Subwoofer Box Fiberglassing 2

From Nissan 350Z & 370Z Wiki

Fiberglassing tutorials duplicated courtesy of Chris S. His website is here: Chris's Fiberglassing Tutorials

Please Read First: Any practices carried out by using the information provided within these web pages should be done with extreme care. Fiberglass resin fumes are harmful, MDF particle dust is harmful and working with power tools can be potentially dangerous. Always use extreme caution and the proper safety equipement, (i.e., respirator, safety goggles...)

This is the area of the car that was chosen to work with. The original box is a huge bandpass box and takes up nearly the entire trunk and sounds bad. The goal here was better sounding bass, and a useable trunk. Before we can do any work, clear the area as best as possible. Remove all debris, vacuum is necessary. Smooth out the carpetting as much as possible. You can remove the carpetting if you wish, but it may make the enclosure harder to remove later on. Tape off the entire area with masking tape. Try to estimate how large the box will be, and go about 3-5" beyond that, this will be excess glass that you cut off. The tape is layed right over the carpet, and since it will be removed later, it will be easier to pull off---if it was taped to the metal body, it would be very hard to remove (sometimes you may need to use a release agent on the masking tape if you are glassing and will not be able to remove the tape easily.) This is cheap masking tape, which works fine, but if you spend a few bucks more you can get the blue painters tape, which sticks well, and releases easier.

For extra safety, I sometimes put aluminum over the tape as well. The purpose of the tape is so that resin does not seep onto the carpet of your car. I put aluminum foil over the tape, just incase the tape has a rip that I cannot see. In all actuality, if you are careful, you do not need to use aluminum foil. This is a shot of the trunk after aluminum foil is put in place. You'll notice quite a large section is taped off -- the box is not intended to be this large, but you want to cover more area just incase there are any accidents -- if you get resin on your carpet, there is little change it will come out without a problem. This is the proper type of mask you should wear when doing this kind of work. Since you are in a confined area, it is important that you use an actual respirator and not a particle mask. With this on, should be not smell a thing -- no vapors at all. It is worth the buy and comes in handy. The full mask shown here is $25 at home depot, however if you dont think you will be fiberglassing alot, you can buy disposable respirators for $9.

This is after 1 layer of glass has been put down. The procedure for applying glass is the same as described in the first tutorial -- resin surface, lay matt, stab matt, remove air bubbles, repeat. Also, remember when mixing up the resin and hardener, do not mix a whole lot at once. This process takes some time and the resin will gel up if you take too long. The bottle will give a recommended amount of hardener to use-- this is usually estimated at ~70degrees, so if it is colder, add more hardener, if it is hotter you can add less. If you add too much hardener, your work time will only be a few minutes before it gels up---to little and itll take a day to dry. Even though the bottles of resin comes with a hardener tube, ive always found it not to be enough---so just buy an extra tube. You can speed up the process a little sometimes by putting heating lamps over the structure while it is drying. After about 2 hours, the glass should be dry to the touch and you can remove it from the car. It will flex a little upon coming out, this is ok, it will retain its shape. Work your hands around the carpet and pull the entire thing out. Then remove the tape and foil as best as possible. The rest of the work will be done outside the car.

This is how the fiberglass will look with the tape and foil removed -- it is very thin at this point and pretty much transparent. You can now add additional layers of fiberglass. Remember, no more than 2 or 3 layers in one sitting, and dont apply again until it is dry to the touch (a little tacky is OK). After your layers have dried, test fit the enclosure. You can see in this picture quite a few air bubbles that I did not remove -- you want to get rid of those, it will weaken the structure, here, I tested it and it was strong enough even with the bubbles, so I did not trash the project. Use a marker and outline the edge of where you want the box to end.

Use a rotozip / dremel or saw to cut off the edges as per your markings. Wear long sleeve t-shirts, and particle mask and safety goggles. Next, you want to mount the MDF rings. You can see how to make these here. The wooden rods used here are 1/4" wooden dowels from Home Depot and are $.40 a peice (4' long).Cut them and place the ring as you want it positioned. I used hot glue to secure the rings and dowels. Once it is all dry, make sure it is strong and wont move or get pulled out of shape by the fabric drying. This shows the second ring mounted. Again, make sure the rings wont move or fall apart.

Cut the cloth you are going to use to a workable size. Wrap the enclosure, keeping the front wrinkle/kink free. You can use hotglue or a staple gun to attach the fabric to behind. After pulling the cloth around and attaching it, cut away all the excess. This will make it easier to finish later on, and easier to work with.

Dip your brush and paint on some resin. Cover the whole area, except for where the speakers will go, leave that just fabric bc it will all be cut later.. The dark rings you see in the pic is the MDF showing through--make sure you resin that part so that the cloth sticks to the wood. If you want to use the same brush between coats, you can soak the brush in acetone while the glass is drying, this will save the brush from haredening up. Once the fabric has dried, you can begin applying fiberglass to it. Keep adding layers until it is strong enough -- 7-9 layers is usually good enough. This is the box all glassed up -- waiting to dry. The can in this picture is a gallon size of resin, and if you plan on doing a decent amout of glassing (this project applies), buy it in this size. 1 quart of resin at home depot/lowes/walmart is $10, but if you go to a local marina, or boat shop you can get 1 gallon of resin with hardener for $16 -- its the same stuff just alot cheaper. Look in the phone book for marine supply, or go to westmarine.com and look for a nearby store.

Once the entire structure is dry, cut away all excess glass. Cut close, right down to the wood. A Rotozip/Dremel works great here. Test fit speakers. Once the entire structure is dry, cut away all excess glass. Cut close, right down to the wood. A Rotozip/Dremel works great here. Test fit speakers. Wire up the subwoofers and drill a hole in the back for the wires to go through. Seal the hole with a bead of silicone. You can use terminal cups, but i often find them to leak, so i simply drill holes. The box shown here was never finsihed, and was left as is. You may finish as you see fit (paint, vinyl, carpet)