Brake caliper pistons not retracting

[68Cuda]

Originally Posted by J-440

Am using braided steel line with no tape whatsoever. The outside pad slides out no problem, but the inside pad I have to pry out. The pistons are only about 1/8" sticking out on the defective side, the other side the pistons are flush with the caliper.
What causes the pistons to retract anyway? When you release the pedal, is a suction created to draw the pistons away from the pads?

The flex of the square O-Ring seal and the knock back from any rotor run out is what draws the pistons back. If it is easy enough to swap the caliper left to right then try that to determine if it is caliper or the system. (Are your bleeders and bypass easy to swap) Does your mount have shims to center the caliper? Sounds like you might be off center also. All this stuff is harder to troubleshoot when you have to rely on someone else to look and touch...