One of the cleanest S30 I've seen recently.
I'm assuming you bought this in Cali? I may take a trip out there when its time to start another build.
Yup, Cali owned as far as I know. I think I may be the 3rd of 4th owner but not 100% sure, the dry climate here makes a good hunting ground for projects as you said.
This lip/splash guard project took way longer than I thought it would... almost a whole month since I could only find few hours during weekends to move forward. I've changed the design on bracing several times, and finally came up with something that I liked.
I documented pictures of the progress over the weeks, hopefully this could spark some new ideas to you other s30 guys. Most examples of s30/xenon air dam bracing I've found online seemed to only reinforce the top portion to the nose bracket. What I tried to do was find out why/where the flex was happening, and counter it using minimal hardware mess.
The materials I used are: ABS plastic sheet 3/16", 1/8" aluminum panel, 1/4" aluminum rod, rubber stripping, lots of bolts, and two pairs of steel brackets.
At first I thought the sag on the air dam was mainly vertical/gravity induced, due to the flex in the urethane and going through heat cycles from the hot weather. But looking at it closely, evidenced by the stress cracks on the corners, and design of the aero, it actually seems to be more to do with wind resistance pushing down the air dam at a 45 degree angle.
When I held it up vertically it did help with the sag, but not completely until I also pulled it forward to the front of the car at an angle. The top portion where others have fabbed sheet metal or aluminum into - is actually pretty sturdy and has nice thick urethane going all the way across, definitely not the root of the problem.
The thought behind my bracing was to counter where the stress was coming from, to have a forward pushing brace at an angle to offset the wind resistance that's stressing the part.
I outlined the outer edge of the air dam on cardboard, made the template, and cut out roughly similar size plastic. I then positioned it inch higher so it'll give a 1" lip at the arc, and naturally decreasing radius along the edges.
Drilled holes along the little fold of the air dam:
Rubber stripping applied to the outer edge for a smooth look:
Reinforcing the rear of the splash shield to reduce flex, and also to use as a mounting point for bracing:
At this point, I think it was into the second week, and trying to find different ideas on bracing.
My initial thought was just attaching a L shaped bracket where the horns are mounted, straight down. It's simple and would've worked, but it would also look ugly having two brackets coming down that's visible through the opening.
The second idea, was a picture I came across on a BMW forum, where this guy 'sandwiched' two brackets to slip in the rear of the splitter into the slot. I liked the horizontal reinforcement part of it, but couldn't really find a suitable mounting position without making a too big of a L bracket.
So I decided to go with a supporting rod design, which I haven't seen around, and instead of spending a fortune of $80 on APR support rods that are just millimeters, I made my own out of aluminum rods
Cut and drilled, polished little bit to give it some shine:
By having hinges where I can adjust the angle, I was able to preload it a bit and lift/position the splash guard into where I wanted. Results in almost an inch in difference from positioning to test fit. (the brackets along with the stabilizer bolts were eventually spray painted black as seen below)
View from the top, the receiving end of the rod/brace was attached to one of the swaybar bracket bolts.
Crummy over exposed pictures, but this is the end result, very minimal sag, completely rigid when pushed from the front (vs. before with having nothing underneath, it would flex a good inch).
One last engine bay shot before sunset