Warped Rotor? But how?

2009 Honda Accord 5 speed

I parked my car for a week at the airport in late spring (no snow). I set the handbrake of course.
When I retrieved the car and pulled out of the spot, there was a big thump! as if I had run over something. I got out and looked, there was nothing.
As I drove towards the exit, it felt as if I had a flat tire. I got out and looked, all were ok.
It continued to feel as if there were a flat tire for some time as I drove. It slowly got better over the following week.

Ever since then (it’s now October), it has felt almost like I have a warped rotor. I can hear a faint sound from the front that speeds up and slows down according to my speed. But I do NOT feel it in the brakes, nor in the wheel, as I have in other cars when I had a warped rotor. The noise has abated over the time period, but has not gone away. Braking performance seems fine.

So what’s going on?

Your tires developed a flat spot, that is they took a set from being in one place for so long. It should work out after a while, but I would suggest that you get the tire pressure checked with an actual gauge and get them pumped up to the specified pressure. Chances are that at least one tire has lower pressure than you think. This time of year, tire pressures start dropping as the air gets cooler.

Or it could be that the emergency brake (which clamps the disc pads on the Honda) froze to the disc from corrosions, broke free (the ‘big thump’) then continues to provide an uneven braking surface. I’d have the rotors sanded to see if the that area can be removed.

Yeah I agree with both. Pad frozen to the rotor and flat spots on the tires. I really would try to avoid leaving the brakes on for extended periods like that.

Did it rain on the car while parked? If yes, likely the “rusty rotor” scenario. Pads and rotors look OK? Drive on.

I did leave one thing out, not sure if it’s important. The day after my return, when I went to back out of my garage, I had the big thump again. But not the succeeding flat tire feeling. Never got a 3rd thump.

Also if it’s important, I’m not dainty with the parking brake. When I set it, it’s ON!

I initially had thought the flat spot was the answer, but I was parked for only a week, and it should have worked itself out in the 5 months since. I do check the pressure. I also wondered if the parking brake and/or the rear calipers were sticking or frozen as you say. I don’t know if you can turn rotors anymore?

for @Insightful, it rains here like it’s Seattle.

I’d jack it up, support it with a jack stand, remove a rear tire, and see if I can observe/feel any irregularity in the disk, sand it off with emery cloth, spray down with brake cleaner, then repeat for the other side.

Your brake pads rusted to the rotors, the clunk, the rotors have rust deposits, the warped rotor feel, time will heal the wounds, at least it did in my case after a couple of weeks of in town driving. The pads sticking and causing an initial clunk may go away if the car is driven daily, Had one work truck any time it sat for 2 or 3 days it was a guarentee.