Thumping in my Civic

This issue with my 2003 Civic Coupe has blown my mind. It’s a clutch, just so you know, and when it’s really raining outside or slushy from the snow and I’m driving I’ll start to hear and feel a thumping toward the middle part of my car. Not all of the time, but most of the time. Friends have felt it sitting in the front and the back. The thing is even when I’m stopped at a light in gear or out and the thumping has gotten really bad it sounds almost as if my car is grinding. I want to say the way my car revs sounds different when this happens and I sort of feel like I lose a little bit of power when this happens too. I just don’t know what’s wrong with it. I’ve heard it could be something in my drive train. What do you think?

Either motor mounts / transmission mounts come to mind. Also, the exhaust pipe might be hitting the body.

See, I was thinking it could be something loose too, but I checked and nothing that I can feel is loose at all. And if so, why would it sound like grinding, or as I like to say…sound like death even when I’m not moving?

A heat shield around the exhaust system could be loose. Does the sound increase at certain RPMs? If you bang on the various parts of the exhaust system with a rubber mallet do you hear anything ratling? A muffler shop could put the car up on the air and do a pretty good diagnosis of this sort of thing in just a couple minutes, and probably at no cost.