Brake Caliper came off!!

I was driving home yesterday and my car lost braking power completely. I was lucky I only had a few miles to go or I would have been in serious trouble. I had to use the parking brake to get home. I don't have any idea what caused it to do this, but the two bolts holding on my rear brake caliper are completely gone. I replaced my rotors and pads including a rear disc conversion months ago. I tightened everything down according to the Helms manual. Is there anything that would cause this sort of failure? I did just add front and rear strut tower bars, but I don't know how that could do anything.

Thnx in advance.

first that came to me was, was there any noticable vibration after u swapped the rotor?

Did you use a torque wrench?

I don't remember there being any vibration. The swap took me a couple weeks(couple hours a day every second day or so...), so I wouldn't necessarily notice any small differences. The car seemed pretty loud the day it happened on the highway, but I was on a grooved road, so it's hard to tell if it was caused by the car.

I did use a torque wrench. It is kinda long so it was hard to use, but I did use it. Could be that I didn't get a real good application since the location was hard to get to.