OK, I searched NHTSA and found their research - they are saying discs stop faster in their testing. They used real trucks and real drivers to do the testing, no computer simulations. A total of 108 drivers were used. I got tired of reading and just copied the important details -
*Edit - read further into it - The stopping distance from full panic stop numbers are from a real truck, the 108 drivers were to test reaction time using a simulator
Anyway, i was completely wrong about the numbers- they aren't cutting in half from 600 to 300 feet, more like 30%.
Full panic stop from 60 MPH -
Regular S-Cam and drum - 317 feet
Enhanced S-Cam and drum - 252 feet
Air disc - 222 feet
http://www.nhtsa.gov/DOT/NHTSA/NVS/V...ons/811367.pdf
This document has the research on stopping distances - the previous one was just research on how drivers responded to better brakes
http://www.nhtsa.gov/DOT/NHTSA/NRD/M...OTHS809700.pdf