When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It was a C3, not sure the year. I don't have any pictures of it. He made a plug with expanding foam and fiberglassed over that. It was a real nice write up with good pictures.
He is talking about a sub woofer enclosure but it apparently goes behind the rear wheels.that area is normally called a Gas Tank. Do you possibly mean between the wheel wells?
The setup in that picture are coaxial speakers and not subwoofers. And if they were subs, the enclosure would never be big enough which would result in very poor efficiency.
I'm in the process of building enclosures for 8" subs exactly where you want them, if you want, I can send you pictures as I go along. Mind you, I'm taking my time, so progress is slow. Let me know by PM.
Originally Posted by Richard Daugird
These were tucked into the back corners behind the wheelwell if I remember correctly, and the flat vertical wall in front of the tank was left alone.
The setup in that picture are coaxial speakers and not subwoofers. And if they were subs, the enclosure would never be big enough which would result in very poor efficiency.
Exactly, the picture was just to show where the subs were located. He built the enclosures, they protruded a bit more than those in the picture, and calculated the volume. I think he may have poured a measured amount of water to measure them. I am hoping he will see this and chime in.
And I agree with 7t9l82, post up your project so we all can see!
google c3 sub enclosures it should come up! I saw it too this week. He made a sub enclosure for a 8" sub that fit behind and above the wheel well. A lot of detailed pics.
looked like a good idea to get a pair of subs in a c3
I don't really like being public about what I do to my car for multiple reasons. Foremost reason is I am not a professional in any way and what I do is based on my own understanding of the procedure based on reading the internet and coming up with my own ideas which sometimes work great and sometimes really fail. I would hate for anyone to read what I did and berate me because I'm doing it wrong or that someone else just assumes that since I did it, they should follow suit like it was a tutorial.
Another major reason is that I do this on my spare time... mostly weekends. Having a very demanding job and currently planning a wedding isn't helping in that department. So progress is pretty darn slow, personally I don't mind since its moving forward slowly but surely, but I could see people waiting for a result to be disappointed.
That being said and with all the disclaimers said above, here's what I'm up to. First of all, I went and applied a layer of dynamat xtreme. I was going to layer dynaliner and call it a day but then I read more on all this sound deadening mojo and found out that this combo isn't all that great after all. Essentially, dynamat reduces panel vibrations so covering the whole car is not necessary and most places suggest simply placing pads approx. 2/3 the size of the panel on large surfaces. I don't think what I did is bad in any way but overkill for sure. Here's the dynamat installed:
Now for the dynaliner, it is more of a heat barrier than a sound barrier. A closed cell foam sheet of 1/4" would only absorb sound waves that are very high because the sound wave is so short that it gets stuck in the material. Since most road noises are in the low end, it would require CCF multiple feet thick to absorb it. So what I found is that if you layer mass loaded vinyl on top of the foam, it acts as a blanket that stops all frequencies. It wouldn't work if you layer it on the dynamat directly but on the dynaliner is works as the dynaliner acts as a spring letting the MLV float if you will.
So to bond both together, I first tried 3M 77 spray but found it lacking, especially if I needed to curve the resulting piece. I moved on to contact cement and that worked well. I was worried it would eat into the foam but it didn't. I used the dynaliner adhesive to stick the pieces to the dynamat and then vinyl tape to cover the seams. Here's the result:
I wanted to keep easy access to the body bolts so I made 2 plugs out of XPS foam which I glued onto a pad of MLV. This lets me plug those holes for a flat surface:
All of this was done before moving on to the subwoofer enclosure so that I could get a good feel of the space I had left. My intention here is to glass a wall of sorts that will cover the back and wheel wells. I was never a fan of the open wheel wells in the first place and I think it will look better in the end. So to get that shape defined and to give me an idea of the space I have to work with, I placed strings around the ring of the back bezel and taped them down in the shape I was looking for:
And that's about where I'm at. I started working on the enclosure "plugs" and will post more pictures once I'm done with a side. I use XPS foam and figure out the shape which is constrained but the body and my strings. I glue the 2" boards together with the 3M 77. I'm doing the plug much bigger than it should be so that I can then use a water bath to measure the volume and shave down the plug until I'm about 10% over the desired volume. Once that is done, I'll use epoxy resin (polyester melts XPS foam) to glass the plug, just a few layers to keep the shape. Then I'll dig out the foam from the speaker opening and use acetone to remove what I can't get to. After that, I'll add layers from the inside and ribs on large surfaces to solidify the whole thing.
I intend to mount the enclosures directly to the body by glassing in some mounts. I'll also probably cut the back bezel in half so its easier to install with the added walls I was talking about and bolt those with the original mounts and added mounts at the bottom.
Alright, so last weekend I worked on the foam core on one side, piling up pieces of foam 1.5" thick horizontally. The idea was to really maximize the space used to make sure I wouldn't end up with too small of an enclosure. Once I was done, some quick water basin tests made me realize I it was WAY too big... ended up cutting it in half.
This weekend, I started work on the other side, stacking the foams vertically instead, with the first board flush with the back panel (instead of trying to reach into that far corner where the body mount is). Ended up WAY easier and faster to shape each piece. As a reference, for a 10 L enclosure, I used 10x 1" boards 12" wide by 9" high. I used a home made hot wire cutter to shape the curve going over the wheel and glued together the boards with 3M 77. I liked the result so much I redid the other side in the same fashion.
Once the rough blocks were done, I shaped a clothes hanger to follow my strings at the bottom so I could use it as a guide with the edge of the top trim piece for the final cut. A bit of sanding later I had my blocks where I wanted... they are over sized a bit still as I'm getting 9.5 L and I want to reduce that to 8.25 L since that's what I need if I don't run the ports inside the enclosures.
Next came aligning and positioning the subs in the enclosure. I cut a piece of MDF the size of the sub and glued a piece of a sandpaper to it. I added a handle to help with the grip. The idea here is to "dig" a hole in the foam core, then when the enclosure will be glassed and the foam removed, I will glass in a ring of MDF so I get a nice flat and solid surface to bolt the subwoofer to. Unfortunately, ran out of time sanding in that mounting surface on one side. Here are the images:
This is very similar to the post I saw before, thanks! I like how you sanded away for the recessed hole, I guess you could also mount your sanding disk on a drill motor. Could you explain how you tested for volume, and what did you mean by "10L, 9L, 8.5L"? Cubic liters? Also, I'd be interested in info on your homemade hot wire cutter.
