Thread: Need Suggestions: 03 Vibe GT Subs...

I'd hate to search police you, but if you search this forum you can find many ideas, rather than let this post be just that, here's some helpful info:

It depends on how you want the finished product to look.

If you want a square (rectangle) box (easiest) just use MDF (at least 1/2" but 3/4" is more recommended.) You can pick up 4' x 8' sheets for about 20-25 bucks at home depot/lowes. Just make sure that you build it to the right interior volume (don't forget to subtract the volume of the sub itself.) it's on your sub's info sheet, or rockford's website, or as a rule of thumb per sub: (for sealed chamber boxes):
8" - .66 - .9 cuft,
10" - .75 - 1 cuft,
12" - .9 - 1.25 cuft,
15" - 1.1 - 1.5 cuft.
(Note that the larger the box, the "boomier" it will sound, the smaller the box, the "punchier" it will sound.)
The best is to use a separate chamber design so that the subs aren't "fighting" for air-space or against each other. (This applies with the following designs as well.)

A flat box, but with angled edges (to match angle of seat back):
Use the same method as above, but cut the edges to angles.

A combo of flat and round pieces:
Use MDF for the flat parts, since Fiberglass isn't strong unless it's curved. And make a sort of skeleton for the fiberglass parts (mdf is again easy). Lay fleece over and stretch and staple. Apply resin. Repeat a few times until the thickness is about 1/2" or about 5-7 layers of glass (on top of the fleece) are down. Sand. Sand. Sand. Sand. Filler. More sanding! If you are carpeting, you would need it to be fairly smooth, if you are painting it, then it needs to be PERFECTLY smooth, otherwise imperfections will show once the paint is done. (This forum has a LOT of threads about how to build FG boxes, also Alpine uses alot of FG in their demo cars, spend a few minutes there to get an idea of what they've done.)

Odd-shaped, custom molded, or wheel well designs:
If you are looking to install these behind the wheel wells, you will use a minimal amount of MDF, and maximum amount of FG. Lay down a release agent (most people will put down blue masking tape covered with aluminum foil on the carpet to keep the shape, and provide an easy release. some even spray cooking oil (pam) on this to aid in release when everything is cured.) then apply the first layer of glass directly on the carpet/foil. apply at least two more layers before removing from the car to add more layers (to about 5-7 total as above). Then follow the above steps, but add the glass to the inside of the box, to keep the back shape. For the other "half" of the enclosure, make a sub ring (usually out of MDF) and "hover" it where you want the sub to be in the end (and anything else, amps, etc.) Use hot glue and dowels or more MDF to get it to stay (make sure it's secure) and lay more fleece over this connecting it to the back half. Lay down more glass, and begin the finishing process (sand, sand, filler, sand, filler, etc.) Make sure that the boxes are symmetrical in volume for the subs to sound right. (within 5% volume difference.)

keep in mind that non square shapes are hard to calculate volume. The easy way is to get a cardboard box that has the right volume, and fill it with packaging peanuts, then pour them into the completed box, as long as it's pretty close, you should be just fine.

Also, make sure to seal ALL edges, for MDF, usually foam insulation or silicone sealer (in the squeeze tubes) is best. For fiberglass, a layer of glass and resin on the inside edge works really well, but is sometimes hard to access.

In any case, keep in mind that you will need to run your speaker wire to the sub, and it would be important to seal this hole as well.

In the end, the best for your set up would be behind the wheel wells. It will allow you to fold down your seats, and still fit big things in the back.



I would use the edge of the load floor as the maximum distance the sub box should extend into the trunk. (where the gloves and rope lie) I'd also try to follow the curvature of the wheel wells, so that it looks like it's supposed to be there. Mask the floor past this line, glass up to and slightly past this line, you can always remove material later. Then when the back piece was done, I'd make a template of the wheel well curve, and cut out mdf to make "ribs" to attach the fleece to and glue them to the back half. On the right side, there is an indentation, I would put the amp on this side, and fill the space so that it is the same volume as the other side.

Most people would flame you for not running a quick but you got lucky this time.

Have fun with your project!

Thanks for the post, I did search, I just didnt know what I was searching for. You gave me some great Ideas, and I think Im gong to do to the taping and fiberglassing idea. Im not sure how you would do it, with how you were suggesting it, but I think that Im going to tape all of the left and right side, to the crack, where the spare tire lid is, and fill all that space with the Subs sitting in the back corner facing the driver/passenger. The amp is already next to the spare tire, tucked away and I put carpet down overtop of all the hard plastic. (My dogs kept slipping on the hard plastic, but they dont with the carpet.)

So, something like this is what I was planning. So, my question, with the information you gave, is:
I would tape off past the line, put down the fiberglass, let it cure/dry put down another coat, cure/dry. Remove it, keep putting on coats. Put it back in the car, place the sub where I want, connect the back piece and the floating sub with mat, glass the mat till its solid. Remove the dowels and whatnot, sand paint and Im done. Considering also the amount of space. Sounds easy...Im sure its not though.
But, anyway, does all that sound about right? Now what did you mean about the 'ribs'? I think that my next weekend is going to be shot. Thanks again. Ill take pictures so if I mess up, everyone can laugh, or if I do good...you can still laugh.

The one you circle is where I have mine. well only on the passenger side.
My Fiberglass Sub box

It's my first timer to fiberglass so it isn't look good but it serve it purpose.

