day, it's 5 minutes... remove battery cover, disconnect main fuse, undo the two main screws on top of the sub holding it in place, disconnect wires and pull it out.
Ok, now going to soak my hands after all this typing. I spent weeks searching for just this sort of info. In the spirit of forums I hope it helps all of you a fraction of as much fun as I had doing it!