ClubRoadster.net banner

1 - 12 of 12 Posts

·
Registered
Joined
·
2,096 Posts
Discussion Starter #1
Quick note - this was done in four hours at my parents' house (it's where all the good power tools are. :lol: ) I had to leave early & go back to my apartment in the next city over to go to work later that day. Because of this, and all of the paint prep work I have going on, I wasn't able to make a true splitter with the metal skeleton bolting it to the frame of the car. Regardless, the aero effects are still noticeable to a certain degree. It's been tested up to 80 on the freeway.

So, the other day I made an air splitter, something I've always wanted to have on the car. It's gotten a surprising amount of attention over on the Miata Club FB page, so I decided to do a writeup on how I made it.

Materials:
-4x4 sheet of Polymetal, the same stuff they make "lot for sale" real estate signs out of. I saw this particular sign laying face down in a spot where a bunch of junk was tossed in an empty lot, so in the interest of recycling I used it. Please don't go stealing real estate signs!
-10 or 15 bolts & locknuts of your chosen size.
-3 or 4 feet of steel cable from the hardware store. I used some plastic coated cable from the store at $1.50 for all 4 feet.
-Various cable hardware, all bought at the store. Reference the pictures to see what I used; I don't have the right names on hand. I think they're called cable clamps and cable stops.
-One J-hook.
-Door trim from the auto parts store.
-Self etching primer & black paint.

Method:
First, I made my design by jacking up the polymetal sheet under the car and tracing the lip. Add your desired splitter length here; mine sticks out 3" past the lip. I cut it using tin snips and a hack saw - surprisingly easy.



Then finish the shape with a belt sander.

Next, drill a hole in the hard plastic bumper support. It needs to be one size smaller than the diameter of the eye bolts' threads. From here, you can just tap the hole (lol) by hand and the eye bolt is stuck in there for good.



What both look like…



Now unscrew the eye bolts from out of the bumper support. Here we’re going to be assembling the support cables’ mounting points. This picture shows both of them; the foreground is the cable looped through the eye bolt, which attaches to the hard plastic bumper support. The background is what attaches to the splitter itself.



Basically, you loop the cable through the eye bolt and feed it through an aluminum cable stop. I wanted a cleaner look than what was offered with the two pieces that came in the package, so instead I put the cable stop into a table vice and clamped the hell out of both sides.

Repeat for the other side and screw the eye bolt back into the bumper support.



Now you’re going to want to attach the splitter using your preferred method. Like I said, I really want to go back and build a skeleton for the thing and attach it to the frame of the car once I have time; here is when you can do that if you wish. As for me, right now, I used bolts to attach it to the lip. It was a little tricky fishing around on the top of the splitter trying to use the nuts & bolts, but I’d say it was better than using self-tapping screws (which, in hindsight, perhaps wouldn’t be such a bad idea).

I secured the back of the splitter using a J-hook. I attached the hook to the back of the splitter and hooked it onto the pre-cut hole in the back of the plastic undertray. This also gives it a downward angle up front. I didn’t get any pics because this part was the trickiest.

Finally, measure where you want your cables to be mounted on the splitter. Drill the appropriate holes and loosely bolt in your cable clamps. Feed the cable through the clamp (you can even use a tiny u-bolt here if you want) and tighten it down.
Here’s a good shot of all the hardware mounted up.



Apply some door trim from the parts store, and you’re done!



The cables aren't mounted unevenly, it's just the way the picture makes it look. They line up with the edge of the bumper's mouth.







I left about a centimeter of slack in the cables on purpose to allow low speed obstacles to pass (like the mountainous speed bumps at my apt complex). They tighten up at about 40 mph, according to my video which I made by duct taping my phone to the bumper. ;)

Oh yeah, it's going to be painted black in due time... it just has some self etching primer on there right now. Didn't care to paint it right away as it's going to come off when the car goes into the booth anyways.
 

·
Registered
Joined
·
2,096 Posts
Discussion Starter #3
I originally got the idea from this thread and tweaked it a bit. I didn't like the way the turnbuckles looked, and support rods which you can buy off the web are a bit outrageous at ~$75 a pair.

But regardless, thanks for your input :icon_cheers:
 

·
Registered
Joined
·
2,096 Posts
Discussion Starter #5
Eh I'm not a fan of the way they look. They're too bulky. Plus, if I give the splitter a downward angle starting at the back, then I shouldn't have to worry about providing upward stability; just stability against it being pulled down while driving.

Went for a country road cruise this evening after class. Still holding up fine!
 

·
Registered
Joined
·
2,096 Posts
Discussion Starter #7
Well I finally found the time to go about making a skeletal frame for the thing. It's not as crazy as some I've seen, but I can stand on the splitter and that's good enough for me. It really tightened up the front support cables. I was going to nix the cables and go with turnbuckles, but I need some upward flexibility because of the speed bumps (read: mountains) at my apartment complex.

Made from angled aluminum found at any home improvement shop. Cost me less than ten bucks. I supported the back of the splitter with a jack in order to get the angle right, then measured (eyeballed, mostly) the lengths needed for each section. I was able to cut the angled aluminum with tin snips which made my job way easier, and the holes were drilled on a drill press. Grade 8 bolts were used alongside locknuts and some large washers to increase the surface area against the splitter.

You'll also notice the duct tape on the back of the fog light. The friction fit of the foglight housings inside the NB buckets is a perfect fit, but the tape was an afterthought just to be sure.

These photos, of course, were taken with a potato (approximately 1.3 megaspuds...digital photography has really improved over the years).



 

·
Registered
Joined
·
817 Posts
Building brackets to support the splitter is over thinking it. I prefer to wedge it into the subframe near the steering rack then use cables to support the rest. The nice thing is it can move when you hit bumps rather than shatter. I have tested this up to ~150 mph or whatever a 6 speed and 3.9 maxes out at 7200 rpm and it was fine. Also set up a few other cars this way with success as well.



 

·
Registered
Joined
·
10 Posts
I thought of doing this same thing but instead using some Ebay splitter rods/turnbuckles because the APR ones were way too expensive. Makes for easier installation too.
 

·
Registered
Joined
·
178 Posts
You have too much mods to the front portion that do not go together. There are no smooth transition from home brew Splitter - air dam- NB fog light holes- tsi signal light.
 
1 - 12 of 12 Posts
Top