I took my calipers and brake pads out in the passanger rear to replace a wheel stud. Anhow I put everything back on and now everytime I press the brake and hold it it makes a sort of knocking sound...any ideas?

 

something is not tightened properly or you forgot to re-attach something.

 

I took it all apart and everything was secure and back on.....I am still able to break real hard and what not but when I hold the brake a slow speeds I can hear a on and off knocking sound...

 

The two bolts (sliding pin bolts) that hold the floating caliper on are specific, (top and bottom) if you reversed these it could be the issue. I don't remember how to tell top from bottom but I do know they are slightly different. I did this once and was getting a wierd scraping noise at low speed braking. (less then 10mph).