So i replaced all rotors and pads 6 months ago with powerstop drilled and slotted rotors and their pads(it was a kit). Whenever i get in and drive after the brakes are cold, i get this squeal/whining noise from the passenger rear wheel. After i roll about 20-30ft and ride the brakes, it goes away.

any idea as to what may be causing this and how to get rid of it. thanks!

 

i got ebc slotted and dempled all the way around and mine squeal too and it drives me fing nuts

 

Check what combination the pads are. Ceramic pads are quiet and metallic pads tend to get noisy. Unless debris got stuck between them. Usually they disappear when when they get un stuck.

 

mine are ebc green stuff and all clear

 

Had ebc green for over 10 years and at times sounded like the titanic when squeaking. Then calipers got stuck and replaced pads with advance auto duralast gold and it was the best combination i had until recently rear piston got stuck again and ate the rotors. Replaced all with the ebay cheap$135 complete ceramic set and i am very surprised in stopping the truck with LT 175/65/18 duratrac and its quiet, no slots nor dimples.

 

Inspect brakes when cold on RR yet? I'd look at LR at same time to see if RR caliper not as free to move. And compare any drag on rotors.
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#1: remove rear brake pads and apply Disc Brake Quiet product ( CRC Disc brake quiet 05016 - Read Reviews on CRC #05016 ) to the *back* side of the pads, NOT to the wear side.

Allow that product (no affiliation) to dry or become tacky (overnight is good). Now reinstall your rear pads.

#2: if the squeal continues on your next test drive, stop your Disco, put it into Reverse where safe, gas it up to about 10 mph and slam the brake pedal to the floor for a full emergency stop.

Now take a test drive.

If the undesired noise continues, turn your rotors down and repeat step #2.

If the noise still persists, go with new rotors and new ceramic pads.