Scout rear disc ?s

I have swapped a scout 44 into the rear of my jeep (76 cj-5) and have kept the stock manual brake master cyl. It stops great, I don't have power brakes but my problem is that I am getting rear brake drag. It takes a while and releases but it gets pretty bad over about 3-4 miles. I am running '78 front rotors and 79 cadillac calipers with the built in E-brake. I can't figure out the drag so if anyone has experienced this I could really use the input.

 

Are you still using the stock proportioning valve? If so they have a built in residual pressure valve which is set up for drums (about 10lbs) vs 2lbs for discs. You may be able to mod the stock valve by removing the o ring, not sure on 76s? Or you can run new lines with an adjustable proportioning valve for the rear brakes and use 2lb inline Wilwood residual pressure valves if needed front and/or back.

 

X2 on the residual valve. IIRC it is in the master cylinder. I heard that you can remove it by running a screw into the valve after disconnecting the line and pull it out. Then put in the 2lb residual from willwood.