The Mazda factory rear air dam for the Miata is a bit of a rare part. It was discontinued around 2002. I was fortunate enough to acquire one a few years back. A factory one, not a copy. I remember the day well. I held it in my hands. I admired it. And then I cut it in half so it would fit my trailer hitch.
Well, you live and learn. I think I would have opted for a hidden hitch that didn’t require me to hack up my rare and beautiful rear airdam now days. But I wasn’t always so careful with my Miata modding.
And then this happened in late 2008, as many of you have seen.
As you can see, the air dam lived though the wreck just fine. It got a bit scraped, but it was ready for more. I unbolted it after I bought the car back and it sat on a shelf for a year.
Poor unloved air dam. All cut up and scratched up. If only there wasn’t that gaping hole in the middle.
One day I realized that I could easily fix the air dam by casting a new piece to fit in the empty slot. Pretty easy when you have a whole room devoted to the casting and painting of tiny robots.
I used Dow Corning HSIII silicon to make the mold with. Maybe overkill (you can do hundreds of pours with very little mold degradation), but I love the stuff. So easy to work with.
The original pulled out of the silicon very easily. I had to cut the cup off, but I just put the mold into a new cup to minimize overflow. In the background is the Alumilite casting resin that I like to use for this stuff. I used the white since that’s what I had available. Great stuff. Very strong. About a 90 second cure time.
Megatron helped me out a bit.
“Kick” is the technical term for the plastic turning from a liquid into a rubber. It creates a lot of heat in this step. Very cool. I’ve poured hundreds of castings and this still impresses me.
It’s a little more work than you see here, but not much. I decided to pour two plugs in case I went a little too crazy with the dremel on the first one. Why dremel? I measured how much of a plug I needed and then poured an extra half inch to give myself some room to work.
Many thanks to Megatron for the help.
I managed to not get any shots of the bondo work. I’m disappointed in myself. I thought I had dozens. They seem to have gone to that great digital photo grave yard in the sky.
3 coats of primer. 3 coats of montego blue. 4 coats of clear. And not very much wet sanding at all! I got lucky and didn’t have much in the way of orange peel.
So. How does it look installed?
I love how it looks. I’ve always loved how it looks. And I’m very pleased with my little repair here. You can only see a hint of a seem from a couple inches away. Hopefully, my bondo and plastic welder (glue) will hold up to vibrations and scrapes for a few years.
And one more time, because I think it’s pretty.