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View Full Version : DIY: Custom fiberglass sub woofer box in a BD



warrior
09-05-2006, 10:39 AM
Fiberglassing is amazing. This is my first time creating something out of fiberglass and it took me about a month because of the learning curve. Don't think you will finish it in one weekend if its your first time.

This box cost me about $100 in material and I will also tell you all the things I learned and the mistakes I made. There are two types of Resin that you can use. Waxed and unwaxed. I used waxed because it's a little easier to work with and has a uniform mixture. The mesh I used was 1 1/2 ounce mesh, I also tried 1 ounce but 1 1/2 ounce is the only mesh that can actually be split into two 0.75 ounce pieces. This is great because two 0.75 ounce layers of fiberglass are stronger than one 1 1/2 ounce layer. Don't buy the 1litre containers, just go for the big 5litre jug because you will use at least 4 litres of it. Mesh is cheap, and depends on you how much you want to build up.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_01-1.jpg
I used duct tape because the resin/fiberglass hardens on the outside, but it will still be liquid where it meets the duct tape on the inside. This will make it easier for you to remove the hardened shell and remove the duct tape. Resin stinks, so do it when you aren't planning to drive for a couple days or not much of a distance. Don't be stingy on the tape, you get resin on your carpet and its ruined. Acetone does remove some of it though.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_02-1.jpg
Outline your shape with a sharpie, it doesn't have to be perfect as you can always sand/dremel the shape. This is just so you don't overdue where you will be laying the mesh down.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_03-1.jpg
Apply a thin layer of just resin in your outlined area. Then, in little cut pieces, lay the mesh on top and then add more resin on top and paint it thoroughly. Don't make it messy but just enough resin so the mesh is liberally soaked.

Let it dry in the sun for a couple of hours before you apply another layer. Add at least two layers so the box will hold its shape. I left it overnight and took it out the next day.

*NOTE* Moisture and humidity are a pain in the ass when it comes to resin drying. I left the box outside thinking it will dry faster by humidity is at its highest at night and with all that humidity, resin doesn't dry at all. It's best to leave it in the garage or even inside your house, though it will stink it up. Resin dries really quickly in the sun!

After you remove the box, remove the tape from the back. It will still be wet so let it soak in the sun until it dries. Do not add layers of mesh/resin to the outside of the box. Always build on the inside. Add a few layers, at least 3 - 4 more so you have a strong sturdy box.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_04-1.jpg
I used MDF board for the front which you can see in the picture, pretty straight foward design. You will need a bi-directional stretch fleece cloth. Meaning, it will stretch from left to right and then also up and down. Some fleece cloths only stretch one way.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_05-1.jpg
You'll need a hot glue gun to secure the fleece onto the fiberglass. Staples don't work well, and you'll have to spend more time trying to flatten them and make them smooth.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_06-1.jpg

https://sl-i.net/FORUM/images/imported/2006/09/subbox_07-1.jpg

https://sl-i.net/FORUM/images/imported/2006/09/subbox_08-1.jpg
Stretch the fleece cloth tightly over the gaps in your box. Once you're secured it with hot glue, you can cut the access away. Now you'll want to apply resin (I haven't mentioned anything about hardener but the mixing proportions should be included in your resin purchase. Use your own discretion) liberally to the entire fleece. It will soak up a lot of resin so make sure you have a lot mixed and ready.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_09-1.jpg

https://sl-i.net/FORUM/images/imported/2006/09/subbox_10-1.jpg

https://sl-i.net/FORUM/images/imported/2006/09/subbox_11-1.jpg

My camera broke and I never got to take pictures of the bondo/sanding process. It's simple really. Once the fiber glass is dry, the box looks like shit. You'll need bondo or sanding putty with hardener and the plastic applicators. Do not use the metal ones, they don't flex and they suck. Apply an even amount of bondo to the front and top of the box, who cares about the back because it will be hidden. In fact, don't touch the back because it will ruin the mold and your box won't fit perfectly.

After you've bondo'd once, let it dry and harden. Sand with 100 grit sand paper by hand and smooth out all corners, sides and top. You may need to bondo a second time with a thin layer to fill in any pits or valleys. Once you're happy with with the texture of the box and the smoothness, prime it. You can use spray paint or brush paint. I used brush paint and applied a think liberal layer.

After the primer dried, i sanded thoroughly with 200 grit, then all the way to 600 to give my box a smooth touch. Paint with your favourite spray paint, I used a wheel coating gun metal.

https://sl-i.net/FORUM/images/imported/2006/09/subbox_12-1.jpg
Voila! Custom box, looks sleek and you have all your trunk space. Oh yea, I ported it as well because a 10" requires a port and is louder. :lol:

blueb3
09-05-2006, 11:11 AM
NOICE! Looks real good.

xcntrk75
09-05-2006, 02:52 PM
Looks great! Hey I used the Charcoal color fabric from Crutchfield and it's a perfect match for the trunk... If you were looking for an exact match... Looks great though!

dropdfocus
09-05-2006, 10:03 PM
Looks awesome!! Great job on the box & nice write up too.

