Paint and Body DIY undertray thread

Maier Racing body panels, widebody, etc. Good reference for hood and splitter. What I mentioned about the hood is obvious from their panel, a huge cutout from about where the pulleys sit to the back of the radiator, as well as a cowl on the back, and cutouts to the left and right of the engine as well.

I was unable to find much else on that forum explicitly for Foxbodies, but a lot for SN95 mustangs here and there. I'll have to dig around a bit more but it's great info that can be universally applied, so thanks for the suggestion there.


Seeing these posts makes me want to go "full racecar" so bad. But I've tried to stick with just restomod/ grand touring style. I need to buy another fox just to use as a test bed! Maybe when I'm done with college... Time and money is in short supply lately.

Asked around my university, but no luck for the wind tunnel - we have one, but sadly it's not large enough for a car, only a few feet wide. I could make a scale model but that's just as involved so, I think my best bet for any engineering analysis is to get an .STL file and use SOLIDWORKS flow simulation for computational fluid dynamics (CFD) which I do have access to through my university, and I know my way around enough to use

Now I would have to either get a decent STL file scan of a foxbody (Underside included) which doesn't seem to exist, or create my own.
Files are out there for the body of the car, but no underside, as these files are typically made at 1:25 scale and used for RC cars and 3D printing


This is about the best thing I could find, but for making an under tray or anything like that it would be a bit inaccurate since the bottom of the car and drivetrain isn't modeled.
If anyone DOES happen to have a 3D scan of a foxbody, I'm all ears

Haven't gotten a chance to go out and get any measurements or scans, life's been smacking me around a bit lately. But, I did find a really good series of videos made by an Aussie fellow, He clearly has a lot of knowledge on aerodynamic and automotive design. He has many videos on custom fab for a front tray, body tray, diffuser, and even proper venting for his intercooler and the rear of the car to reduce high pressure areas behind the bumper and rear end while still keeping car parts cool. Very informative if you prefer videos to old forum posts.

So, been a while since I updated this thread but rest assured I'm still thinking, researching, and working on things... College and work is a *****! That and I'm building an engine and doing a 5 lug swap, but here we are now.

I bought the part file for $3 on that website and scaled it to the proper dimensions, and I'm looking into design for the undertray. Hopefully I can get this to a point where I can do a Solidworks flow simulation and use that to find design issues as well as points of interest and pressure on the body of the car. It won't be perfectly accurate by any means but rough is good enough for this application, and it does seem to be a pretty good model.

My main constraints that I'm focused on beyond just making a flat floor are:
-Splitter and diffuser design
-Brake cooling/ducting (Likely 2 small inlets on the bottom of the splitter to guide air up into the brakes like the performance packs on newer mustangs)
-Transmission cooling via a NACA duct
-Differential cooling and preventing rear end / suspension interference while still having a "mostly flat" floor
-Hardware and mounting bracketry
-Ducting or cutouts at the rear of the bumper to allow any high pressure air that makes it's way above the undertray to escape and not just create lift
Ideally this would be a 5 piece design. Front splitter, rear diffuser, middle tray, and 2 side skirt trays.

I also found pictures of a 1990's DTM car (Deutsche Touring Masters) that looks killer and is a good design inspiration. These cars did not win much in the series but they got the cool factor down for sure. I'd love to make a front bumper similar to the one shown. Just look at that wing... From what I understand it's a modified fiberglass GT wing with a huge upward slope molded into it, along with a big diffuser out back.