Both of my rear brake calipers hung while traveling in mountains. Both so hot that I had no brakes. Had not been riding the brakes. Had to bump them when someone pulled out in front of me. Never noticed them hanging but smelled them and then hit the brakes and no brakes. They were so hot that they blew the valve stems out of both rear tires. Once they cooled, I had brakes. What would cause both to hang up at the same time?

 

• Both calipers having the same problem at the same time, frozen pistons, frozen slides, bad hoses, etc.
• Collapsed rear brake hose at the frame to axle drop (driver's side).
• Rust build-up between the master cylinder and hydroboost from a leaking rear seal in the master cylinder (if you have a diesel truck).