When guys start to seriously modify their cars for car audio competition, the subject of rebuilding the dash eventually becomes a hot topic of discussion. As many of you know, the factory dashes in most cars are designed for anything but sound quality, so many competitors choose to severely modify or completely rebuild the dash area of their vehicles. Dashboard work can get very complicated, since modern cars have a vast array of critical mechanical and electrical components packed tightly in that area. On top of that, working around shifters, steering wheels, windshields, and door panels further complicates the fabrication process. Since we've been rebuilding a lot of dashboards around here lately, I get a lot of questions from you guys about how to do this properly. Follow along as we build the dash in our center drive Honda Civic demo car.
Once you've removed the stock dashboard, the pivotal first step is to create a framework for your new dash piece. You really have to visualize the dash shape that you want, then create a three dimensional frame that you will later stretch cloth over to form the surface of the dash. For our car, the main feature of the dash was the video monitor array, which stretches across the width of the car and holds five screens. This piece was built with MDF, and then bolted in place on top of our center-mounted steering column. Be sure to make the bolts accessible once the dash is finished, or it will never come out of the car!
Whenever fiberglass is involved in your project, you have to be sure to keep the excess resin from dripping where you don't want it to go. This is especially important for a dash piece, since the resin can easily damage electronics or clog critical steering joints. We draped a layer of painter's drop cloth (plastic sheeting) under the dash area first to avoid these potential problems. You may have noticed by now that we've removed the windshield of our car -- a good move if you plan on spending a lot of time building your dash. The expense is well worth the time saved in the long run, so look into it if you don't have to drive your car every day.
The first step in the framing process is giving the frame something on which to attach. To do this, we taped off the top dash area using masking tape and then followed it up with aluminum foil. Use a light spray glue (3M's Super 77 works great) on the foil side only, then stick the foil to the taped area. Using foil is very important for two reasons. First, it further protects the area about to be fiberglassed, and second, it provides a surface on which to attach the dash frame.
With the foil covering the dash, it's time to start building the frame. Again, remember that the idea here is to make a skeleton out of MDF that will later be covered by cloth. The framing process is the most important part of building any fiberglass piece, since the frame determines the shape of the final part. We used cardboard to make the shape of each rib of the skeleton, copied the shape onto MDF, and then cut each one out with a jigsaw. Using templates like this makes it much easier to get both sides of the dash symmetrical, and it also saves a lot of time.
After each rib is cut, it is attached to the car. Here's where the foil comes in -- we actually attached the rib right to the foil with super glue! It works perfectly. When it's time to remove the dash, the foil separates from the tape, and the piece comes out fairly easily. More ribs are added to the dash structure until the desired shape is achieved. Take your time to be sure the frame looks right, since getting the shape right at this point will save you a bunch of sanding time later on. Notice that it's very easy to see the shape of the dash with the frame complete, even before we stretch cloth over it.
Now that the ribs of the frame are complete, it's time to cover the area with grille cloth. We used regular grille cloth fabric; you can also use regular T-shirt cotton available at the fabric store. Many installers ask why we use such thin material to form our pieces, since many guys use thicker fleece or sweatshirt material. The thick materials will build up quickly, but they also have a tendency to warp easily and crack. Large panels subjected to high temperatures should never be built from thick fleece, since they are most prone to failure. It's always better to keep the forming material thin on large panels, and then build up the thickness with fiberglass matting to create a strong, long-lasting panel.
We used a combination of super glue and staples to attach the cloth to the car. Super glue the edges of the piece first, then pull the cloth and staple it to the MDF ribs. When finished, trim the edges of the dash with a razor blade, and you're ready to start fiberglassing. One coating of fiberglass resin is plenty to soak the cloth, so brush it on and let it dry. Now, you should have a fairly solid surface, and hopefully your dash looks like it did in your head!
Once the first coating of resin is cured, the dash can be reinforced with fiberglass mat and more resin. We used thin, 3/4-ounce mat, and we cut it into small pieces to allow it to lay easily on top of our curved surface. The mat is cut into strips about three inches wide, then torn into squares. The tearing process helps the mat attach much more easily over curved edges and contours. Five or six layers of mat are enough to build approximately 3/16" of thickness, which is plenty of strength for a trim panel. You can apply these layers quickly, and it's not necessary to allow the resin to cure between coats.
With the matting applied, you can move on to your first filler layer. We always start with a layer of Dura-glass, a strong, reinforced body filler, before removing the panel from the car. This keeps the piece from shrinking or warping, since it's held firmly in place by the frame. After the Dura-glass is cured, the dash can be removed and finished. We'll cover that more next month, so check it out. Keep those questions coming to sbrown@alpine-usa.com, and take a look at SteveBrownUniversity.com for some unique opportunities to get hands-on experience using the techniques we've talked about.
01: MDF was used to create the basic frame for the front monitor array, and it was held in place with custom metal brackets attached to the top of the steering column. | 
02: Plastic sheeting was used to cover the car, preventing fiberglass resin from dripping onto it. | 
03: Masking tape was applied over the top of the dash, then aluminum foil was attached with spray glue. This formed a barrier layer over the top of the dash. |
04: MDF strips were cut and attached to the car with superglue to form the shape of the dash. The MDF can be directly glued to the aluminum foil, making the structure of the frame very strong. | 
05: This is the completed frame, showing the shape of the dash in skeleton form. | 
06: Here's another view of the completed frame. Notice the lowered section in the middle of the dash, where a center channel will later be added. |
07: Grille cloth was then stretched over the frame and stapled to it. The edges of the cloth were super glued to the foil covering the car. | 
08: With the grille cloth completely stretched over the frame, the three-dimensional shape of the dash can be seen. | 
09: Fiberglass resin is now brushed on the grille cloth to solidify the shape. |
10: With the resin cured, six layers of fiberglass mat were applied over the top of the grille cloth to strengthen the piece. | 
11: Dura-glass was spread over the dash with it still in the car, which prevents it from warping. It can then be pulled out of the car and finished with a grinder. | 
12: Here's another view of the dash, ready to pull out of the car after being allowed to cure overnight. |