I just did a rear disc conversion on my 96 civic ex. I put the discs on and bleed the brakes like i was supposed to. If i go faster than 30 mph and brake there is a strange spurring or rattling sound coming from the brakes. What could this be. i have no idea.

 

wheel bearings maybe?

 

did you replace the pads and the anti rattle clips? How about the adjustment of the ebrake was it done? Did you clean and relube the caliper slide pins? Is the ebrake mec working in the caliper? You could also have a few bolts that need to be re torqued.
EDIT: 1 last thing if you replaced the rear disc with an xdrilled rotor they make a noticable bit of noise on the rear of the car. At least they do on my hatch back

 

I did put xdrilled and slotted rotors. Why is it making that noise. i have xdrilled and slotted rotors on the front and they dont make that noise.

 

I don't know why it must have something to do with the xdrill and the fact the rotors are non vented. The only way that I was able to solve it was to change back to blank rotors. I wanted the extra cooling so i just left them on the car