My path down aero lane has taken a serious turn this winter with the addition of a full underbody treatment. In aero terms, I call this my V3 configuration, as it follows V1 and V2, which were variations on a wing and a splitter.
V1.0 (October 2018) consisted of a Bimmerworld “V3 Carbon Race Wing Medium” and a custom 5” extension splitter. This wing installs high enough that rearward visibility is unimpeded.
The Bimmerworld supplied hardware assumes through-bolting into the trunk lid, but as the fasteners install into closed cavities and would require internal trimming to get nut access, I installed mine with 10-32 rivnuts using the supplied rubber gasket
The upright is drilled for ¼” bolts, but I installed nylon washers to reduce the holes for 10-32 UNF structural stainless hardware.
The uprights required a slight bend adjustment to perfectly match the slope of the trunk lid.
To prevent the wing from striking the rear glass when the trunk is opened, I installed limiting cables.
Adjustment of the wing uses an interesting slot geometry that keeps the wing trailing edge height constant as the angle is changed rather than using one fixed pivot point and one sliding. This may be beneficial when racing in classes with a maximum wing height.
If installing the wing is a 1 in degree of difficulty, fabricating a custom front splitter is about a 3.
The splitter was fabricated from 3/8” HDPE, solidly supported at the back by a bracket attached to the front subframe and at the front by means of fixed stays attached to the bumper impact beam by means of rivnuts and eyebolts. A quick and dirty air dam seal was created with duct tape to seal the gap between the splitter and the bumper cover.
Sorting out the geometry was simplified by making a prototype out of clear lexan.
The actual design was modeled in CAD and the finished splitter was cut on a CNC mill. Given that splitters are consumable, and I figured I would be going through a few different versions, having a quick way to make identical or adjusted replacements is useful.
Prior to driving the splitter, I asked a friend to give it the standard “stand on it” proof loading.
