[Robbyho]

Hey, this is Rob from Art of Noise Audio. I build custom fiberglass enclosures for Magnums and other cars. I've seen a lot of interest from people who want to take on the project themselves, so I decided to write a how-to. I usually build my enclosures from molds that I've made of the rear pockets, but I made this one from scratch to show how you could do it. This project is not for the beginner, and if you aren't good with working with your hands, it might be best to get a local shop to do the work. I also offer enclosures for sale and you can email me at [email protected] for more information.

Ok, so here goes. The first thing you need is patience. Anyone can make a work of art, but you can't rush anything. Every step builds off the step before, so take your time and do each step to your best ability.

I used:

2" Blue Painters Tape (not the green, trust me)
Tin Foil
Plastic Drop Cloth
Scissors
Razor Knife
Tape Measurer
Sharpie
Respirator
Dust Mask
Vinyl Gloves
Power Drill
Hot Glue Gun
Air Compressor
Cut-off Wheel
Knurled Bit
D/A sander w/ 40 grit pad
Router w/ circle jig or Jig Saw
40 grit 9"x11" sand paper
2"x4" x11" wood block
2" Disposable Paint Brushes
Bondo Spreaders
Containers

Materials:

1.5 oz. Fiberglass Mat, approx. 38"x 2 yards
Fiberglass Resin, approx. 1 gallon
Body Filler, 1/2 gallon Z-Grip
Tee Shirt Fabric or Fleece
3/4" wood, MDF or a hard plywood
Wooden Dowels

The first thing to do is tape off the Pocket. I use tin foil for the big surfaces, and tape to cover all the seams.

When I taped the pocket, I didn't tape the the front and rear bottom corners and the top corner. Instead I used a piece of tin foil to bridge across them. If I taped tight into the corner, the enclosure would not be able to slide in and out easily when it is finished.

And then cover the floor with a drop plastic.

Now it is time to cut the fiberglass pieces. I cut them to overlap each other and to be bigger than I want the final enclosure to be. It's easier to trim more off than to add more on.

 

[Robbyho]

And I always keep some extra pieces that I can add to the mold after I've laid all that glass.

I get my material from Uscomposites.com. They have great material and great prices. I use 435 standard lay up resin. It is leaps and bounds better than anything from home depot or west marine.

I will spread some resin all over the pocket in order to get the f'glass to stick more easily to it.
I place the pieces on my lay-up board in the same pattern that they go in the pocket. That way I don't get confused as to what goes where.

Then I wet out the pieces one at a time and place them in the pocket. It is important to soak them completely and place them in the pocket before they get soggy and fall apart.

 

[Robbyho]

It's important to get the 'glass to stick when it is hanging upside down.

Notice that there are no air bubbles. I make sure to press them out with the paint brush. It also helps to use fresh, quality resin.

Fast forward an hour or two (in warm weather). The glass has to be hard in order to pull it out, if there are any soft spots, wait longer.
Pulling the enclosure out is a slight challenge b/c all the tape has to be unstuck at once.

I'll pull off as much tape and foil as I can and place the backside of the enclosure in the sun for another hour to make sure it is thoroughly cured.

 

[Robbyho]

And once it is cured, it is time to trim the excess 'glass off. I place it back in the pocket and draw the lines with a sharpie.

And I trim.

Now it is time for more 'glass to reinforce the enclosure. Right now there is one or two layers of 1.5 oz. matt everywhere, which is equivalent to 2-3 layers of 3/4 oz. matt that most shops use. I use 1.5 oz. b/c it makes the process quicker. When using thicker 'glass, it is important to make sure it conforms to all the curves.

When reinfocing, I use strips of 4" mat tape. I overlap each strip and put another 1-3 layers everywhere. The flat surfaces are the weak points, so I place more material there. The enclosure ends up being about 1/4" thick using this process.

 

[Robbyho]

And I let that cure.

I put it back in the pocket and mark with a sharpie where it needs to be trimmed.

Now I make a speaker ring. I like to recess the speaker so it will be flush with front baffle. To do this, I can a) use a jig saw to make two rings and glue them together, or b) use a router with a circle jig to make a recessed circle.

 

[Robbyho]

Now I place the enclosure in the pocket and set the ring up where I want it to be. If I am angling it, I will use wooden dowels to affix it in the right location. Since this sub will be pretty straight, I glue it right to the enclosure. I scuff up the 'glass where it will be glued a bit to get the hot glue to adhere.

I make sure that the sub will have enough clearance to fit. I test fit the sub (or one of equal depth) in the ring to make sure it clears. Then it is time to wrap the box in tee shirt material and soak it with resin. I use super 77 as my spray adhesive.

I use tee shirt material b/c it is thin. Fleece needs a lot of resin to soak all the way through, and to me seems wasteful. I'd rather use that resin on 'glass over the tee shirt material.

I start by spraying both the fabric and the enclosure with the super 77. Then I will wrap the enclosure, starting with the speaker ring. It is important to stretch the fabric tight.

