At this point in our 2003 Alpine Honda Civic Si buildup, we're pretty much done with the front of the car. The center drive, seat and dash areas are complete and ready for the primer/paint process, so it's time to start on the amplifier area at the rear. We really wanted to do something different with this area, and the center drive gave us a lot of space on each side of the seat to do something cool. We also needed some place to mount our Civic's gauges, since the dash area was completely taken up with monitors. We thought it would be unique to mount the gauges in protruding arms that reach around each side of the seat, connected to the amprack in the back. Here's the problem: how do you get into the car with the arms wrapping around the seat? The answer was to motorize the entire structure back three feet to allow access to the seat.
The first step in building the rack was to make a sturdy base for it. Since the rack had to slide back and forth, we found some industrial-strength forged steel slide racks designed for moving CNC machines back and forth with great precision. These racks are amazing, since each bearing cap can handle 10,000 pounds of load capacity! That means that with the four caps we used, we could support 40,000 pounds of weight. Obviously, the strength of the car's unibody is the limiting factor here. With the sliders bolted into the car, we built a steel frame on top of them that the fiberglass rack layers would bolt to. Then, we added the final touch, a 12-volt linear actuator with 750 pounds of load capacity to allow the rack to move back and forth. Now the mechanical structure for the rack was complete, so it was time to build the rest of it.
Our concept for the rack was to have three layers, each one holding an amplifier in the back and Auto Meter gauges in the front. Each layer was built separately by creating an MDF frame along with ABS plastic attached by super glue. These layers were bolted together by installing aluminum plates between each one. The frames allow the amplifiers to be mounted in the back of the rack, and gauges to fit into the front.
Once the layers were framed, they were removed from the car so they could be fiberglassed. Grille cloth was stretched over each one, then the cloth was coated with fiberglass resin. After that was cured, each rack was reinforced with five layers of 3/4-ounce fiberglass mat, making them very strong. Since they are fairly long and thin, strength was very important to make sure they didn't flex or rattle when installed in the car. Dura-glass filled the initial imperfections in the panels, then that was ground down and followed by a thin layer of Rage Gold filler to smooth the surface out.
There were many small details to take care of with these pieces as well. We molded the actual heatsink fins of each amp precisely to match our panels, creating a very clean, flush look. The fitting of each layer to the other also took some time, as did the building of the ABS plastic-bottom panel to hide the steel structure below. With all of these steps completed, the racks were bolted back into the car to check the fitment of every detail. When everything checked out, the racks were ready for the primer/paint process.
01: An MDF frame was built as a jig for the motorized rack sliding mechanism. One-inch-square tube stock was then clamped to the jig and welded together. | 
02: Here's me holding the 24-inch stroke, 750-pound linear actuator used to move the amp rack. | 
03: Machined bearing sliders were used to slide the rack, and the assembly can be seen here installed in the car. Notice the 1-inch tube stock welded to the top of the amp box to support the sliding rails. |
04: The basic shape of each arm was formed by attaching five pieces of MDF together with super glue. | 
05: The frame for the second rack was formed again using MDF strips. The amps can be seen here being test-fitted in their future homes. | 
06: The front of the top layer holds the largest gauge on each side as well. The framework for all three arms can be clearly seen here, in the forward position. |
07: Notice that the grille cloth was stapled to each edge of the MDF sides, thereby maintaining the shape of the panels. | 
08: Dura-glass was used as the first fill layer over the fiberglass. | 
09: The body filler was sanded down to smooth out the shape of each panel. Notice how the heat sinks of each amp are fitted to the panel perfectly. |
10: With the amp rack all the way back, we were able to check clearance between the amprack and the rear hatch area. | | |
That's it for this month, but check out SteveBrownUniversity.com for some unique hands-on opportunities with these procedures, and e-mail questions to sbrown@alpine-usa.com.