Okay, it's all done. I made the aforementioned pieces for my Element.
Start with a giant piece of coroplast, and cut away everything that doesn't look like a belly pan. :-) The belly pan reaches fron the rocker panel on the driver's side, to the edge of the heat shields for the exhaust, which goes down the passenger's side of the car. I also made a smaller pan to cover the space between the passenger's side rocker panel and the edge of the exhaust system. Attachment points consisted of (from front to rear) anti-sway bar, pre-tapped sidestep holes, the bar that protects the gas tank, and the rear suspension subframe thing. This was all made easier by the fact that my E is a 2wd instead of a 4wd. AN IMPORTANT TIP: Get TWO giant pieces of coroplast. One to make the pan, and one to provide a nice smooth surface to roll around on, cuz you gonna be rolling around under there for HOURS.
Like most cars, the rear underside was shaped like a parachute. Pretty easy to cut a piece of coroplast to the right size, and then hold it in place with zipties around the antisway bar in the front, and tuck it between the rear bumper trim and the body in the back, held in place with the OEM trim clips.
The insides of my rear fenders had a huge empty space, so I made it smaller. The liners follow the top of the wheel arch and are held by the OEM clips and screws that hold the exterior plastic panel to the metal subframe. There is not much suspension travel back there (verified by driving only one rear tire up onto a rhino ramp), so I think I'll be okay.
No rigorous testing has been done. The pieces do not tear themselves loose at 65 mpg, so that's one important hurdle out of the way... :-) Pics in the next post.
Thanks guys. MnFocus, the rear seriously took less than an hour.
Mentalic, at one point the Coroplast belly pan did pop out and touch the muffler, and it melted a lot. I have added some more ties and I think I'm in the clear now. On the rear, I made a little shield out of a coke can that I think will protect that part. Thanks for bringing it up though. Coroplast IS flammable...
Looks great! I was looking under my Subaru and have absolutely no idea where to mount a tray. The front has nice holes, but how did you mount it under the car other than the front/back edges?
Thanks. I did some different stuff for attachment points.
The front attaches to the antisway bar with zipties.
In the middle, I found some threaded holes that I was not using, and bought bolts to bolt the belly pan to those. There were also a few places where I made hangers out of a wire coathanger. Basically found a couple of holes next to each other, threaded the wire through, cut to length and bent it all how I liked, and then ziptied to that. This was necessary around and behind the fuel tank, since I didn't really want to tie anything to the fuel tank itself.
So it sounds like nothing is too permanent. That makes it sound easier than I was originally thinking. I looked under my car and tried to think where I could attach a big flat piece and had little luck. Are there any other sections where you worried about heat and melting the plastic? I have no mechanical knowledge, so I didn't know if there were any spots that I should avoid covering. I guess I just need to raise the car up on something and take a better look.