Want to see this project step by step? Check out the Fiberglass Box How-To Page

I got the old sub box pulled out of the car. After that it's just laying down the glass to make enough of a model to pull it out of the car and finish. I've decided against doing MDF top. The divider and halos will be MDF though the top fiberglass also.
Here's what's left of the box.

I found a picture of a JL Audio 4th gen Trans Am and they gave me the idea for my box. My new box takes up the complete hatch area including some that were under the panels. Here's the pic of the inspiration.

Here's pics of my bracketing I made out of cardboard.

Here's the start of the new one.

Just got the new subwoofer box popped out of the car (which I used as a big mold to get the fiberglass shell). Here it is!

So just how big is the this new box compared to the old one. This next pic shows that. Please note my new box wasn't sitting all the way upright either and it's still wider than the old one.

Here's what the driver side looks like without the box installed. This shows others where I had to cut the panel for more space.

I used 0.75 OZ fiberglass on most of it using a B-440 Construction Resin which I bought from USComposites.com Then for a few places I used 40.5 OZ Aircraft Quality fiberglass on it for added strength overall there is around 7-8 layers.

I filled the box with water to find out the overall cubic feet. I was going to use packing peanuts but by my guess I would need a crap load of them. ;-) I put the box around 35 gallons of water just by guessing I was way off. It ended up holding near 53 gallons of water. I had to use a floor jack and boards to prop the car up cause the rear suspension was sagging so much. So when I used the formula: 53 gallons / 7.481 = 7.08 cubic feet

Also that means the box was holding over 440 lbs of water without leaking!
NOTE: Edges have been cut off giving a nice straight lip.

The divider is now in the box it's seated with liquid nails and the material is 3/4" MDF.

I have the MDF subwoofer rings also built. They are also 3/4" MDF which is doubled to get a seal on the bottom and to recess the woofer after I fiberglass them in place. They are held together with liquid nails and 4 1 1/4" wood screws.

I had to use the belt sander to get the rings to fit in the box due to clearance reasons shown in the above pic.

I have them mock mounted just waiting till I get some time to cut some MDF supports out and get it all slapped together.

Here's one with the new MDF supports and the wooden dowels so it clears the hatch shocks.

NEWS!!! I just got a new shipment in via UPS! No you're not seeing double there are 4 18s there. I found yet another killer deal on ebay. 2 BRAND NEW Kicker CVR 18 4 Ohms and a KX1200.1 amp all new in the box for $666 shipped. I gotta figure out what to do with the amp since I prefer JBL 1200.1s, but I figure there going for 380 now on ebay so I can sell on there or my friend really likes kicker stuff so I might sell to him for 300 bucks. Either way I scored 2 more brand new 18" CVRs for 140 to 180 a piece shipped excellent deal.

***Sold the amp on ebay for 340 bucks after fees and sold the subs to local guy for 400 cash***

Fleece went on today and was covered with resin 6/30/04

I cut the subwoofer holes out and test mounted the box in the car 7/5/04.

Overall I'm very pleased by the way it's looking.

Ok I finally got around to redoing the wiring job the local audio store did for me. Get this they ran 4 feet of 4 AWG to the caps from the optima... then 8 AWG from the first cap to the second cap. There was no outlet so the discharge had to go all the way through the 4 feet into the battery than out of the battery 4 feet back up to where the caps were to hit the amps on separate lines. So by the way I read the instructions it clearly states within 18"s of the amps else you can lose your power over the line... so I redid it all feeding the caps with 4 AWG each and then going off the caps to the amps using 4 AWG again. I had to turn one cap around so don't freak out when you see 2 wires going from 2 different caps to the same amp. It had to be done that way to keep it 18" or less wiring.

I did new wires from the optima also since they put all 3 4 AWG in a 0 AWG connectior *roll*. So I ordered more connectors and got that all fixed up.

