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Old 10-25-2011, 09:23 AM   #1
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Join Date: Nov 2010
Location: Baltimore
Posts: 1,449
My Ride: '01 325xi, '90 325iC
Custom Rear Deck Dual 12" Subwoofers! [+ build pics]

Hey fellas, ever since i saw that amazing Image Dynamics sub in 95SeriesBMW's rear deck, I was dying to throw one in my car. Problem was, that sub was a wee bit expensive for me lol

Here is where my journey began: one sub, in a white box, in my trunk:

I thought I was pretty clever with the placement of the AMP under there rear deck:

When I started this box, it was during the winter, so due to the cold weather, I figured I would just make a small temporary box until spring break when I could unleash my fabrication skills! Well, spring came and passed, and this ugly puppy was still in my trunk....

The day I got out of school for the summer (was summer after sophmore year at the time) I decided to begin!

Initial plan:

Then I figured...well if I am going to legitamently do this, I might as well go big eh? Why not two i thought?

So I ordered up my other sub, and a new amp to power both of them! These are two 12 inch RE Audio SE-X 12 Subwoofers, each putting out 600RMS, 1200 peak. The amp that replaced my older 1000 watt amp, was a new HiFonics 1500 watt mono sub amp.

Next, I decided what shape I wanted the box to take in order for this to actually happen. I decided on a box with a slanted top so the exposed subwoofers would peek through slightly tilted towards the cabin. The whole point of this endeaver other than crazy looks, was to increase trunk space (well.....that didnt happen lol cuz I have 2 subs inplace of 1), but nonetheless, I decided to make the box suspend from the rear deck to allow items on the trunk floor. I figured the bottom would be a larger rectangle to allow sufficient interior area. Next I cut out the two 12 inch holes for the top piece of the sub. I forget the measurments, but after I had that roughly done (i know the holes are not 100% circular in this pic, but I was getting antzy, so i finished sanding them at the final stage). Anyway, then I cut out a rough area from the rear deck. (no turning back now!)

I then made a "mock" box with sides just to test the fitment into the hole i had cut. Keep in mind this was after tons and tons of sanding, and dremeling:

Seemed to work well, and best part was, it was so snug that it was practically held in place that way (turned out that sucked alot during installation lol). Now for the support, I figured I would do something with corner "L" brackets of some sort. More on that later.

Now I decided to pull the trigger on the actual box. So after measuring once and cutting twice () I ended up with this bad boy (not secured to each other yet except the top):

Happy with my design, I screwed it together WITH SOOO MANY SCREWs! omg, i ended up going with 1 screw every 2 inches. OVERKILL Of course, I used wood glue and caulk afterwards. Final result:

Yay, looking good. Next I had to go to Ocean City for two weeks, so i mounted it in, and took a vacation with my BMW with no rear deck or rear seats Here is how i braced it in! Oh, and this was so ing hard to put it with the subs actually in it. Ended up haveing to use a combination of bricks and my OEM jack to get it into place lol.

Dont have a picture of this, but i have 4 brackets in the trunk also securing it (pics of it on finished product later)

No pics of this, but i makeshift threw my amp in the back and hooked it all up. Boy, It bumped! But there was a really obnoxious rattle of the wood squeaking against the sharp metal of the rear deck.

During vacation i ordered some matching trunk liner from not sure, but something along those lines, under 5 dollars for 4 yards or so. Matched the color well, also got some HIGH QUALITY interior black auto felt to recover the rear deck, which i WILL be reusing That was almost 30 dollars, but well worth it. Here is a shot of the box fully carpeted. I used 3m 77 adhesive, and alot of it:

(yeah looks sloppy from this view, but thats cuz you never see this angle upon istallation)

Whuddup! Finally coming together. At this time, here's what I still had to do: the interior rear deck + sound dampening etc, and the amp + wireing. I decided to do the later cuz i was scared shitless of doing the interior lol

Decided to secure the amp to a piece of MDF secured to the back of the rear seats. No mine do not fold down......this was a huge pain in the 100+ summer days.... thanks for those record temps baltimore.....

But first, i must make the wireing neat. Here is something i like alot:

Last edited by TR4G-; 10-25-2011 at 10:54 PM.
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