Mystery Brake Problem '07 Ford

So here is the deal… my front left brake pads shift around inside the caliper causing squeaking noise and rattling when I hit bumps… so I’ve replaced the caliper, the caliper bracket, the hardware, the pads (twice), lubed the parts, bled the system, and still have the problem… what I finally realized is that the caliper piston slightly retracts while driving which keeps the pads loose… in addition, when I press the brakes since the piston is slightly retracted I hear a Clank sound of the piston slamming the back of the pad… now my question is- why the heck is this happening? The pedal is a little soft… Its only on the front driver’s side…

It could be a bad check valve in the master cylinder. It is supposed to keep some hydraulic pressure to the calipers are all times. Another thought would be a bad wheel bearing.

Sounds like some other problem other than the brakes. How about strut mounts, ball joints or some other suspension bushing? All these can produce a clank upon braking. I do not believe that it is humanly possible to hear the point of contact between a pad and rotor.

“I do not believe that it is humanly possible to hear the point of contact between a pad and rotor.”

Good point.

A slightly warped rotor could be working the pads away.
Maybe you’re hearing is the pads taking up slack from the rotor.
Try swapping rotors.

when I bleed the brakes the problem temporarily goes away and the pedal is hard… but then the system must slightly lose pressure and the pedal softens… I turned the rotor once and then replaced with a new rotor… I’ve gone through all the points you mentioned above, and yes, the noise is the pad slamming against the rotor once the piston makes contact with the pad… and when I remove the pads to inspect you can see the chaffing of where the pads are moving around within the bracket… its unreal how no one can really figure out this problem… I searched some other forums and noticed on a honda forum this kid was explaining exactly the same problem I had but no one had the solution… I’m going to inspect the check valve on the master cylinder…

What kind of pad, OEM or aftermarket?

Yes, the pads are OEM… Ford did all the work… we started with turning the rotors, then replacing the rotors, then brakes, then hardware, then caliper, then bracket etc etc etc… they just gave up and the tech said he didn’t know how to fix it… I’ve tried going in and adding extra lube etc but nothing has worked… for some reason the system is not holding the pressure… if I gently hold the brakes while going over bumps there is no noise because the pads are held in place…

All that’s left is the master cylinder.