Speedflaps are a simple device placed forward of the front wheels to help direct air around the tires thereby creating less lift, more downforce, better steering response at high speed, and less of the infamous MR2 shimmy. In Japan, Speedflaps came as standard items on the later MKIIs.

What you’ll need:

1/16” x 2’x 2’ 6061 Aluminum Sheet (about $20)
8-10 1/4” bolts, washers, and nuts
Loctite
Drill with 1/4” bit
Jigsaw with aluminum cutting blade
Bench Vise
Paper
Marker
Tape
Fine grit sand paper
Flat Black Spray Paint

The first thing you’ll need to do is jack your car up, put it on jack stands, and remove the wheel. After this is done get a piece of paper and marker. Use the paper to make a template for your speedflap. You’ll do this by laying the paper against the front inner fenderwell of your MR2 and trace the shape you’ll need for your speedflap. I decided to make mine a large “L” shape so it would fit around the fenderwell vents I had cut. The “L” shape also gives more rigidity and strength to the speedflap. My particular template came out with the following measurements: 2.5” x 7” x 9.75” x 3”. You can see a picture of the template below which should give you a better understanding of the measurements and shape. After making your template you will need to tape it flat against your Aluminum sheet. Next, set the AL sheet on a large, flat bench and find someway to secure or weigh it to the bench. You can use C-clamps or any heavy object. Once the AL sheet is secure you will need to begin cutting out the template shape with a jigsaw. Make sure you have an AL cutting blade otherwise you’ll be very unhappy. Remember to take your time and not to rush the blade through the AL. The next step once you have the AL cut to shape is to place it against your MR2’s inner fenderwell making sure it is going to fit how you want it to. In my case, I needed to cut a slit at the very back of the lower lip to slide the speedflap into and thus allowing it to rest flush against the fenderwell. Once you have the speedflap’s positioning figured out decide how many and where to drill holes for the bolts. Upon deciding your bolt hole numbers and locations mark them on your speedflap. Then put the speedflap in a vise or drill press and drill the holes. After drilling the holes make sure they are large enough for your bolts to slide through and that they are in the right places. The next thing to do is to take the drilled speedflap back to your inner fenderwell and place it against the inner fenderwell to mark the location of your holes onto the fenderwell. I just simply held the speedflap in place and drilled through the bolt holes and into the fenderwell. The plastic is easy enough to drill through that doing this is quite easy. Once the holes are drilled, you’ll need to test fit everything. Get your bolt, washers and nuts and secure the speedflap in place. If everything fits you are ready to begin painting. However, before you begin painting you should use the completed speedflap as a template for the other side. Your previous template will have been cut up in the jigsaw. Painting is pretty simple, all you need to do is scuff the AL with a very fine grit sandpaper. After scuffing it wash the AL thoroughly to make sure it is perfectly clean. If you don’t get it perfectly clean you’ll end up with bubbly paint. Once the AL is clean all you have to do is spray a few coats of flat black paint onto the speedflap and let it dry. After the paint is dry all you have to do is install the speedflaps making sure to use some Loctite on the bolts.

Testing The Speedflaps:

Upon completion of my speedflaps I went out to test them. To do this I simply got on the expressway at a time when traffic was light and drove the car at various speeds.

Here is what I found;

At speeds above 65-70mph the speedflaps improve steering response and seem to add more downforce. How can I tell? Well, this is kind of subjective but I could feel that the front end was not as light as it had previously been, especially at speeds over 100mph. Also, steering response seemed to be increased because, well, the steering response was quicker. The steering was not “light”. However, this increased downforce and steering response can be a bad thing as well as a good thing. Due to my aggressive alignment settings the increased downforce seemed to aggravate my car’s tendency to track the road and thus necessitating more attention to high speed driving. If your car does not have an aggressive alignment you should not experience any increase in road tracking. Another thing I noticed is what I thought was shimmy from air flow is actually shimmy from variations in the road surface. Again, you ask how do I know this? Well, as I was driving the shimmy would come and go with changes in the road surface. Sometimes at 120mph the car would be perfectly smooth and there would be no shimmy but at other times the tires would shimmy. All of this was in relation to the road and I made sure of this by going over the same bits of road at various speeds. So, there you have it. Speedflaps are easy to make and install and well worth the minimal effort involved. Given the fact the later JDM MKII MR2s came with speedflaps from the factory it seems like it is a good idea to install them.

-- John Pruner
redvalkyrie


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