front disc brake calipers not releasing?

Just got my CJ5 back from the alignment shop after some suspension/differential work. I had power locks installed. Well the alignment went well but they mentioned the front calipers are holding pressure on the rotors as it is hard to turn the wheels. I noticed this previously as I can park or idle on an incline and the 57 won't move/roll. Any ideas on what could be the problem?
1) could it be the rod from the pedal to the MC needs adjustment (as there is no play, as soon as you push the pedal in the brakes start to engage)
2) wrong MC? I heard there were differences for a disc/drum combo system. (does a drum MC keep pressure as opposed to the Disc MC?)
3) pads too thick? Such a thing?
4)adjustment on the caliper?

Thanks, I have a 57 CJ5 with front disc conversion and rear 11 inch drum conversion. Dual reservoir MC from Herm and brakes from him. All new lines, has a proportioning valve in the rear line.
Paul

 

1-That would be the first thing to check.
2- Quite possible, especially if the brake lines are connected wrong at the master, as in the line that's supposed to supply pressure to the rear is supplying pressure to the front. A lot more common mistake than you might think.
3-Possible
4-Not possible, no adjustment
There are a couple of other possibilities but I'd eliminate 1 and 2 first, especially number 1. Easy enough to check, disconnect the push rod at the pedal, jack up the front and see if the wheels spin free.

 

If your MC or proportioning valve has a built-in residual pressure valve (RPV), you may need to either remove the RPV and install aftermarket disc RPVs from Wilwood, or swap out the MC/proportioning valve for a disc/drum unit. Just swapping discs but leaving the stock MC/proportioning valve in place will cause the symptoms you mention. HTH, YMMV.

 

Are the brake hoses old? I have had them come apart on the inside and act as one way check valves to the calipers on an old F150 before

 

Had the same issue with mine.I ended up doing a caliper rebuild and it solved the problem. Just a suggestion.
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Had the same problem when I replaced master cylinder. My push rod had a mushroom head on the shaft that fitted on a slotted washer that was held in the master cylinder by the c clip. The slotted washer needed adjustment so cylinder could make a full return upon releasing the brake allowing return flow to the cylinder otherwise the front line remained pressurized. As previously mentioned I to has to remove the residual pressure valve in the side of the master that went to the front disc brakes

 

attached are some pics of the rod from the pedal and where the pedal comes through the floorboard. there is a spring that holds a felt pad on the underside of the floorboard. Is it me, or does there seem to be not much adjustment on the rod from the pedal to the MC? What is it supposed to look like? 2 thoughts come to mind, remove the spring and that would allow some more free play in the pedal if the spring is keeping pressure on the pedal (as if there was slight pressure on it) or adjust the rod somehow. any guidance on how to adjust it?

Brake pedal at MC

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Brake pedal at MC

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where brake peal comes through floor

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felt/washer/spring

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Take the spring out between the pedal and the floor board. The position it's in now is going to try and apply the brakes. Probably your problem. You also have a plate and what looks like an insulator of some kind making the problem even worse. Those don't look stock to me and are pushing the pedal down trying to apply the brakes.

 

Ok....Whatever you do(somebody mentioned this above)...DO NOT USE any other push rod retainer you had from before.

Did you see that black washer with the 4 teeth on the inside that came in Herm's M/C when you took off the snap ring? That M/C is designed to use that thickness washer. If you put ANY other kind of retainer in that M/C, it won't let the back pressure off the front tank and your jeep will hold brake pressure. If it was anything like mine, the more it worked, it held so much pressure, the front brakes locked up.

If you don't have a 2 piece push rod, just take that black retainer and cut it with a pair of tin snips and bend it back over the rod....or just don't use it at all. The constraints for that M/C don't allow for much play behind the snap ring

I went round after round with Herm on this. He ended up making me call Raybestos. There is no removable residual valve on that M/C. It is built in with 2# in the front and 6# in the back.

Also, I had to put in washers between the M/C bracket and the M/C. When I took off the center floor, it had enough freeplay, but when I put back on the floor, the floor took out all my freeplay. If you have to do this....good luck getting in washers on the outside M/C mounting bolt. I ended up supergluing 3 washers together and dropping them in with a magnet. It's real tight between the frame rails and that M/C braket, Especially with the body on.