2003 Ford Mustang having problem with rear brakes

always make sure that your master cylinder is open so the fluid has a place to relieve itself when you push the cylinder in. plus video will help.

this will show ho to retract the caliper

https://youtu.be/j8YwfSKEzZo

let us know

Hello,

In order to retract the rear caliper piston, you will have to use a special tool.
This tool will line up with the notches on the face of the piston. Then you will have to turn the handle of the tool to retract the piston back into the housing.

Here is helpful video:

https://youtu.be/j8YwfSKEzZo

https://www.2carpros.com/articles/how-to-replace-rear-brake-pads-and-rotors

I have attached the pad replacement and piston retract procedure below.

Please let me know of any questions.
Thank you.