I am an idiot. I was so excited today about installing a cold air intake on my Ford Focus. I was going to do it all by myself and prove that I had at least some mechanical aptitude. I never even got as far as opening the box. I removed the strut tower bar, then removed the decorative battery cover and unhooked the battery. When reattaching the strut tower bar (in retrospect, I'm not sure why I reattached it at all), I sheared off a bolt. These bolts are what holds the MacPherson strut to the body, and are quite important (if, that is, you like having all four wheels on the ground).
In the course of getting this fixed, I discovered that my Geo Metro suffered some horrible abuse when it was on loan to my sister recently. It now makes horrible noises at anything over 30 miles per hour (louder and worse than the noises it makes just by virtue of being a Geo). The service department of my local FoMoCo dealership assures me that the Focus is safe to drive for the time being. The suspension will be fixed on Monday, along with my 3,000-mile oil change (sob, the car was so young!). I had hoped to attend my first autocross on Sunday.
Today's moral is this: always use a torque wrench. Ratchets are not for torquing things.