Well before I added the credit card shim, my car wold rattle on every pressing of the clutch, every little bump, and sometimes just rattle along going down the street. That is of course until it got hot. About 10 minutes.
It's come back now a bit even with the credit card, but not nearly as bad. Mines wedged under the tower brace on the outboard side nearest the hood hinge. My passenger side has no room for a credit card, but I did wedge a knife blade under there. I would say that did nothing, but I had very little noise on that side anyway.
When it was bad, it was bad. Loud, loose, embarrassing, and gave the impression of something hat was not even SAFE. Like falling apart. But then it goes away when it gets warmed up good. Some smart car guy should be ale to figure it out just with that. I'm gonna call the guys on car talk on PBS....hey, we should all do that:) someone would get through I bet.