Originally posted by be459
Someone posted a message in the past saying that sometimes a bad master cyl valve cause the rear caliper problems. The valve sticks closed and does not allow fluid back to the master cyl resulting in brake drag, overheat, and fading.
That particular problem seems to occur on the 126 chassis when the reservoir is "cleaned" with solvent. Due to the reservoir design, the solvent("brake clean")remains in the reservoir for the rear brakes and causes the seal in the master cylinder to swell. I've seen it several times.