This Tricks of the Trade is about the sub/amp install in a Honda Element. This vehicle served as one of Alpine's show vehicles a while back. Some of you may recall that we ran another how-to on the building of the pillar-mounted speaker enclosures in the magazine. Here we focus on the subwoofer/amplifier area in the rear hatch. This is a good example of a nice-looking, easy-to-build custom project that won't break the bank. If you haven't worked with fiberglass very much, a simple project like this is a good way to get some experience.
1) Our Honda Element project vehicle received a complete Alpine audio/video system. In the hatch, we wanted to have good bass in a nice looking package, so we decided to put the amps and sub in the spare tire well. The first step was to make a ¾” MDF border around the edge of the spare tire area.
2) Making the enclosure for the 12” subwoofer was simple, since we decided to make it out of ¾” MDF. Notice how the top of the box angles the woofer up slightly, for better viewing of the Alpine equipment. This box was bolted through the floor of the spare tire well to keep it in place.
3) We also wanted two amplifiers to mount behind the subwoofer enclosure, so we welded ¾” square steel tubing together to form mounting frames for each amp. If you don’t have a welder, a local welding shop can perform basic welding like this for a nominal fee.
4) Next, we placed the steel amp frames where we wanted them, and temporarily held them in place using MDF strips and super glue. More ¾” square steel tubing was welded between the amp frames and the spare tire well to permanently mount the amp frames. Now, we have a complete amp rack that is welded into the car.
5) All of the components are in place, so next up is the framing process that dictates the shape of the top trim panel. The amps are mounted on the amp rack, and an MDF rectangle was made to fit around each amp. An MDF ring fits around the subwoofer as well. MDF strips are then super glued between these components and the MDF border that we made in step 1.
6) The front view shows how each amp is framed, and how the ribs connect these frames with the border around the edge.
7) Polyester grill cloth is now tightly stretched and stapled over the frame, followed by five layers of fiberglass mat to build strength. Once this has cured, a layer of Dura-Glas goes over the top to fill any major surface imperfections.
8) After the whole thing has cured for at least 12 hours, it can be removed from the car. A grinder is used to roughly finish the surface, then a layer of Rage Gold body filler finishes off the filling process.
9) The Rage Gold is sanded down with 36 grit sandpaper to make the shape smooth. At this point, the piece should fit well, but if any additional filling is needed now is the time. We decided to fasten the trim panel to the car by using three bolts on each edge.
10) To hide the six trim panel bolts, an insert was made on each side of the trim panel. Masking tape covers the area where the insert is needed, followed by a layer of aluminum foil.
11) More fiberglass mat is added over the insert area, and the piece is finished in the same fashion as the trim panel with Dura-Glas and Rage Gold.
12) One additional detail we added on this installation was a skeleton housing to hold two 6.5” video monitors. This was done with MDF, with a little Dura-Glas and Rage Gold on the edges to smooth out the look.
13) The final product shows a nicely integrated and custom subwoofer/amp/video display. We decided to paint the main panel silver, with black accent coloring on the video mount and on the bolt-concealing inserts on each side. As an added bonus, the subwoofer rocks since it loads well against the rear hatch door.
