Hi everyone

I just spent a good deal of time putting together a fiberglass enclosure for the passenger side of my G37 Coupe. I thought I'd share my experiences with all of you.

My goal was to add more bass to the existing stock Bose system. The stock stereo sounds good but really lacks that extra kick at times. I wanted to do this with quality components but at a relatively cheap price. I also wanted to retain as much trunk space as possible. I needed the encolusre to be on the passenger side (hence no 4080 enclosure) because I move surfboards around quite a bit. They are much easier to get in the car angled from the drivers side of the trunk to the passenger seat. I also had the requirement of being able to control the level of bass (to a certain extent) from the drivers seat. Different music requires different levels of sub-bass in my opinion. It is nice to be able to adjust while driving.

I'd say overall I probably spent about 6 days on this project with about 5 hours average per day (after work). I know that this sounds overkill but it is worth it to me. I really take pride in doing things myself. There is a sense of satisfaction that you just aren't going to get by going to the store and having them do it for you. Plus, it costs a ton of money to get this kind of work done at a shop. The local shop quoted me about $2000 with all the equipment to do this project. Given the state of the economy that just didn't seem reasonable.

I decided that getting a used speaker makes no sense. They get beat up pretty badly sometimes. I did however buy a used amplifier. My intent was to keep it out of site, so I didn't really care if it had scratches.

Some words of advice: This is not an easy project. It is not terribly difficult either, but it takes extreme patience. You cannot rush fiberglass work. If you lack patience then do not attempt this. You will either have a huge mess or a crappy outcome (or both).

So... where do I start. How about a list of supplies and equipment...

Equipment ~ $315 total

• 1 JL 10W3V3 - $155 new… shipped from eBay.com
• 1 JL e1400d - $100 used on Craigslist.com
• 1 JL RBC-1 Remote Bass Controller - $40 new at local store
• 1 JL 10W3V3 Grill - $20 at local store

Hardware Store Supplies ~ $125 total

• 1 piece of scrap ¾” MDF
• 1 gallon resin
• 1 small can of Bondo
• 1 pack of fiberglass cloth
• 1 pack of fiberglass mat
• 1 medium container of Acetone
• 5 disposable paintbrushes
• 1 bag of 50 disposable gloves
• 1 pack of disposable masks
• 1 pack of sandpaper 80 grit
• 1 large roll 3.5 mil plastic
• 1 large roll of masking tape
• 1 putty knife
• 4 medium disposable mixing cups/containers
• 4 paint stirrers
• 1 roll of tin foil
• 1 wood Glue
• 1 pack of double sided tape squares

Upholstery Store ~ $25 total

• 1 yard of black automotive backless carpeting - $16
• 1 can of spray adhesive - $8

Car Stereo Install Accessories ~ $40 total

• 1 8 Gauge Amp Power Kit - $30 at Fry’s
• 1 Short RCA Cable 4 feet - $10

Total $505


Tools needed:

• Jigsaw
• Power Sander (a palm sander will work)
• Safety Glasses - Important! Use them when cutting and sanding! You do not want fiberglass dust or shards in your eyes! I had a shard hit my glasses hard when cutting with the jigsaw.
• Razor
• Scissors
• Tape Measure

Next up.... pics and step by step instructions

 

Woot woot!!!

 

So first things first... PROTECT THE VEHICLE! You cannot over protect your car. Fiberglass resin is messy and will NOT come out if you spill it on your carpet.

Start by covering everything with the plastic. You need to use reasonably thick plastic, otherwise you risk the resin burning through. Cover everything! You really want to block as much vapor as possible from coming into the passenger cabin. The smell of resin is very strong.




Cover the area you are going to glass in foil. Tape it down well until you can see the form of the enclosure. This will add an extra layer of protection as well.




Make cardboard templates of the base and front of the enclosure. Once they are trimmed to size, trace them onto MDF and cut out the pieces. I chose to make two front pieces so that I could flush mount the woofer.



Some advice when working with resin: Use gloves. I use 2 pairs at once. This will allow you take off one pair and have another clean pair underneath.
Cut out some strips of fiberglass cloth. After mixing the resin, brush a light layer directly onto the foil area. Place the strips of cloth onto the foil. They should stick there. Place the base of the enclosure down and brush additional resin on top of the cloth. This will serve as the initial mold.




Allow this to dry... it will take a couple hours. Clean your hands and arms with Acetone and a rag if you got any resin. Resin particularly sucks on arm hair.

 

great start! ive done 2 of those enclosures at my shop so far, they have all turned out great. youll be very happy when youre finished. great work and keep it up!

