When I was looking for a bit of aerodynamic assistance for my 2006 MX-5, there were a couple of different ways to go. One was to go with a wing. The other was to go with a rear spoiler. ST5/TT5 rules allow for either.
Wings offer the downforce you want, with less drag than a spoiler, but they are more expensive, and since I didn’t want to have to go with the additional expense of a front splitter, I went with the spoiler and a simple Ebay air dam up front. Front splitters get torn up when you go off track — and then your car doesn’t handle right — and since I still have a tendency to do that, I didn’t want to have to be fixing broken splitters once or twice a year.
For the NC chassis Mazda MX-5, I purchased a rear spoiler kit from Blackbird Fabworx, which makes Lexan rear spoiler kits for all generations of Miatas and even Fiat 124s and Honda S2000 cars, too. Blackbird also makes a line of roll bars for those cars, too.
The nice thing about the kit is that it comes with everything you need. Mounting hardware is all stainless and the nuts are all Nylocks, so you don’t have to worry about rust or having nuts back off the bolts.
It also comes with good instructions, but not illustrated to the extent we have here for you in your favorite racing publication, NASA Speed News. As good as the instructions and the kit are, this is one of those jobs where it helps to have an extra set of hands for some steps of the installation. Also, be patient and take your time. The old saying, “The work determines the pace,” definitely applies here. Go slow and steady so you can go fast later.
There are some must have tools for this installation, chief among them an automatic center punch. By simply pressing down on the punch, it self-cocks and delivers a blow that creates the dimple you need to keep your drill bit from walking. I didn’t have one for years. Now I wonder how I ever got by without it.
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This installation calls for lots of holes, so fresh drill bits are a big plus, and blue painter’s tape to protect the paint while you are drilling and installing and removing the spoiler. A pencil for making lines and marking spots is better than a Sharpie in this case, because you might need to erase a mistake or two.
The installation also calls for a straight edge to keep the spoiler straight and vertical before marking the final mounting holes. In our case, we used a small length of aluminum L angle stock. Flat stock won’t do because it bends. The straight edge is critical to getting the last holes in the right place. You also will need some pinch clamps to hold the L angle to the surface of the spoiler.
After I had it installed, I could feel its effect, most acutely in higher speed turns where the car used to get a bit loose, like Turn 9 at Willow Springs for example.
We took a few hundred photos of the installation, but what follows are what we thought would be most helpful. Here’s how the installation shakes out.
A nice big workbench is a good place to lay everything out and preassemble what you can. Before doing anything on the car, you can attached the two outer bolts of the piano-style hinges on the triangular mounting tab and the actual spoiler itself. Leave the innermost bolt out till later. Also, leave the protective film on to keep from scratching the Lexan.We covered the working area of the deck lid with blue painter’s tape. You have put the spoiler on and take it off repeatedly throughout the process, so it helps prevent scratching the paint any more than you can tolerate on your track car.The instructions say drill a quarter-inch hole 7/16 of an inch from the front point of the decklid, 13 3/4 inches from the front corner of the decklid. Then drill a 13/64 inch hole 3/8 inches from the edge and 17 1/4 inches from the front point of the decklid. The precision with which you locate and drill these holes paves the way to a successful installation.The holes drill right through the decklid’s outer lip, outside of the weatherstrip on the body underneath. Do both sides. Now, get the partially assembled rear spoiler to continue the job.Here’s how the sides mount up. The front bolt is going to bend the triangular Lexan mounting tab a bit, so just start it on the threads. There are two spacer brackets in the kit, which mount as shown. They are different left to right. Snug down both sides. Remember, at this point, we are not installing it, but rather mounting it so we can locate and drill the rest of the mounting holes on top of the decklid.With your straight edge fastened to the surface of the spoiler, hold the spoiler vertical and mark the remaining two holes in the triangular mounting tab.When you drill the holes, be sure to drill through deeply enough to penetrate the outer and inner skin of the decklid.Using a step drill, enlarge the holes you drilled in the inner skin of the decklid. This larger hole in the inner skin allows you to put a nut in a shallow socket and spin it onto the bolt that goes through the spoiler and decklid.When all the holes are drilled, peel off the tape. This photo shows all four mounting holes on the decklid for the triangular mounting tabs.Now you are all set to start all the bolts and nuts on the triangular mounting tabs.Before you tighten all the bolts, slide the weatherstrip onto the center section. You’ll have to peel back the protective film.Now you can drill the three holes on the rear vertical section of the decklid. Locate the center one first, then drill the right and left holes 14 1/8 inches outboard of the center hole. We tried saving the Mazda emblem, but we broke it. Oops.Now you can attach the three support struts for the spoilerI opted to remove the protective film before I snugged and tightened all the bolts. That way I could get all the film off from around the bolts.With all the bolts started and the protective film removed, you can snug and tighten all the bolts. Rember the forward-most bolt on the point of the triangular mounting tab bends the Lexan. It just needs to be snug and have the bolt biting the nylon ring in the Nylock nuts. Note: It is not necessary to remove the taillamps for spoiler installation.
