i have had clattering brakes for some time. They worked fine though, Just stripped the front end down and as someone was walking past they said i had a rubber pad missing of the back of the brake pad. The piston bites into it and stops the pad from moving up and down in the caliper. went and brought a new set of pins and springs and asked for the rubber pad. They are not included in many new brake kits you have to get them seperate. Got home cleaned back of pad and stuck rubber pad to it. refitted brakes. The work a treat now no more clattering and slighty improved braking.

Interesting point! i have the same "clatter" on my front end,
I need new springs anyway, as mine have corroded away!