I wanted to try some aerodynamic improvement on my wagon, and was looking at CF splitters like the APR for (yikes !) $300-$350. Not going to happen...One of the NASA instructors ran in the Speed World Challenge TC, and I noticed the splitter on his SRT-4 was plywood. That gave me the nads to fab one myself.
The first thing I did was select a material, something stiff, lightweight and easy to work with. I opted for a coated white panel board for about $20.00 a 4X8' sheet. I am not sure this is the right choice, but will wait to see how it holds up under track use and weather. I chose the 1/8" thick stuff which is pretty thin, thinking that with many mounting points it will have the needed rigidity.
Next was making a template, which I did with a large sheet of cardboard, and a lot of head scratching. Getting the overall shape wasn't that difficult, but getting the mounting holes in the right place was tedious. I also had to accomodate a way to access the oil filter.
I took my panel board and template to a furniture maker friend of mine who has a good jigsaw and the skills to make nice smooth rounded cuts. We cut two, since a parking bump or off track excursion will trash the thing, and for $20.00 it's nice to have spare. Pictured are a piece of the template (I did one side only, then gate-folded it) and the panel cut, with no mounting holes.
Like I mentioned, finding the right spots for mounting holes was difficult. I drilled them all 1/2" since my mounting plan was to use 1/2" pop rivets, similar to the ones that hold the now useless mud guard on. The semicircle cut-out is for oil filter access.
I purchased a pair of APR support rods ($55.00) which are a really slick piece of engineering. they are definitely needed to support the middle of the splitter. I wanted my home fabbed job to look like the $350 one so I covered the top with some vinyl sticker sheet ($26.00) made to look vaguely similar to carbon fiber. I used some 3" wide aluminum tape to protect the board where it is close to the heatshields around the exhaust manifolds. Everything fit well and mounting it was a snap. I incorporated the two bolts that hold up the mud shield, and the 8 holes (4 per side) in the bottom of the bumper for the nylon pop rivets ($8.00) I used washers for the 2 bolts and support rods ($2.00)
My impressions after installing it on a rainy day, are that it may be vulnerable to moisture. The vinyl will help, but only time will tell on that. Since I made this for a combination of a little downforce and to smooth out under car turbulance, my concern is that while it may have been at an appropriate angle when I had Tein springs on the car, it is too level now to create any downforce. I do not want to use an aftermarket lip to get it lower in front, since I am constantly taking stock of how many modifications points I have tallied up to run my car with NASA. I think I will have to use one of the ghetto-fabulous hardware store door molding lips to change the attack angle. I can tell it is almost dead level by the way the rain puddled on it as I finished the job, so at this point it is a good belly tray and a nice appearance mod. That will have to change before my first track event. My only other concern is that it will accumulate mud in front of the tires, I may end up changing the shape slightly if that is a problem. Depending on how this holds up, I may re-do it with a 3/16" panel and weather coat the crap out of it before I mount it. I needed to do one other thing to the front of the car to be safety ready for the track. Notice that I couldn't leave the tow eye plain !! From working on the front bumper all day, it was apparent that after all the thrashing I've put the car through in the mud, dirt and snow, it might be time to get the bumper cover repainted !!