My toyota rav 4 2002 has been making noise when driving over uneven road surface or bumps. The noise is so loud that you can even hear it when you play the music. The noise, which sounds like a loud knock, mostly comes from the rear, but sometimes you can hear it coming from under your seat. I've checked with an local authorized toyota garage, but they couldnt find anything wrong with it. Does anyone has any suggestions? Cheers.