MatrixPC's set up shows what I mean:



See how the masking tape goes past the line? you want to cover as much as possible to make sure that fiberglass and dripping resin only fall on surfaces you want.
- Go crazy with the tape; put it way past what you plan to glass.
- Next I'd put a layer of tin foil on top of the tape layer. this helps get everything out when it's hardened.
- After two or three layers of fiberglass (that have been layed larger than the final dimensions) it can be removed from the car for further layers.
When laying the glass, you will get some smell in the car, it will last a few days, but should go away pretty quick. A fan and really good ventilation help with this.
- Once the back piece is done and hard, place it back in the car for test fitting. Mark where you want the edge to be, and cut with a rotozip, sawzall, whatever...
- Then, I'd personally make two ribs that are the same curvature of the wheel wells. Here's kind of what I mean:

Watch this slide show of how the Alpine install team uses fiberglass to make their own body panels, and sub enclosures.
http://www.alpine-usa.com/US-en/fun/...&mode=&play=30
They use ribs on the seat enclosure, and throughout the car.
here's two screen shots:

Notice the top pic shows the ribs, and the bottom shows after the fleece has been stretched. you ribs will be closer to the shape of the wheel wells.

- first make a template of the existing curves with cardboard, something fairly close is ok, you will get your final shape when you cut the mdf.
- cut out MDF from the template, then place the ribs on the back piece so that the front of the rib lines up with the front of the back piece, and the top of the rib meets the side wall of the back piece. This will form the structure of the front piece, and keep the shape that you want. I'd also place the sub ring between these two ribs either connecting it directly to the ribs, or using dowels and glue.
- alternately, you can just hover the sub with dowels.
- Stretch and staple the fleece over the sub ring and ribs to the back piece (secure the fleece to the back with more glue.) before the next step, now would be a good time to check volume and make adjustments to the front design before having to make a second one later.
- apply resin to the shape when you are satisfied with it, and of course more layers of fiberglass. no need to resin the inside of the sub, you will cut it out after it's all hardened.
- After 5-7 layers, you have something close to your final stage.
- Optional - layer one or two layers of glass along the inside joint to add strength and structure and seal the enclosure. Otherwise silicone sealer works well here. The box needs to be airtight.
- Sand everything down so that it's pretty smooth. Apply body filler to fill in the low spots. And sand it after it's dry.
- The sub ring needs to have a perfectly flat surface for the best seal. to do this, a power sander is a really good tool, sand it down to the mdf.
- If you are using carpet for this enclosure, now would be a good time to carpet it. (once there are no major dips or bumps)
- If painting, the surface needs to be immaculate. keep sanding and filling, sanding and filling until it's perfectly smooth (run your hand over the surface, you will be able to feel any scratches, small bumps or dips) then prime and paint it.

Somehow you'll need to get wires into the box. drill a hole just barely large enough to fit your wires, and then seal with the silicone sealer to make sure everything is airtight.

Alright, I went ahead and did it. So here we go.....

I carpeted the back of my Vibe, and its a mess from the MDF I cut, so bear in mind, I need to vacuum.

Next pic is Taped.

Then Alllluminuminum foil.

First / Second Coat

3rd and 4th Coat...and then it rained. Thats it so far...

Comments?

good job so far, I started to do my new box:
http://www.mp3car.com/vbulletin/fabr...lkthrough.html
This may also help you with doing yours.

You are using fiberglass mat right? It just doesn't look like it in the pics.
Keep up the good work!

I didnt use Fiberglass mat in those pictures. I just got the basic shape down, and now, I cut the hole for the sub using MDF and 'floated' it. Then put down the mat. I dont have a staple gun, so tape was my friend. And, I used alot. Considering the odd shape I want (I want to be able to get to my spare tire, so I want a bit of curvature PLUS straight lines) I had to tape up alot of places where the mat just wrinkeled or had soft spots. I JUST finished doing that and its 10:30pm, and raining. So tommorow I will apply more fiberglass untill this thing is solid. I made a mistake and didnt check for volume, so Im PRAYING that theres plenty of space. I know, dumb, but its my first box and I got really excited. After I put down the first layer, Ill check for volume, if its short, then Ill cut and modify using mat, I bought plenty. Ill also post pics tommorow. I know 1 thing for sure, its time consuming if you dont have a jigsaw or another MDF cutting tool. I keep telling myself " And I have another one to do!?!? " I hope its all worth it! Thanks again for the advice, I guess this should be moved to worklogs, could someone do that?

Alright, here is so far.....

First post, shows where the box is, and the opening. also the shape.

And second post shows all the tape I had to use to keep that damn shape as I didnt brace the box and it moved, so I had to brace it and then fiberglass it with the braces in to get it back to form...I think I cracked it somewhere.

Well, this IS my first time. learning a buttload here!

Oh and that little Leatherman in the first pic is a bloody godsend! Thank you leatherman!

Well, I scrapped the whole first one. Its gone. I took the small lessons I learned from that mistake and reapplied my efforts on this on...So, here we go.

First Had to tape and then place the ring of hope. Took a second to get it right...



Then onto the Matt...

Final shape, just needs more fiberglass. Then...LOTS of friggin sanding. So...yeah, Im much more happy with this one.

I know if I asked for comment, Id get a million critiques...so..COMMENTS!?!? i NEED ALL THE HELP I CAN GET.
[edit]....sorry, forgot caps was on....[/edit]

[advanced edit]Oh, and Ive gone through 4 rolls of painters tape...I need a staple gun...[advanced edit]