Why is the rum gone?
Join Date: May 2012
Location: United Kingdom
County: Greater Manchester
Rear calipers on 159s have a history of squealing.
When I joined the forum it was a common thread.
The cure is to disassemble the callipers (on the car, no need to remove hoses or anything too technical) with everything in bits clean and clean again, take a wire brush (drill mounted if you have one) to the callipers where the pads touch (the slider bits) clean the stainless steel frames.
Basically clean everything, don't bother with the piston, it's the bits that the pads sit in that corrode and causes them to stick.
I had exactly this issue about 2 1/2 years ago, a gentle application of the handbrake stopped the noise (so you know its the rears)
took about 30 minutes to clean both sides with drill wire brush and soft hand brush to remove all the dust the wire brush creates, I used copper grease at the time, but have since replaced pads and discs dry with no noise.