knocking from back of 6th gen celica?

[cookci]

Ive got a knocking noise coming from the back of my celica.

it happens when your going at slow speeds and going over slightly rough terain e.g. pebbles etc.

big bumps dont reproduce the sound.


the sound is kinda of deep and sounds like its coming from inside - which it cant be cos i removed everything at one stage!


please help

cheers

christian