Cars Edited car falling through ground on start

[sarucasm]

I am currently editing a mod to add a spoiler. I have modeled and replaced the current car's spoiler in Blender. I've also used the AC Car tuner app to make a completely new tune and replaced that tune's Kn5 with the model. For some reason the car decides to fall through the ground on race start and collapse the wheels to the center.

Just to note I've changed the spoiler aero position and somewhat adjust the power.

I'm thinking it was a hierarchy mess up, but I've applied scale and origin points. Replaced again, yet it still falls. Any ideas?

 

[sarucasm]

Update: Replaced the car's data with the original car's and somehow seemed to fix it. I'll look into what I shouldn't change and what I can.