Loud hard clacking sound

[Full-Throttle]

Sometimes when I brake hard i get this really loud clacking sound and the bike is rattled, but im not even sure if its consistent with breaking hard or if its some other combination. If this were to happen at a higher speed I think i might be toast. However I tried breaking hard at a slower speed to see if i could recreate the problem and it doesnt happen. One time i was slowing uphill on an on ramp, the other time i was in a parking lot and decided to give it some gas around a corner, nothing insane but then when i was using my brakes it happened again.........any ideas?

the bike is my 2001 ninja zx-6r

[94rf900r]

not real sure what to think with that info but i had a quad a while ago and a bolt fell out of one of the calipers so evertime the brakes were applied the capiler would clack because it was moving. i doubt thats what it is but thats the best i got for you for now