A friend of mine who at one time was a rep for a performance brake company once told me that his wife, who happened to have a performance car would often complain that the brakes were squealing, he would take it for a drive (re-bed them!) and give it back to here all quiet again... until next time! His explanation was as they were performance brakes and she was just using the car as a daily driver the brakes were glazing over and just needed to be re bedded to be all good again. Food for thought?
It is just something I have always bared in mind regarding brakes but I don't think this is your problem, that rear caliper needs to be ruled out as the problem, good luck it is a very frustrating problem for you so far.
That left rear caliper is likely not long for this earth...I checked my local Mopar parts online store (web front for dealership parts department; why can't they sell the parts from the counter at the same reasonable prices?
), and I can get a reman caliper from them for $80 or so. So if I end up replacing that puppy, I'll go with one of those Mopar reman units.
On a more esoteric note though, I've been going over and over this problem in my head all night. I just cannot envision how that caliper (or one of its associated parts) is vibrating at a high frequency and causing the squeal under the conditions in which I hear the sound. I have no doubt it is, I just cannot wrap my mind around how it's doing it. Soooooo
, I've got an experiment lined up for the Bacon Hauler's brakes today, and if it goes well, I will not only come away with a better understanding of how those brake components work together to put the Whoa-down on the car, but hopefully I'll also come away with the answer as to what's causing the noise, and thus what needs to be fixed to stop it.
Stay tuned, I'll post up the outcome of the sciences I do today; hopefully they will be good'ner a sum-beech!
(and if no further posts are seen from me, it can be assumed that my sciences went bad and severely injured or killed me, in which case i'm going to need somebody to make sure some good old Jason Boland and the Stragglers is played at my funeral!