 

[Robbyho]

Then I will soak the material in Resin. I make sure to soak the ring and the edges all the way through, since they have some strength in the final enclosure.

Once it cures I will trim it with a razor knife and d/a and cutting wheel where necessary. You can see the material got slightly warped when it cured, no big deal, I can smooth it with bondo easily.

And here it is trimmed.

Now it is time for some more 'glass. I place an MDF circle over the speaker hole to keep it resin free. I also place 1"x3" strips of f'glass on the inside of the speaker ring to give it strength from behind.

 

[Robbyho]

It cures.

And gets trimmed and test fitted.

I use a knurled bit to trim around the speaker ring.

My favorite part: Bondo. Basically I mix the bondo with some hardener on my bondo board. It is important to keep the bondo board clean. I scrape it clean after every spread and sometimes will give it a quick hit of 40 grit.

 

[Robbyho]

I cut the circle out witha razor knife while the bondo is still rubbery. If you've made it this far without a compressor, you can sand the bondo down by hand. I'll staple a piece of paper to an 11" block of 2"x4" to make a sanding block. That will yield a flat surface.

After sanding the first spread.

And after sanding the second spread.

At this point the enclosure is ready for vinyl. If I were painting it, I would do one more spread of bondo thinned out with resin. If you haven't thinned out your bondo with resin before, try it, it will change your life, I swear.

Now I test fit it in the pocket.

Now off to the upholsterer. I use the OEM light greystone vinyl from Jeep, not from Chrysler. The Chrysler stuff has a cloth back and is awful to stretch, the Jeep stuff is much more workable and looks a lot better. Obviously, my car is slate grey and this enclosure was for someone else.

 

[Robbyho]

But wait, we still need to put in binding posts. Here's the materials I use.

I drill the holes.

 

[Robbyho]

And crimp the ring terminals.

Then run the posts through, tighten them down, slip on the terminals, tighten down the next nut and here we go...

Now some Poly Fil. The rule of thumb is one pound per cubic foot. About 1/2-3/4 bag for this enclosure.

And the finished product.

There ya go, now install the sub, wire it up and you're all done. That wasn't so bad, was it?

Any specific questions, feel free to ask. And If you want me to build you an enclosure, My email is [email protected].

Rob

 

[Robbyho]

Of course, Here is it installed in the car!

 

[aaron1202]

WOW. Good Work!

 

[SoCalRT]

Excellent write up and details. When I built my enclosure it was the first time I had worked with fiberglass. It was a lot of fun and a great learning experience.

Please explain more on the thinning of Bondo with resin. Reason and benefits.
thanks,

 

[Robbyho]

I worked at a classic car restoration shop for 3 years. It was there that I learned the trick of thinning bondo with resin.

Body filler (I use Z-grip) in general is pretty thick, especially in the cold. When it is thick, it is tough to spread and often will get air bubbles trapped inside. When painting something, you want the surface to be as smooth as possible. Once you get the shape that you want with filler, you can put a thin skim coat of bondo/resin that will be smooth and sand easily.

Just scoop your bondo onto your bondo board. Then slide some bondo out of the center and pour in some resin (we call this the mash potatoes and gravy). Mix it up quick until it is marbelized, then add your cream hardener and mix completely as normal.

Adjusting the amount of resin is a bit of a trick to. Sometimes you'll want it real soupy to just give your piece a very thin coat ready for sanding with 80 grit. Or sometimes you are just trying to make the bondo less thick, like in New England winters when outside is 20 degrees and the shop is 50 degrees. Some people even thin it so much that they will paint it on with a brush or through a spray gun.

Hope that helps. Pics would be best, but it is tough to use a camera while your mixing bondo, lol.

Rob

 

[customtronic]

In the car audio industry we call the bondo/resin mix a "milkshake". I agree that it works great. Good article!

 

[IllicitMagnum]

That looks good man, I'll have to do that when I get mine.

 

[smokemagnum]

how much do you sell the enclosures for I would like to buy one for each side of my magnum, I have two 10" JL Audio speakers to put in them, could you give me a call at (270) 307-4731, I would like to do it my self but time is a problem me being a Drill sergeant for the Us Army, so if I could buy them from you would be great so I can start on getting my screens installed

 

[miplank]

yeah....what's something like that cost? also, do you do anything else?

 

[Robbyho]

I sell them for $325 each and $550 for a pair. That includes covering them and shipping to the main 48 states.

I have molds for Chargers as well, but I haven't set a price on them yet. The first two I built had a little trouble with the floor, so I'lll have to shorten them up a bit.

I also make custom Fiberglass enclosures. A lot of people want a 3 sided MDF box with a couple subs angled on the front baffle.

I go nuts with ported and band pass designs as well. I juts built a crazy enclosure that's design I am keeping a secret, but I can tell you that it is full of chambers and vents, and sounds awesome.

Check the site for more info www.ArtofNoiseAudio.com

Rob