Ringing brakes: 1983 300CD-T (123.153)

[dogguy]

Over the last several months, the brakes were giving off that familiar (at least to me for the last couple of decades with this car) ringing sound indicating pad wear. It turned out to be the rear pads that were down to their last 25% or so.

Upon installing new pads (including using the anti-squeal paste as usual), one of the anti rattle springs fell apart. I replaced both. After all was said and done, however, I still get the ringing sound for the first mile or so in the morning on the way to work and in the afternoon on the way home. After the first mile or so, no more ringing.

Questions (rear calipers are ATE):
1. Is the ring (like a pencil eraser's ferrel) that is located around the head of each pad retaining pin responsible for the ringing sound?
2. Is it possible that the pad retaining pins (maybe the culprit is the ferrells?) wear down ever so slightly, become loose in their holes over the years, and thus the pins generally and the ferrells specifically, rattles just a bit and this is the source of the problem?

Perhaps the issue is: Once the brakes heat up enough, the metal pad retaining pins (and ferrells) expand ever so slightly and their looseness is overcome and thus there is no room for the ferrells to begin their ringing?

I'd appreciate any insights on this one. Thank you.