Changing rear brake pads for the Proton

Since about a week ago, I noticed my wife's Proton persona will produce a deep grinding sound from the rear whenever I brake while reversing. I assume that is because the pads are worn despite the car being just 22k kilometers old, even though I can't really observe the pads through the wheels and the calipers.

Deciding that being safe is better than being sorry, I purchased a set of OE rear brake pads from my usual Brembo dealer and headed to the nearest workhop to get them replaced.

After the mechanic removed the old brake pads from the caliper, I quickly noticed that the problem was not a worn brake pad - as you can see from the picture below there is still plenty of pad material left (Left arrow = pad wear indicator; green arrow = brake pad level).

Of course this makes perfect sense because of the low mileage of the car plus this being the rear brakes, it would be very abnormal for the pads to wear so quickly. So what made the sound? Apparently it was because the pad material has glazed over.

It is not that obvious in the picture above, though you can see some shiny bits near the edge. If observed at an angle I can clearly see the pad surface has become reflective and shiny, not unlike the example below I found from the internet

(image credit : rennlist.com forums)

A glazed pad means the pad surface has smoothen out itself and lost part of it's friction properties, usually caused by improper pad bed-in, overheating due to aggressive usage or riding on the brakes while the car is moving.

In the end, despite there being still plenty of pad material left, I decided to replace it anyway due to safety concerns, as well as the fact that these stock pads are incredibly dusty and performs terribly anyway.