According to the Cleveland manual for the 30-55 brakes it’s 75-80 inch pounds (or 8.5 to 9 Nm if you have a metric torque wrench) – dry.
The manual also warns that “Overtorquing can cause depressions in the brake cylinder leading to dragging or bound up brakes”
I know Beringer has an EASA STC for the PA28. Do you know if this kind of upgrade makes sense in terms of reliability and reduced maintenance ? Or does it just improves the braking action ?
It seems to me that those auxiliary systems of GA aircraft were/are designed cheap and support is ahem limited 