I also went back and used more 0 AWG for the wiring under the hood. They went 4 feet from battery to fuse with 2 AWG then 2 feet from fuse to isolator with 4 AWG then it was my wiring I had done before with 0 awg. Go figure no wonder I had power issues. I went ahead and put a 0 AWG ground and alternator wire on also. I also tested after that and only showed 12.7 volts at idle (due to under driven pulleys), so I swapped back to OEM alternator pulley now I get 13.7 or 13.8 volts at idle and full 14.0 or 14.1 at 1k rpms!

Also I have 4 layers of fiberglass on the lid part of the box now. I found one of my supports broke loose from the box. Probably due to heat and stress from resin curing on the fleece. So I got that liquid nailed back down. Here are the pics!

OK guys I went back and put a full layer of biaxial 32 oz on top of the mat. I went ahead and did 3 layers of biaxial on the wide areas on the outside corners of the lid near the hatch shocks. It's rock hard now. I went back and put 2 layers of biaxial on the front lip and 1 layer on the sides.

Also you're probably wondering just what exactly is biaxial cloth? Well it's a form of hybrid. The top side is a 45 degree woven material and the bottom side is regular heavy duty mat. It's done this way because you're not suppose to have woven touch other layers of woven. This saves time, effort, and resin packaging it all together so you can just put down 1 layer instead of a woven and mat each.

Here's what it looks like once it's dried. This is on the wide part that's why there is 2 different directions of lines since I did multiple layers.

Threw a quick sand job on it to take care of all the coarse stuff. (No need to cut myself open yet again this project.) Test fitted the box!

I've went back and laid 2 more layers of biaxial inside the box by the gas tank slope (weak point). I'm not done with laying the fiberglass I believe. I started the bondo stage on the lid. I have about 2 hours of sanding (useing electric block type) so far and not making much progress.

I have around 7 hours bondo and sanding in now. Here's the pics!

Ok, should be ready for spot putty. I don't have any right now so I worked today on the cardboard ideas for the rear seat 18s, here they are!

I went back and added a bondo milkshake to the box. This consisted of 2:1 ratio of bondo body filler and fiberglass resin. It helped add stiffness to the box and filled in all the little leaks. There's almost 2 gallons of bondo on the inside of the box now. I had one small spot that was weak on the rear wall with about 50 to 100 lbs of force it would flex so I put a good 1/4" layer of milkshake there.

I also tapped all the subwoofer screw holes with tee nuts and used cap screws. The inside also has 2 tubes of silicone on the divider wall from both sides.

Here's the finished pics!!! Woofers are wired for a 2 ohm final each (1300 watts+ from the JBL 1200.1 to each).

The box has finally been drilled for the mounting grilles (10/9) I don't really like the way the mounting ears are sitting but I didn't have much choice. I can always smooth it out later with some more bondo work. I'll get up some pics eventually. I need to silicone all the drill holes first and let it cure before I put the subs back in.

Silicone has been cured for over 2 weeks now (11/25). I'm just to lazy to put the driverside sub back in. I'll get to it sooner or later.

Here's the box with the grilles installed.

Want to see this project step by step? Check out the Fiberglass Box How-To Page

Site Index:
Page 1 - Introduction
Page 2 - Current Project To Do Lists
Page 3 - The Interior
Page 4 - 2 18" Kicker particle board box (old design)
5 - 2 18" Kicker fiberglass box custom <-- You're here
Page 6 - General Mods
Page 7 - My Z20 Special Appearance Package
Page 8 - My fiberglass non AC heater box mold (1LE version that has been discontinued by GM)
Page 9 - New High-PO 383 in the build
Page 10 - Glasstek Hood Repair
Page 11 - Fiberglass Box How-To
Page 12 - My Xbox Game for 1� I bought from the store with proof
Page 13 - SOLD! Twin 62mm T4 Turbo Kit From BBS DESIGNS for 1200 HP! SOLD!
Page 14 - To Do List before motor completion