This is a good article on disc brakes, but they don't give the magic number you are looking for.
http://www.4wheeloffroad.com/techarticles/drivetrain/131_0708_4x4_disc_brakes/index.html

This company has great info in the FAQ section, and also on their own forums. I have purchased stuff from them, with great results and excellent service.
http://www.hydratechbraking.com/

From: http://www.inlinetube.com/
"Disc brakes require about 1000 lbs. of pressure and the drums use about 300 lbs"

That still does not give you a design value, as you need a factor of safety and an absolute max pressure, not a "requires about..."

Grigg

Last edited by Grigg; 01/01/2008 4:18 PM.