 

"Allow this to dry... it will take a couple hours. Clean your hands and arms with Acetone and a rag if you got any resin. Resin particularly sucks on arm hair." FTW!!!!! im hairey as an ape and resin always gets stuck in my arm hair. learned that the hard way and had to shave my arms hahaha! old sweatshirts are my hero

 

Now the mold should be dry. You should be able to pop this out of the car. It will take a little effort because of all the tape.

Here it is...


Add more resin and fiberglass mat until you have built it up to a relatively thick wall. I'd say about 1/4" is about right. This will take several layers and several hours of drying time between. This is the most time intensive process of the project. There is a lot of waiting time. Do not rush this.

So fast forward a day....

Use a jigsaw to cut the mold as square as possible to what will be the front of the enclosure.




Glass on the front baffle. This will take patience and will be messy. Your forearms will get resin on them for sure. After it dries give her a test fit...



If everything looks good and you are going to flush mount the sub then attach the second front. You'll notice that the baffle is not as large as the circle I cut. I did this so that I could make the shape of the enclosure kind of flow once sanded. You'll see what I mean later. Use wood screws and a countersinking bit. You need to countersink the screws so that you can sand the final product.




Here it is out of the car



There is a gap that needs to be covered. I stapled the mat to the baffle in order to glass and close this gap. The baffle was not sitting square against the mold so I used a clamp to keep it in place while the top layer dried.



After letting this dry, apply a few more layers on the inside of the box to strengthen the gapped area. Once you are satisfied with the strength of the enclosure you are ready to sand and add bondo.

 

Add bondo to the enclosure until you have a rough shape that you are looking for. I had to build up the top so that it looked more flush with the trunk wall.




Now it's time to sand and add more bondo. After a couple of layers and more sanding you get the rough enclosure.



From the back...




Now, if you're happy with the box give it a test fit and then cover in carpet. Roll out the carpet onto a large flat area. Use the spray adhesive to cover the carpet back. Spary adhesive on the enclosure baffle as well. Place face down on the carpet. Wrap the carpet around the edges, stretching where necessary. This can be messy and requires patience. Use a razor blade to create seams.




Next let's install the amp...

 

Connect the fused end of the power wire to the battery terminal. Do NOT insert the fuse yet!!!!



Run the power wire through the grommet in the firewall. This is behind the battery close to the top corner of the hood. There are a couple of plastic shrouds that need to be removed to get to this.



The power wire should be reachable from behind the glovebox and will drop down toward the passenger side kickpanel. The kick panel and under-glovebox panel need to be popped off. The carpet has a couple nuts that hold it in place. Remove these first.



Run the power wire down the passenger side and under the rear passenger seats.


After removing all the plastic pieces in the trunk you'll see that on the passenger side there are the brains for the satellite radio and what I think is the voice recognition. I am not sure if the Navi unit sits here as well. I don't have Nav. I wanted to put the amp in this corner so I had to relocate these. You'll see their new location below.




I tapped into the existing factory headunit outputs for the signal and amp turn on signal. I got this form the Bose amp connectors. The Bose amp is on the drivers side in the trunk under the plastic panel. Pin 20 is the turn on wire. Pins 33,34,35,36 are the signal wires. I took a decent RCA cable and cut the ends off. After stripping the wires you can connect these directly to the wires coming from the pins listed above. Here is a thread that explains which wires are which, their color, and location:

https://www.myg37.com/forums/showthr...ght=what+wires

About 7 posts down you'll see a PDF that has the diagram you need to identify the wires.

Once you have the proper wires tapped, run them over to the amp area and hook it up. Insert the fuse now. Fire up the radio and make sure your amp turns on. Hook up your sub and make the amp adjustments you desire.



Put all the plastic panels back on. This takes patience with all the stuff under there now.

 

Hook up the sub and enjoy!







The only thing I have left to do is mount the remote bass boost ****... It sounds great already though!

 

congrats cullan it turned out great! awesome DIY thread too... im sure we will see others duplicating this soon.

 

Excellent write-up!

Don't think I will be doing this (content with my factory speakers) but if I ever decide, this is an excellent guide.

 

Awesome!!!

Thanks for spending all this time

 

wow great job

 

You must have worked in a car audio shop at one time. Reminds me of my good old days back in the installation bay at a shop I used to work at. I did do some installs, but left the fiberglassing to the more experienced installer there. If you have the right tools these project can be so simple and satisfying, I miss having full time access to the large table saw, rolls of carpet, and all the supplies needed.
Great work, and kudos for having the patience not only to do the install, but do a write up on it as well.

 

Yes, actually I did work at a car audio shop when I was younger. Funny thing is that I learned the fiberglass work from DIYs online then too. In fact I never did any glass work at the shop. Just in friends cars.

Fiberglass is a fun thing to try out... just messy.

I installed the remote bass **** this afternoon. I am a happy camper. Time to give the car a wash. I am tired of seeing sawdust on her...