I was going to do the same thing, but I'm going for the stealth look. I'm installing a single 10" Boston Acoustics Pro sub in the spare tire area & the amps in a rack under a raised up false trunk floor.

JjSwee
09-06-2006, 03:49 AM
Real nice!

I am planning on doing this eventually. I made myself a false floor for my amps, and now my sub box sits on it and just ruins the whole theme with the false floor. Can ya tell me how much CF ya got in that box?

Also note to people attempting this: Dont forget about the trunk supports. They slide down and a box not designed for this will be quite a disapointment when you can't close the trunk. :)

warrior
09-06-2006, 08:15 AM
Real nice!

I am planning on doing this eventually. I made myself a false floor for my amps, and now my sub box sits on it and just ruins the whole theme with the false floor. Can ya tell me how much CF ya got in that box?

Also note to people attempting this: Dont forget about the trunk supports. They slide down and a box not designed for this will be quite a disapointment when you can't close the trunk. :)

Yep! That's why my box has that curve for the trunk support.. call me stupid, but what does CF mean.. I tried to figure it out but i have no idea :oops:

Wiscon_Mark
09-06-2006, 08:31 AM
CF=Carbon Fiber

Very Very Nice install! Looks like a professional made it :smile:

warrior
09-06-2006, 08:55 AM
CF=Carbon Fiber

Very Very Nice install! Looks like a professional made it :smile:

Oh yea.. I knew that.. pssh.. but I don't have any CF in there, it's not the CF mesh, it's the fiber glass mesh :cool:

BlueMan0312
09-06-2006, 11:02 AM
maby he ment CF=Custom Fiberglass

JjSwee
09-06-2006, 08:36 PM
Hahaha. I meant cubic feet. How much airspace did you get in that box. I am planning on doing the same for my IDmax and I need about 1.4cf and a 9 inch deep box. (sub is huge - 8.5 inches deep for my 12)

dropdfocus
09-06-2006, 09:24 PM
(sub is huge - 8.5 inches deep for my 12)
What are you installing, a W7 or something jumbo like that??? :shock: Man, 8.5 is pretty deep these days.

JKirk
09-06-2006, 10:19 PM
Whoa, that looks so awesome. :shock:

Plays_with_Toys
09-06-2006, 10:36 PM
GREAT JOB! That looks absolutely awesome, and I'm sure you learned plenty in case you want to do other similar projects.

When you used duck tape I started thinking about american chopper when they tried to make their own seat... :lol:

warrior
09-07-2006, 08:15 AM
Hahaha. I meant cubic feet. How much airspace did you get in that box. I am planning on doing the same for my IDmax and I need about 1.4cf and a 9 inch deep box. (sub is huge - 8.5 inches deep for my 12)

Yikes, that's deep! I honestly have no idea, but I'm guessing its around 1.5 cubic feet.. it's only a Type-R and the only thing Alpine recommended was that I port it if its in a small enclosure and wow what a difference!


GREAT JOB! That looks absolutely awesome, and I'm sure you learned plenty in case you want to do other similar projects.

When you used duck tape I started thinking about american chopper when they tried to make their own seat... :lol:
Thanks! Fiberglass is my new bestfriend, all I can think about is custom this, custom that :lol: Duct tape is the best thing in the world, on the show Red and Green, they made a tire out of shoes for a car only using duct tape and it held together :cool:

Wiscon_Mark
09-07-2006, 09:21 AM
...on the show Red and Green, they made a tire out of shoes for a car only using duct tape and it held together :cool:

I love that show!

dropdfocus
09-07-2006, 01:36 PM
Its actually The Red Green Show. The main character's first name is "Red". Just wanted to clear that up.

dansherman
09-07-2006, 02:05 PM
That's nice looking. I plan on a similar project once I find a good spot in my wagon...

warrior
09-08-2006, 08:21 AM
Its actually The Red Green Show. The main character's first name is "Red". Just wanted to clear that up.

thank you, now I can die happy. :grin:

cyberbackpacker
12-05-2006, 08:47 PM
Just trying to contribute a bit here.

I did a similar project on my BC(?- 92 Legacy).

I built a false floor (in three sections) for my three amps and three processors.

There was drivers side which housed one Boston 8, a PPI frx-456 crossover, and a PPI phase shift controller. The center section went over the spare and housed the three PPI amps (pic shows old zapco before it was replaced with another PPI). Psgr side had another Boston 8 and a PPI DEQ-230. I built the false floor sections first, then built square boxes for my two Boston Pro 8's. Attached the boxes to the false floor. Pulled out the trunk liners and used carboard and masking tape to make contours of trunk. Fiberglassed. Then carpeted.

