1999 Dodge 2500 diesel 2 Wheel Dr. rear brakes will not perform have changed the wheel cylinders to a larger size which has been suggested still unable to get any increase in performance in the rear brakes I have eliminated the proportioning valve and replaced it with a adjustable rear brake bias valve I have adjusted it to its max pressure and still no lock up of rear brakes the ABS this truck is equipped with is the rear brakes only and that’s been bypassed doing some research it’s been suggested to change the bore size of the master cylinder especially with increasing the size of the rear wheel cylinder truck has hydroboost any suggestions of what master cylinder I could use in this application or any other ideas