Guys, I've read through every FAQ, tech link and done numerous searches, followed all of the previous suggestions and my problem still exists: I have a 1974 FJ40 that had drum brakes. I bought a set of axles that had been converted to SOA with disc brakes on the front using mini-truck parts on an older style axle housing. I think it is an older axle because it uses the 9mm brake line fittings at the T-block and calipers. I converted the rear axle to disc using a JTO kit and I installed a new JTO's disc master cylinder at the same time. The brakes work great. But after driving a few miles and making a few stops you can feel them start to drag. This will get worse with a few more stops to the point that the vehicle cannot move. The only way to move the vehicle is to release the line pressure by removing a small plug on the bottom front of the MC. You will get a few drips (maybe a tsp of fluid) then the brakes will release and everything will be fine for a few more miles/stops until it eventually locks up again. I have adjusted the pedal rod under the dash so far that if I go any further the brake lights stay on all of the time. I can see the pedal move a good 1/4 inch or more before the black plunger on the brake booster starts to move. The pedal has a good, strong return spring on it. I pulled the MC and removed the rod from the booster that has the adjustment nut on it, and I tightened the nut down as far as it will go. It tightened down a good 3-4 full turns. I have included a picture of my MC. As you can see, there are no large nuts where the brake lines attach so as far as I know this unit does not have a residual valve in it. I have circled the plug that you take out at the bottom front to release the pressure. It looks like there is a line coming from it but there isn't. I have even taken the front and rear lines off at the T blocks to see if there are residual valves in the T-blocks, and there doesn't appear to be any. I THINK its the front brakes that are locking. I installed a proportioning valve today and adjusted it so minimum pressure was going to the rears and maximum to the fronts. Setup that way, the brakes will start to drag and then lock completely quicker than before, so I think putting the extra pressure to the front makes the problem happen quicker. But to be clear, the brakes were dragging and locking up before I installed the proportioning valve. Is there a residual valve in this MC I am not aware of? If so, how do I get it out? Do I need to take the rod out of the booster and cut it even shorter? I am at the point of putting my old 2 reservoir MC back on. I did pull both of the residual valves on it, but its in pretty sad shape. I would much rather figure out what is going on with this new MC? Any ideas?