I have a 2004 fx4 4wd F-150 with 135k on it. I started to have a rattle when shifting into gear under the left side of the vehicle. I inspected it and found the left cat to be rattling, I believe it's specifically the shield around the cat causing the noise as when I put my hand on it, the rattling subsides.

Here's my question: has anyone removed this shield from the cat?

It doesn't seem to be bolted on but rather tac welded to the cat as well as a pinch clamp. I was thinking about cutting the clamp and using a mini belt sander to remove the welds and take of the shield. If the rattling is gone, then that solves the problem, but if it's persistent than I'll have to replace the cat.

 

The top heat shield helps keep heat off your floor boards. The bottom heat shield helps keep heat off the grass maybe. I had one car that I just tie wired the shields together. I've seen cars with out them. I would not change out a working converter just because of a bad heat shield.

 

The heat shield has a good purpose of keeping the heat inside and not transferring to the floor.
WHat I have done on other cars many times is just get a stainless hose clamp of the right size and install around the entire hear shield assy to fix and prevent future rattles.

 

I think this will be my first solution. Thank you both very much for your input.