remember that the 75 has equal weight front and rear so the rear brakes do work harder than on other less balanced cars. Heat build up would be a factor, but could be caused bed badly adjusted brakes binding
Do a search for 75 manual's on this site there a website to get them from... (on laptop so don't have link)
It's easy , well 75 easy, if you know what I mean.
but it's the pad clearance adjustment that scares me. 4 adjuster's to set a 1mm(or thereabout's can't remember exactly) and one adjuster turns anti clockwise...
I still wonder why alfa did'nt use the sud's front brake calipers on the rear of the 75. the 308 ferrari did