Welcome to project Stealth Box.

JL audio makes some of the best vehicle specific sub woofer enclosures on the planet. Their boxes are not mass produced. Each box is a one off made by hand from custom molds.

I found a box made for the VW Golf that would be perfect in my car.

 

This box is a perfect fit for the VW. Too bad it won't fit my Lancer. So what can I do? I can make my own box.

I have a little bit of experience with fiberglass. I have made several boxes, amp racks and kick panels. I decided to put this build here on Sound Domain so other can learn with me.

I started off with a gallon of Polyester resin and three packages of fiberglass cloth. The cloth I bought at Wal Mart and the resin came from US composites and West Marine.

Supplies needed:
Latex Gloves
Brushes
Mixing bowls
Acetone for cleaning
MEK
Cooking Oil (Pam)
Painters tape
Aluminum foil

I started off with a nice clean spare tire. This tire has never seen the ground.

 

 

Then I started to tape off the tire to create a barrier between the tire and mold area.

After the tape was applies I used spray glue and foil to make another layer of protection for the tire.

 

Once the tire was foiled I added more tape to protect the sides of the tire. The last thing you want is resin on any surface other than the mold area.

A table would be the best choice for a work area. I used an old Best Buy sign I had in my garage. If you use a table cover it in wax paper. This will protect the table because the resin will not soak through the wax paper.

 

 

Add in the MEK per the instructions. Too little MEK will cause a slow curing time. Too much MEK will cause the resin to heat up and dry too fast. The mold can crack and warp.

Mix the resin throughly. It will change color when it's properly mixed.

Spray the surface with the cooking spray. A mold release will work as well. If a release is not used it will be impossible to remove the mold from the tire.

 

 

Paint the resin on the mold area and then lay the fiberglass cloth.

 

48oz of resin was used with two packages of mat.

 

I then cut a piece of 3/4 mdf the size of the inner tire. This will be where the mounting bolt is added to hold the tire down.

The disc and mold had resin applied to glue the two together.

Then mat was applied over the mdf ring. When the resin dries it will make the MDF and fiberglass
mat into one very solid surface.

 

The mold needs to dry for 24 hours to set 100%. If you remove it too soon the mold may warp.

If you use more cooking spray then I did you won't have as much foil left in the mold.

The next step in the box building process is the wood frame.

I used a cardboard box to made a template. It's easier to use cardboard then wood. If you cut too much you can alway tape some back on. try doing that with wood.

 

 

From there I cut a piece of 5/8 MDF for the bottom of the box.

 

 

I did the same process for the top of the box.

 

 

The 5/8 MDF was again used for the top.

 

 

I used two 1/4 x 3" wood to raise the top and bottom pieces of wood.

 

 

After 24 hours the mold was removed.

 

 

I placed the mold on top of the wood box for test fitting.

 

 

The tire was laid in place for fitting.

 

 

The mold needed to be trimmed to lower the height of the tire.

I used a jigsaw to trim down the edges. Be careful cutting fiberglass. It's sharp and the dust can get glass fibers in your skin. If you get it in your skin take a cold shower to close your pores. Hot water will open the pores and cause the glass fibers to go deeper in your skin.

The next step is to cut the frame down to make room for woofer and raise it away from the floor.

Bottom

 

Top

 

The first thing to do is join the fiberglass mold to the wood. People will argue all day on the best way to do this. More resin, bondo, liquid nail or some other glue. I chose an adhesive that bonds to plastic, wood, ceramic and general construction materials.

I first applied a generous layer of adhesive around the opening of the wood frame.

The inside lip of the mold was filled with more adhesive.

 

 

A heavy container was placed on top of the mold to press it in place as the adhesive dried.

 

 

The inside panel that was removed earlier was cut for the 10 inch sub woofer. A 3/4 MDF ring was also cut and glues to the back side of the 5/8 MDF. This will make the speaker mounting surface stronger. Two pieces of 3/4 wood were used as mounting brackets to reattach the panel to the wood frame.

Remember when mixing MEK and resin that you take into consideration the temperature outside. Curing times will be accelerated in the heat and slowed in the cold.

The next step is joining the mold and wood with fiberglass and resin.

The adhesive bond is very strong but I want more fiberglass and resin to help if form a stronger bond.

 

I used up the rest of the cloth mat to start the foundation. Then I switched to chop mat. I prefer cloth because it's not as messy.

 

With the thicker chop mat I bought at Home Depot I used the soak method. The mat was cut into small squares and dipped into the resin mix. From there it's laid on the mold and pressed down with a paint brush.

 

I used T shirt material to fill in the gap between the bottom of the box and the speaker mounting insert.

This old Best Buy shirt worked perfectly. I used a stapler to attach the material and the stretched it into place. The material was again stapled on the other side to hold it in place.

The T shirt material was painted with a thick layer of resin.

 

The panel was flipped over and the pack side was also painted with resin.

 

Fiberglass mat was added to the back side of the t shirt material for extra support.

Time to put the box back together and attach the material to resin. Normally you would use fleece or cotton. I choose carpet because of the thickness. Getting resin on the inside will be a challenge.

I used a staple gun to attach the carpet to the box frame.

After the carpet was applied I used a razor blade to remove all the excess carpet.

 

Time for more resin. This carpet takes A LOT of resin.

My 9 year old son doesn't have the camera skills down 100% but you can see what I am doing.

 

Bottom and sides have the first coat.

 

Flipped the box over and coated the top and sides.

In order to resin the inside of the box I had to mix a hot batch of resin. I poured 24oz of rein into the box and then rotated it so all inner edges would be coated with resin. This took about 10 minutes of rotation. To avoid doing this yourself, cut the wood frame a little smaller and use a thinner material. That way you can build up to the size needed.

For the next step I have to build up the box and fix some imperfections caused by the carper not being as tight as it could be. For this I used Bondo's version of rage gold. I hate regular Bondo body filler. It's too think and not very forgiving.

 

 

After 25 minutes I can go back and sand it down before adding a few more coats.

Second Coat

Resin time

After it dries I will do some fine tuning on the sanding. Since it will be carpeted and not painted the finish does not have to be perfect.

The final shots are with carpet. It kicked my butt. With all the curves I am thinking paint or trunk liner next time.

Finished product

 

 

All that is left is placing it in the car.

 

I wasn't too happy with the carpet job so I decided to use bed liner. First coat here.

 

 

Page 1 Introduction and pictures
Page 2 System
Page 3 Sound Deadening
Page 4 Old system
Page 5 Box Build up

Page 6 Power Wire

Page 7 Accident