Anyone who has ever tried to install speakers in the rear of a spider knows there aren't many options. Prior to doing the installs outlined on this page, I had seen two options. One was to mount them to the plastic side panels which cover the rear side windows then the top is down. This option wouldn't provide much by way of bass (or even midrange), plus they might have a tendency to rattle. I've also seen some small, self-contained speakers bolted to a roll bar. I'm not sure how they would sound, but unless you've got a rollbar and can find such speakers you're out of luck. The only other solution seemed to be to cut a hole from the rear seat into the trunk. I didn't want to alter my car that much, nor weaken the unibody. I also wanted to retain the valuable storage space (and occasional passenger space) of the rear seats instead of putting a huge speaker box there. Speaker boxes are also a bit obtrusive and obvious. The soft-top makes it prone to theft too.
A bit of brainstorming led me to remove the rear seat back-support and cut a piece of 5/8" particle board to shape so that it would fit where the back-support had been. I beveled the top edge of the cut-out so that it would fit under the lip that retains the back-support. The measurements were approx. 3'3" wide by 18" tall in the middle and 16" tall on the outer edges. Then I measured approx. 10-1/2" in from each side, and approx. 7" up from the bottom of the board. I figured this would be the location that would give me the most depth behind the speakers, due to the structure of the car, hence giving me the largest resonating chamber, more volume, and more bass. It also left the speakers virtually unobstructed when the top was put down. I then traced the holes for the speakers and cut them out with a saber saw. Originally I installed a pair of Pioneer 6-1/2" 100W speakers, but later cut the holes larger to accommodate a pair of Pioneer 6x9's. Simply place the board where the back-support used to be and wedge the beveled edge under the lip at the top. The bottom part of the seat can then be put in place and will hold the speaker setup snug, just as it held the back-support in place. You now have a speaker setup that sounds much better than the other arrangements and is less permanent and damaging to the car's body and those hard-to-find plastic pieces. NOTE: those with 3-point seat belts may have to cut a small rectangle out of the particle board for the shoulder harness, just as the back-support has a cut-out.
If you don't mind the look of particle board, you're all done. Myself, I wanted a neat, clean looking car, so I decided to carpet the particle board. I bought a 4'x6' roll of Rubber Queen replacement carpeting (which is very thin) from a local auto parts store. Car stereo stores would probably have better carpeting, but this was black (to match the interior) and cheap. I then bought a tube of Liquid Nails for Furniture at my local hardware store. I'm sure any furniture glue would do, so long as it works with fabric and wood. I cut out a piece of the carpeting 3" wider than the cut-out particle board (If you want some really good stuff, try 3M's spray on contact cement). I spread plenty of glue over the entire surface of the board. Don't lay it on too thick though, or it may seep through the carpeting. I then placed the carpet on top, smoothed it out tight and flat, and placed it between two pieces of particle board (plywood would make no difference), and put two spare tires on top of that. This was left to dry overnight. The next day I removed the board and carpeting from its makeshift press. I cut out the carpet where the speaker holes were, inserted the speakers, and screwed & bolted them down. Then I flipped the whole thing over, put glue all around the perimeter, stretched the carpet taught and folded it over the back. I then stapled it to the board so the glue could set. Besides, the staples would give it extra strength. A few skinny triangles of carpet needed to be cut out due to the curve of the wood since I wanted a tight, flush fit. I let this dry overnight and installed it the next day.
Sorry about the poor image quality…it was all I had and I don't have the car anymore.
Here are a couple of pics of the board my friend made for his Spider:
When it came time to equip Eli's Spider with a nice stereo, he consulted me on the install. The whole process, which included shopping for speakers and a head unit, construction of the speaker baffle, interior decoration, and wiring, took us the better part of a Sunday (which really isn't bad!). We also made sure to take some great photos of the process.
There were a few more details to work out with this install than with the one I did in my car. First, Eli decided he wanted to mount the speakers in place of the rear seat, not the backrest. Not much of a problem in itself really. Second, and more importantly, we had to deal with the rollbar. Due to the mounting of the rollbar, we had to design it to slide in and around the rollbar while still covering as much of the rear seat area as possible. This would both improve sound (less air leaks) and improve looks (no gaps showing metal or sound deadening). In order to do this we had to trim little bits off here and there until it would slide in and out relatively easily. Using a piece of cardboard for a template would be advisable to save time, even if you don't have a rollbar. The third consideration was that the transmission tunnel makes the seat mounting area curved, not flat. To deal with this, we made some short, contoured risers to screw to the bottom of our baffle. This also served to level the baffle and provide clearance for the speaker magnets.
As you can see, there really isn't much to it. We took a few simple measurements to figure out speaker placement, cut out the holes, and were done with the hard part. Next we glued the grey speaker box carpeting on (using the super-duper 3M contact cement). We were creative in our use of carpeting to cover up those spots that we had to trim off in order to make the baffle fit around the rollbar. As you can see, it wasn't quite symmetrical, but the carpet masked that nicely.
Next we decided to have a little fun with the interior. The original rear side panels wouldn't fit after the rollbar had been installed. We thought it might look nice if we made some custom panels that fit around the rollbar and matched the speaker baffle, sort of a wrap-around effect or something. A couple ratty old panels from the brown parts car with the Tijuana interior provided our foundation. The old coverings came in handy to draw all over while we figured out just how much would need to be cut out to make them fit.
Then after carpeting...
And the final product...
