I just installed disc brakes on the back of my 81 RC. They work like a champ, but noticed that the rear brakes get hot now, when the front ones are cool (seems to be dragging). TSM told me to remove the residual pressure valve found in the master cylinder or combination valve. Well I tore both apart and found no residual valve. I am looking for help on how to find this valve or other ideas to why my rear brakes are hot.