TitanBlue said:
What goes wrong with them and why. How are they constructed differently? I have a set on the front already.
nothing goes wrong with them per say.
They are more susceptible to binding though, and the steel can actually wear. It's nothing to be alarmed about, but you should definitely know to inspect them periodically.
I had them on a bmw I had years ago and loved them, until one day it binded and left me without brakes. Lucky enough i was not injured and no one else was as i found out about the lack of brakes pulling out from my driveway.
Not a big deal, just check them for wear and replace if necessary. I would probably put them on my next sports car, the upgrade is worth the hassle of inspecting a couple times a year.