Update:
When checked with a laser/IR thermometer immediately after a shudder episode, the right rear rotor was about 100 degrees hotter than the other three, suggesting something was hanging up, so I bought a new caliper, new rotor, new flex hoses, new pads and new parking brake shoes. (I learned from a 1990 Lexus LS400 with a brake hangup that piecemeal replacement can be a false economy.)
Mechanic found that the pivot pin on one side of the parking brake shoes was stiff almost to the point of seizure. Loosening it has eliminated the shudder, and the ride is noticeably smoother. Mechanic decided against installing the new parking shoes since the shoe surfaces, surprisingly, were barely worn. He did install the new caliper, rotor and pads. Still a mystery what was causing the parking shoe to move into contact with the rotor.
Thanks to all for input at the beginning of this thread.
M5Z3M
When checked with a laser/IR thermometer immediately after a shudder episode, the right rear rotor was about 100 degrees hotter than the other three, suggesting something was hanging up, so I bought a new caliper, new rotor, new flex hoses, new pads and new parking brake shoes. (I learned from a 1990 Lexus LS400 with a brake hangup that piecemeal replacement can be a false economy.)
Mechanic found that the pivot pin on one side of the parking brake shoes was stiff almost to the point of seizure. Loosening it has eliminated the shudder, and the ride is noticeably smoother. Mechanic decided against installing the new parking shoes since the shoe surfaces, surprisingly, were barely worn. He did install the new caliper, rotor and pads. Still a mystery what was causing the parking shoe to move into contact with the rotor.
Thanks to all for input at the beginning of this thread.
M5Z3M