It might be your brake controller that is the real issue with your brake problem. Several members on "Turbo Diesel Register" claim that the best brake controller on the market is a unit that is called "Max Brake". Here is a link to their web site.
http://www.maxbrake.com/
I have attached a thread to one of the discussion on "TDR" website on brake controllers.
http://www.turbodieselregister.com/f...ntrollers.html
I have even read were one former commercial hauler for RV's did not like disc brakes on RV's. He claims that there is a pressure delay in the brake actuation which makes sense to me compared to the drum brakes on RV's, for response time in braking of the RV. The truck will be braking first and then do to the delay in actuation pressure of the "Hydraulic" disc brakes the trailer will finally start to brake.
Jim W.