For close to a year I was fairly certain I had the defective exhaust hanger. The rattling noises from the front and underside were just like the recordings I heard of the bad hangers.
So....
I knew I needed discs. It had that distinctive grinnnnnnnding sound when braking.
Last weekend I decided to install the new brakes. It was 4c out. Yuck.
So, new rotors, pads and hardware. No more grinding noise when braking, obviously.
But get this, No more exhaust hanger noise. My defective worn out discs aped defective exhaust hangers for a year. The noise, the rattling, got worse as the year wore on. I never in a million years imaged it was the braking system. You would not believe how worn down my discs were, the metal backing plates were nearly gone. A few more days/weeks/panic stops and the backing plates would disappear.