[jeffcoslacker]

Those rears have to rotate the piston as it applies, and that is how the parking brake effect is achieved. And because of the relatively light application of the rears, and the miniscule amount of rotation required to apply them, the movement was just not enough to make them stay free. With a driver that is not very aggressive with the brakes, the amount of fluid pressure required to rotate the rear pistons was usually not achieved, and most people can't feel when the rears don't work, as the front do an adequate job for most conditions. I thought I saw a revised proportioning valve that allows the rear to apply with more force to offset the problem, you might ask the dealer.