I have an '85 CJ8 I've been building up. Completed 350 TBI w/700R4 to dana 300 swap. Finally swapped rear axle to a dana 44 w/ explorer disc brakes. Rear brakes are not releasing (dragging). I'm running stock discs up front, stock MC & booster, stock combo valve. I thought maybe I had a residual pressure valve in the MC after reading some posts, but when I pulled the rear line and the seat, there was nothing behind it (no valve). Is there a residual press valve in the combo valve? Is there a combo valve from another jeep that is designed for dis/disc that will attach to my lines? Or do I need a custom disc/disc combo valve? I've read a lot of posts, but most discuss poor pedal or no brakes not dragging rear discs on a CJ. Thanks for any help.

are the shoes for the parking brake connected? perhaps the em brake is dragging and not the pads?

are the shoes for the parking brake connected? perhaps the em brake is dragging and not the pads?

Thats what I would check first. And you may need to get an adjustable proportional valve to get the correct pressure to the rear discs once you have figured your drag issue out.

coming from a new guy,
try master power brakes out of Mooreville NC. They have the expertise that may help.

good luck

It's possible your combo valve has a residual valve built in. If you had disc/drum before the rear disc conversion, you need to either replace your combo valve with a disc/disc unit, an adjustable proportioning valve, or at minimum, gut the valve you have. The disc/drum unit does not allow sufficient pressure to properly actuate the rear discs in all braking conditions; however, as you probably already have learned, the absence of a proportioning valve could lead to the rears locking up before the fronts, resulting in "swapping" ends in a high-speed panic stop.
As far as the rear pads dragging, more info is need.
Are both pads, on both rotors dragging? Or is it only the inner pads?
Did you use flex lines between the calipers and the brake hard-lines?
Are the rotors re-drilled Explorer units? Year/model?
What is the distance between the axle flange mounting surface (where the backing-plate mounts) to the axle mounting surface for the rotors? I ask that because it's possible the rotors aren't properly centered, if that distance is not the same as the design-distance considered when the caliper mounts were manufactured. I'm not positive, but I believe the caliper mounts were designed for a distance of 2.5 inches. If you are using after market axles, the axle flange may be thicker, moving the rotor outward from the "designed" center line.

Thanks to all for your time. Still havent figured it out. I loosened the ebrake line and let it hang slack. Also took both rotors off to make sure nothing broken or binding, all looked fine and rotors slide on and off easily. Also adjusted the star adjuster bolt way in to make sure ebrakes are not the ones causing the drag. The pads seem to be centered on the rotors and as far as I can tell both sides of both L & R rotors are making contact and dragging. As for the year of the explorer brakes, I'm not sure. I bought the custom built axle from Sam's Offroad in Tulsa (and they've done a bunch of them). I forgot to measure the distance from the axle flange to the mounting surface for the rotors to see if it's 2.5" when I had it apart, next time I'll check that. I've been looking at Vanco's vacuum kit for cjs (looks like a corvette MC and a 9" GM booster). It's expensive but it would sure save time. Maybe that would solve my drag and also give me the stopping power that some people seem to have after a disc conversion (it sure would suck to solve the drag and then not have good braking). Besides that combo valve (although I can't confirm that there is a residual press valve in it), another possibility is the braided SSt line that connects the hard lines from the combo to the hard lines on the axle (it's a few years old). The rubber flex lines to each caliper are new.

Check on your master cyclinder in the rear port where your line goes on there is a pressed in restricter that is used to keep presure on the rear brake shoes so its faster to get the brakes to come into play to overcome the springs. You need to remove this, use a sheet rock skrew and thread it in and use a pair of vise grips and pull the restricter out . This should solve your problem. It did on my 1974 CJ-5. Let me know if this helped.

Dave