My car used to make a ton of noise when hitting even small bumps. Driving on gravel for example, made my rear end turn into a zoo of honks and squeaks and thunks. I've cleared most of it up, but there is still something that clunks at every tiny bump. I'll list some of the sources that I've found and fixed. The exhaust--one of the hooks broke and would squeak as the exhaust slid up and down along the rigid hook. Exhaust--the bung for the O2 sensor was loose and would rattle out of place on a bump and then rattle back into place as exhaust vibration got to it, so I added heat resistant RTV. Rear camber arm--the bushing attached to the cars understructure was/is dry, so squeaks/groans when I hit a deep bump. Every couple of weeks I loosen the surrounding bolts and hit it with silicone spray and the noise goes away again. The rear sway bar links were adjusted too short so when the car was on the ground, the rear sway bar and the camber arm would rub, this was a tough one to find. I had to feel the rub point, blind, because when on a lift, the two parts were decompressed and didn't touch. My last noise is a mystery to me. I hit the rear axle with a rubber mallet and it gave me a similar sound, but I don't even know what that implies.