I've done this before with minimal success. I used the spare tire well in an 87 Cutlass for two 10" subs. I sealed off the well with 1" mdf and screwed it down with some silione. It sealed quite well, but the bare metal trunk floor made a poor enclosure.
I'm now thinking of doing this again in an 97 BMW convertible. I'll try to describe what is there and what I want to do. The convertibles have an extra brace in the trunk. Picture the back of the back seat; sloped and normally is the front wall of the trunk. In BMW cabrios, the extra bracing is in the form of a vertical steel plate welded in between the wheel wells. It goes top to bottom and side to side about 6 inches behind the seat, but has holes stamped out of it to lighten it. If you took the rear fender off the car, it might look something like this: /|___ With the angled line being the seat back, the vertical line is the brace that I would use as the baffle, and the horizontal lines are the trunk floor.
My thought was to cover that brace with MDF to make a baffle, then try my hardest to seal the whole area between the brace and the seat back and use it as my enclosure. Its wasted space anyway in there. I haven't done the math yet so I'm not sure how big it is, but I'm going to guess between 1.25 and 1.5 cu. ft... which I could fill with something to bring down the volume if necessary.
How about it? Thoughts? Is it going to be way more work than sound quality?
Thanks.
I'm now thinking of doing this again in an 97 BMW convertible. I'll try to describe what is there and what I want to do. The convertibles have an extra brace in the trunk. Picture the back of the back seat; sloped and normally is the front wall of the trunk. In BMW cabrios, the extra bracing is in the form of a vertical steel plate welded in between the wheel wells. It goes top to bottom and side to side about 6 inches behind the seat, but has holes stamped out of it to lighten it. If you took the rear fender off the car, it might look something like this: /|___ With the angled line being the seat back, the vertical line is the brace that I would use as the baffle, and the horizontal lines are the trunk floor.
My thought was to cover that brace with MDF to make a baffle, then try my hardest to seal the whole area between the brace and the seat back and use it as my enclosure. Its wasted space anyway in there. I haven't done the math yet so I'm not sure how big it is, but I'm going to guess between 1.25 and 1.5 cu. ft... which I could fill with something to bring down the volume if necessary.
How about it? Thoughts? Is it going to be way more work than sound quality?
Thanks.
Use fibreglass. Really.
If you cover the area of the car that you intend to use as "enclosure" space with a layer of fibregalss, you can have a removable enclosure which will still use as much as possible of the available space without sinking unnecessary holes in your BMW.
There are plenty of tutorials available on the net, here and elsewhere on making fibreglass subwoofer enclosures, so I won't go into great detail.
It's messy, but not really difficult.
If you cover the area of the car that you intend to use as "enclosure" space with a layer of fibregalss, you can have a removable enclosure which will still use as much as possible of the available space without sinking unnecessary holes in your BMW.
There are plenty of tutorials available on the net, here and elsewhere on making fibreglass subwoofer enclosures, so I won't go into great detail.
It's messy, but not really difficult.
I agree with your assessment, however there are several problems with just fiberglassing.
Take a look at the little picture of my trunk above. The seat back is of course welded side to side, top to bottom. It would comprise the front of the box. The body brace which would comprise the back of the box is about six inches behind that, and also welded top to bottom and side to side. Short of cutting massive sections of the car apart, I can't get in there to fiberglass with the exception of a couple holes that are about 4" triangles stamped out of the steel.
I'll post some photos later if I get the chance.
Take a look at the little picture of my trunk above. The seat back is of course welded side to side, top to bottom. It would comprise the front of the box. The body brace which would comprise the back of the box is about six inches behind that, and also welded top to bottom and side to side. Short of cutting massive sections of the car apart, I can't get in there to fiberglass with the exception of a couple holes that are about 4" triangles stamped out of the steel.
I'll post some photos later if I get the chance.
First line the area to be enclosed with plenty of dynamat or other damping. Make the enclosure from 3/4" plywood, first doing so in cardboard to arrive at the approximate part dimensions. Gaps up to an inch are OK. Fill the gaps with expanding urethane foam, applied in small increments. Allow each foam application to set until hard, about an hour, them trim with a razor and reapply until gradually all the voids are filled and the foam is sculpted to blend the box and sheet metal together. Cover with automotive carpet to color match when everything is fully cured.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.