HOW TO MAKE RUDIMENTARY MOULDED A-PILLARS

When making rudimentary pillars the first step is to make your mounting plate. Assuming you’re using fairly small midranges and tweeters you’ll make it from 6mm timber. If you’re installing large, heavier drivers into the pillar you’ll make it out of thicker material; common sense is key here. We use timber instead of Perspex or metal for this particular type of design because the resin will soak a lot further into the material. For some of the more complex designs this baffle will need to machined from a more structurally robust and exacting material.

Next you grab a second set of factory pillar trims for a wrecker, as these will become the base for the new ones. You then remove any trim and sand the pillar back with course sand paper like forty or sixty grit. This will rough up the surface which provides a superior mechanical grip for the resin. Moreover, you then drill hundreds of little holes all around the perimeter and across the pillar surface where your trim will meet the pillar. These holes allow the resin to drip through which will provide a very strong mechanical grip. This grip is critical because as the pillars expand and contract in the heat and cool of the day and night respectively; the final layer needs to stay exactly where we want it too.

This step is where you position your baffles and glue them to the pillars. The glue we use is Loctite 401 and we actually use Lego blocks to mount them at the right position. If you’re not sure where the right position is and you don’t want to spend a whole day experimenting with angles, basically if you aim the centre axis at the centre of the opposite head rest you’ll be fairly close to the mark. You’ll be using time alignment to get the stage and image exact in any case. Just a quick note on why we use Lego a fair bit here; Lego is injection moulded to very exacting tolerances, around one hundredth of a millimetre. Therefore it’s terrific for measurements, and because it comes with so many shapes you can set the baffles at any angle you desire. Just take extra time to sit the baffles next to each other to check they’re identical in every measurement, angle and position.

With the baffles in their final position and all glued down you’ll then stretch speaker grille cloth over the entire affair. You’ll recall these are rudimentary pillars holding lightweight speakers, i.e. 3.5″ and smaller; therefore grille cloth is fine for this outer layer. If you’re using larger speakers, i.e. 4″ or larger; this outer layer will need to be stronger glass fibre mat rather than grille cloth. Even with the grille cloth we’re still going to reinforce it with glass mat, but that’ll be on the inside at a later step. Take your time and have a few practice goes dry before you start gluing. The grille cloth should attach to the pillar right where your holes are drilled. If not remove the trim and drill more holes. For without this mechanical grip the pod will start lifting from the polypropylene surface the first time the pillar expands in the sunlight. For nothing sticks to polys.

Quick note before the commencement of this step; always wear a certified respirator, for the fumes and dust are detrimental to your health. Also always wear certified safety glasses, as you only get one set of eyes.

Hopefully by now your pillars are starting to take shape. You now begin the resin process. Grab some polyester resin, MEKP catalyst, 150g chopped strand glass mat and some acetone for cleaning your brushes. Unlike epoxy resin, which must be mixed using a very strict ratio lest it doesn’t cure; you can alter the drying time on polyester resin by adding more or less catalyst. So without going too deep into measurements start with something approximately one cup of resin to one teaspoon of catalyst. This will give you a few minutes of time to paint before it the chemical reaction begins the curing process. Paint it on generously and evenly and just keep applying until you use all the resin in the cup. Then allow it to dry for a few hours. Give any burrs or nicks a gentle sand between each layer and do about five layers of resin. Once dry they should now be solid enough to tap quite hard. For a little reinforcement you then apply your chopped strand glass mat on the inside this time to the rear of the skin, painting them carefully through the speaker holes. This fibreglass within with make the shape near on indestructible.

With your skin now resined it should be hard as plastic, because that’s effectively what it now is. Now you first sand with 80 grit to get the imperfections out. From there you’ll start filling the low bits with filler to get the shape smooth. We use a product called Rage-Gold here, which is like car body filler but a little more flexible. You can also use interior wall plaster too but its not nearly as strong as Rage-Gold. You’ll do this filling and sanding processed continually until the pillars are smooth and have taken their final shape.

The pillars should be almost ready to trim now, so from here we apply a final layer of spray high-fill. This adds about half a millimetre but more importantly it makes it all one colour, which is considerably easier to look at in the light to see if there’re any fine rises or dips that need attention. Even at this stage don’t go too smooth with the sand paper, because the trim will still need that mechanical grip. We usually go down to 200 minimum. If you plan on painting it then you’ll need to go a lot finer with the high-fill and sand process, but for this exercise we’re assuming trimming.

Trim your pillars in material matching your car, whether it be leather, vinyl, suede, Alcantara, minotaur fur; whatever takes your fancy. If you’re not confident with this step simply have your local auto trimmer do it. Upon their return from the trimmer you can gasket, wire and install your speakers. Then pop the pillars back into your car when you’re ready and voila; your aftermarket pillars adventure us complete!