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Greetings folks! I am adding a subwoofer to my 2 door JK and wanted to do a write up. Let me preface by saying that I started this process by adding a 12" sub in a pre made, squarish box. It sounded good, but I missed having the expansive cargo space the two door offers so I decided to upgrade the "Premium Alpine" subwoofer to a Rockford Fosgate P3 (pictured). While this did sound good, it was no match for the 12", especially with the top off or even with the windows down. Therefore, I have decided to try my hand at making custom fiberglass composite boxes and utilize the cargo area in the trunk. As of writing this first post, it is not yet complete, so this is part 1, as I wait for the fiberglass resin to dry.

I began by making a 1.5" high square ring to serve as the attachment point between the fiberglass and the MDF top. It is important that finished height of the box not exceed 2" by much as the child seat anchors will impact it otherwise. My ring measures 30.5" by 13.5" outside. Next, I lined the entire cargo area with tin foil and used painters tape to secure it. I used two layers of foil. The fiberglass resin, once mixed with the catalyst only has a few minutes of drying time so you must work quickly. I used about a half gallon my entire project. It was advised that I use anywhere from 2-3 layers do fiberglass cloth for a filly supported box, and as many as 7 for a square, unsupported box, so I opted to use 4 layers. From what I understand, you must apply the resin liberally between the sheets and work quickly. I quickly found that the mat sticks to your gloves pretty badly after you get started, so, use your resin paint brush to refine the placement of the fiberglass sheets. After applying my 6 layers of resin and 4 sheets, I am now waiting for it all to dry. To be continued...
 

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I like it. I'm looking forward to seeing the finished product & your comparison of the sound w/ stock & your other 12.
 

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Discussion Starter #3 (Edited)
Part 2 of 3

So my first experiment with fiberglass went reasonably well. A couple of learning points:

1. Don't try to do more than 2 layers at once. I tried and 12-18 minutes working time is not enough to get it done. I should have done two, waited the two hours for them to fully cure and then done two more.
2. Use painters tape sparingly. The resin sticks to it very well and the it is rather hard to remove.
3. Invest in a "zoot suit" or something comparable. Fiberglass gets everywhere!

This morning I took my fully hardened box and ran a jigsaw along the top edge to cut the hardened fabric even with the wood edge. I sprayed the interior with primer to ensure there were no particles moving about in the box. I then cut out the top and, using a heavy bead of siliconized latex caulk I nailed and screwed the lid on. I then filled the cracks from the outside with more caulk and primed the entire box. I didn't have time to carpet the enclosure today, but should get that part finished tomorrow. I am about 2 hours invested so far with setup and actual work. Part 3 to follow tomorrow!
 

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Part 3

Project complete. This enclosure hits a lot harder than the wood enclosure I had first and definitely outshines that puny 8" in any configuration. I am very happy with the way this turned out. :bounce: It is plenty enough bass to turn it up on the highway with the top and doors off. I ended up having to pull the cargo area liner out to get the seat to latch, so it is about 1/8" too tall. Make sure you get the stickiest spray adhesive you can when you go to carpet the box. I tried to use the less sticky stuff last time thinking I would have more time to manipulate the carpet over the box. It completely let loose the first time it was rained on. I used the sticky stuff this time.
 

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Looks good. How tall above the floor is your box? Looks like maybe 2" or so?
 

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It's about 2.25" tall, which is a little too tall. I had to,remove the plastic liner in the cargo area to get my backseat to latch. :flame:
 
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