I notice a low rumbling noise behind me on the left side, but only intermittently. It happened on Wednesday afternoon every time I braked…but not on Thursday morning or Thursday afternoon. The mechanic who drove my car on Friday morning didn’t hear anything at all. I just got new tires, but otherwise nothing has changed. The mechanic said my brake pads looked good but that the brake drum may be out of round. It’s a 2004 Honda but only has about 75,000 miles on it.
You probably need to machine the drums at 75K miles.Sometimes drums can become rusty and can form a lip at the edge.That can makes noise if you let the rust grow.
If your car has rear drum brakes and a hand brake lever between the seats, you can apply the rear brakes only with that hand brake. Keep your finger on the button so you can vary the force on the rear brakes. Don’t do this in traffic - your brake lights won’t come on. Do you hear that unusual sound?
Sometimes rust builds on the rear drums and you can polish it away by doing this.