So essentially I made an entirely new trunk. Only original piece used was the piece right around the trunk latch. I have to say the color match on carpet is pretty darn close.

Pics of process:

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_80_full.jpg
Driver's side section with sub box attached.

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_96_full.jpg
Carboard and tape template

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_90_full.jpg
Fiberglassed

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_17_full.jpg
Before

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_139_full.jpg
After- 1

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_138_full.jpg
After-2

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_137_full.jpg
Driver's After-1

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_108_full.jpg
Driver's After-2

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_136_full.jpg
Spare section After-1

http://memimage.cardomain.net/member_images/2/web/206000-206999/206376_110_full.jpg
Spare section After-2

I was quite pleased considering I had only a jigsaw, a circular saw, and a kitchen counter to cut on. My seams could have been tighter on the false floor, but the fiberglass walls were quite nice IMO.

Hope this can help/inspire someone.

[/img]

blackgtbeauty
12-05-2006, 09:48 PM
the amps don't overheat? or do you not have to cover on all the time?

cyberbackpacker
12-05-2006, 09:58 PM
The amps all are internally cooled (have internal fans), and I also had an additional fan made by Stinger mounted at the far end of the trunk (near the seat back) that pushed an insane amount of cfm's (I cannot recall specifically right now). Never once had an issue with overheating, clipping, etc. Amps had ~1/2" of clearance on top plus 3" to the nearest wall.

2.5GT
12-06-2006, 06:56 PM
I love your set up :eek:

95legacyl
12-07-2006, 09:11 PM
wanna do that on mine? please. thats such a nice system i wish i had the patiance, time, money and what ever other excuse there is to not do it lol, i miss my trunk space but i like the bass :roll:

cyberbackpacker
12-08-2006, 02:24 AM
Thanks for the compliments guys, it is appreciated. If I was closer I would assist, if not entirely do it for you.

It really wasn't "that" expensive. It took about 18 months for it to be completed. But that includes taking my time finding the best deals on equipment, supplies, etc.

Case in point... the carpeting? I paid $30 shipped for an entire ROLL of carpet (4' tall by 2' in diameter)! I was patient assembling it- from planning, purchasing, and then construction.

Also didn't hurt that I was not yet married when I did it. Also my then fiance (now wife) went home to SoCal for ~3 months for summer which gave me more project time! :)

warrior
12-08-2006, 08:33 AM
WOW! And I thought mine was time consuming!

That looks awesome... got any carpet left over? Wanna send some my way? :lol:

blackgtbeauty
12-18-2006, 10:43 PM
I'm gonna have to bump this, I really liek that set up.

subba
02-26-2007, 06:54 PM
i am a man of sound systems but daym u got me beat by a long throw i like it

subba
03-13-2007, 01:11 PM
How much cubic feet of space do you think the trunk....the area where the spare tire is kept?

sheepdog
03-13-2007, 01:42 PM
We used this as a guide to build a box in the back of a friends e36 M3, and it came out great. Great write up.

ryankenn
03-13-2007, 08:06 PM
Spare tire holds about 2.5 cu ft of airspace, more than enough for 2 10" subs. I had a very similar setup in my accord, it basically rocks having a stealth install like this.

http://www.cardomain.com/ride/783341/3

I'm curious with your setup, it looks like you raised the floor level, so the spare is still under there. Does the amp rack tilt up to give access? That would be kick ass to keep the functionality of the spare tire, and have a full stealth install like that.

Good stuff!

subba
03-13-2007, 09:15 PM
umm 2.5 imma try and work something out with it cuz one of my subs only require .5 - .8 cu feet of space

cyberbackpacker
03-30-2007, 07:01 PM
<<I'm curious with your setup, it looks like you raised the floor level, so the spare is still under there. Does the amp rack tilt up to give access? That would be kick ass to keep the functionality of the spare tire, and have a full stealth install like that.>>

Sorry for the slow response. In my install yes I raised the floor level, and the spare (plus the stock storage box that came on the 92) was below it. The center amp rack portion tilted up and allowed access to the spare, jack, etc.

IIRC I raised the floor 3.75 inches. I traced the contours of the floor proper, then used a block of wood that was 2.75" tall (amps are 2.25" plus .5" for air purposes) and used small pieces of paper that I taped down on top of the block to get the proper contours for the top "floor" of the rack. The block was about 4" x 4" so as I completed a small section, I just slid the block around.

This technique insured a very snug, contoured finish without excess slop and movement.

This allowed for me to have the sound I wanted without really sacrificing trunk space. The area where the subs were mounted only protruded ~3 combined from the original trunk paneling.

Dead91silvia
06-06-2014, 12:19 PM
Been trying to figure out how to replace the massive 12" sub and box... Guess I should look in audio more. LOL