Ragdoll spazzing out when arms flail behind him

As the title says, The level is the 3rd one "Need for Speed" i built a simple vehicle using a basic frame, shocks, steering wheels up front and two rockets. anything above %45 speed the robots arm swing back, then spaz out flailing extremely quickly (I am assuming when they hit a joint limit) every time it causes him to fall out of his seat nearly right after you hit GO. I can supply screen shots if needed