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Fiberglass in hatch

8545 Views 29 Replies 5 Participants Last post by  GarryGraves
Over the past few months, I've tried about 6 times to build myself some fiberglass enclosures to sit on both sides of the cubbies in the hatch. Needless to say I failed each time, and the serious lack of information on the subject coupled with frustration has led me to almost give up all hope of ever getting the huge box out of my hatch while keeping my bass. So what I need from y'all is one of three things:

1. A dumbed down walk trough to working with fiberglass
2. Somebody to build the molds themselves for me
3. Approval to use the existing plastic panel as the base of the mold itself

Any info or help would be greatly appreciated, this is the home stretch to finishing my interior once and for all.
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Yes, you MUST use fiberglass mat. I haven't done any fiberglass either, but I plan to (attempt to) build an enclosure for the side of my cargo area.

Here are several online tutorials that I've been studying. Of course each is basically showing the same process, but some things are shown/explained better in different tutorials.

Step By Step Fiberglass

Building a Fiberglass Speaker Box

Building my own custom sub enclosure for cubby-holes -

Fiberglass subwoofer box - a tutorial
Follow question for you Greg (since you seem to know what you're talking about):

I am trying to figure out the best way to fasten an enclosure to the car. I've seen a few places recommend industrial strength velcro. I'm worried that may not be strong enough. I don't want it to become a deadly projectile in an accident. I know the factory (Bazooka) sub installation calls for cutting a hole in the plastic to gain access to a nut welded to the inside of the quarter panel. Do you think it would work to put a piece of mdf on the back where the nut is and glass it in, then drill a hole in the mdf to bolt it down? I'm guessing I should use a rubber washer on the bolt head to seal it since I want a sealed enclosure.
I'm not clear on where you are wanting to glass the mdf to though.
When I find exactly where the nut is I have to cut/drill a hole in the plastic panel for the bolt to go through. Then I put the tape and/or foil in the cubby. After I put on the first layer or two of mat I'll put a piece of mdf (maybe 4"x4") over the bolt access hole, then as I add more layers of mat I will go up and over the edges of the mdf so it is incorporated into the enclosure. I'm hoping that will be strong enough to hold the enclosure in place after I run the bolt through the mdf and into the nut on the quarter panel.

The only other places I can see to possibly bolt it down would be to extend the fiberglass to where the 2 D-rings are (like 2 small fiberglass wings). I could unbolt the D-rings and refasten them over/through the fiberglass. I don't think that would be as strong though.

Thanks for all of your advice :grin:
Alright guys so I gave it another go and tried the right side cubby again. 4 layers of resin/mat/resin/mat seems to have given me quite a sturdy box. I pulled the mold out and gave it a decent stress test and it seems pretty stable. I started on the left side cubby and it's still drying as I type so hopefully that one comes out just as good. Tomorrow I'll be trimming the enclosures and ordering the mounting rings. Now I just have to decide which direction I want to mount them, so far straight up seems to make the most sense. Also Greg, I have no idea just how strong fiberglass is by feel, so my confidence with these enclosures holding up at full volume is getting me a bit worried, can I drill out a small hole on each one and do like a fake vent/port to relieve pressure or should I just have confidence 4 layers will be sturdy enough? It's sturdier than the plastic cubby is though, I can tell you that much.
So I'm going to add here, even though I may not know 100% what I'm talking about lol. Hopefully someone will correct me if I'm wrong.

Regarding the hole to relieve pressure: I believe the pressure inside a sealed enclosure is what makes the woofer response more accurate, which is one of the advantages of a sealed enclosure. That's why I mentioned putting a rubber washer around the mounting bolt and why you need to seal around the wiring cup as well as between the sub and the mounting ring.

As for making it ported, ported enclosures need to be larger and the hole is a very specific size. Ported enclosures with a hole also have a tube inserted in them that is a very specific length. The size of the hole and length of the tube will emphasize a specific frequency depending upon their respective size, so you can't just put in a random hole and expect it to sound good.
...or just cover it in carpeting lol
Bad news is I have 2 massive air leaks between the fleece and the mold itself...
I've always wondered how those two parts seal tightly. I know you wrap it around the molded part and glue it into place. I assume you cover it with several layers of mat/resin. Doesn't that added thickness mess with how the mold fits to the car? Do you only put one or two thin layers on the outside and put several more inside?
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