The thump would be a bad strut. Try this. Go to each corner of the car and start pushing down on it and letting it come back up. It should stop right away. If it keeps bouncing or is easy to push down on, it is a bad strut.

 

What would it cost me to get the springs to my door? Location, US: 27284

 

Make sure you change them before you snap springs, i snapped 3 on the way back from out of town because i had bad stuts on a bumpy road. I picked up 4 stuts with springs from junk yard for $100, i think it was like 300 just for struts new from advanced auto parts.

 

My FIL is going to call around to junk yards tomorrow. That would be nice to get the struts and springs for that price. I just hope that used struts last a year at least.