Ok, so you want a no frills but a great sounding sub install in the floor? I got you covered.


Listed below are the materials you will likely need.

I can’t tell you the tools you'll need because it will vary. You will find that you need some tools listed in the DIY below. Other than that, use your discretion on other tools needed.


Ingredients:

1 sheet of 3/4 MDF (Medium Density Fiberboard) found at Lowes/Home Depot.

1 can of 'DAP' all purpose adhesive caulk. Also found in the same stores.

1 box of 1 3/4" self tapping screws.

1 box of 'Grip Rite' drywall screws. I bought 1" which was borderline. 1 1/4 will be perfect. Also found in the same stores

4 yards of carpet. Found at Parts Express

1 can of 3M spray adhesive. Found at Parts Express

1 subwoofer. Found at Parts Express

1 amp.

6 feet of 12ga speaker cable.








First, remove the trunk floor. It may be velcro'ed to some parts of the trunk. It should look like this once removed:



Now place the trunk floor on the MDF board (which you should have already laid out) and use a pencil to trace the flooring. Make sure you do it along a far side of the board as much as possible to leave you more cutting in the future. Don’t pay any attention to the planks... it was some temporary ghetto bracing for the old trunk.



Use a jig saw to cut out your board. Go ahead and measure/draw lines to cut your board in thirds.



Once the board is cut into thirds. Use the jig saw to cut out the mounting hole for your subwoofer. Make sure it fits properly. Check for clearance. The sub I used had 5" of depth. Remember, you are going to also need to factor in that you will need 3/4" more depth for the MDF/bottom of your box.



Now stick the other 2 boards in to make extra measurements and proper fitting. If you want to get super technical, allow an 1/8" for the carpet. Cut/fit/trim if needed. That piece of metal was the screw mount for the spare tire. A hammer worked beautifully on that job.



Clamps will be your friend but you don’t have to use them. Start measuring the sides of the box and proper fit. I’m sorry, but I do not remember the measurements. I will warn you though the back of the trunk slopes up.



Now once the structure is built up, place the subwoofer in the box to check for clearance.




Return to your trunk to make sure the box doesn’t bottom out too bad and or lift up the edges preventing a flush fit on the top. It should sit on the sides and the bottom of the wheel well snug. If you are off about 1/8" on the edges, it’s no big deal. You will screw it down later so the board will obey to it.



Now take the box and sit it sideways on the MDF board so you may trace the cut-outs for the sides. I marked mine A and B for my reference. If you have cracks in the box, it’s not the end of the world. This is where the caulk comes in. THIS IS THE MAIN REASON WHY I RECOMMEND CAULK OVER LIQUID NAILS. IF YOU HAVE A LEAK, CAULK FILLS IT IN BEAUTIFULLY AND NICELY. Seal the box on ALL inside and outside cracks. Even if they look sealed do it anyway. Taking shortcuts on a box build will get you nowhere fast. If you would like to, you can get fancy and add wire terminals like you see. Don’t forget to caulk the crap out of the back of it!



Pull the box out and get ready to carpet it. Staple the carpet on one side only to start. Fold the carpet away from the box once stapled and spray the box with the 3M adhesive spray. Put the carpet on top and smoothen it out. Now pull on the carpet at a downward angle to get a tight fit and staple your way around it. Once done, trim if needed, only the top will be showing so it won’t be a big deal if anywhere else isn’t pretty. Do the same with the other boards too.



Now connect the sub, drop and screw it in. Place it in the trunk to make sure it looks right and centered. If it is off really bad, you’re screwed and you will have to start over.



Now screw in all 4 corners of the sub box with the self tapping screws. Make or get a T bracket and screw it in 3/4 below the surface of the box deck. This will be the middle support for the other 2 boards. You may screw them down if you would like to or not. It doesn’t matter. They should be a tight fit to begin with so they should hold in place.



You’re done!


Update: Finished Video