I have just finished putting disc brakes on my 1963 valiant. It took a long time but all went well, used parts from a 1974 valiant. Problem the caliper will not back off. I have taken the caliper off and back the piston back and try again. same problem. Jack the car up and could not move the wheel by hand. Open the bleeder valve which helped.
Is it a bad calipers or the power brake unit.
Both wheels act the same way

Any help Please

Dennis

It sounds like you have a drum brake M/C.....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

^^ As above.... the drum brake MC has a check valve (residual pressure valve) in the outlet(s) that prevents the fluid in the drum brake wheel cylinders from moving back into the MC. This is a problem for calipers as the fluid HAS to flow back from the calipers to allow them to release.

If you have the original single reservoir MC, then that must be changed to a dual MC for the best operation. A dual MC for the disc-drum system will have the correct sized reservoirs for front and rear and will have the check valve for the drum section but not for the disc section. You also need a later model proportioning valve to have the right relationship of brake power front to rear. (There was no prop valve originally on your car, just a distribution block.)

If you have installed the disc-drum MC and proportioning valve, then likely the front and rear brake sections are reversed; the front brakes connect to the rear port on the MC, and the rear brakes go to the front port on the MC.

Just FYI in the last of the A-bodies Chrysler got "cheap" (1973-1976), so some disc brake cars got and actual prop valve body similar to the ones that the E-body disc brake cars got, OR a brass distribution block that was completely hollow and no passage restrictions for drum-drum cars and disc-drum cars...I've used both types on disc/drum cars and they both perform the same in regards to braking with disc-drum setups.

So if the donor had the simple block, installing it would make things really easy to plumb and work with. I can't imagine the need for a power disc brake setup in a light pre-67 A-body...

I've had the same problem on my 65 and it turned out that the pushrod for the master cylinder was too long. I have the 74 manual disc master and one of the 'empty' distribution blocks.

To test, pump the brakes to create the drag, then remove the bolt from the pedal to the pushrod. On my car, the wheel came free as soon as the pushrod could return all the way.

On your car with the booster, loosen the m/c bolts to allow it to slide away from the pushrod in the booster. If that frees it up, you will need to adjust (shorten) the pushrod.

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O==\=/==O

"A mechanic is Somebody."
- Jim Preston

THANK YOU ALL FOR YOUR HELP.
CAR IS UP AND RUNNING STILL NEED A LOT OF WORK
KEEP ME ON THE ROAD
SORRY LETTER CAP LOCK WAS ON

...and that is...the reason we are here, keep coming back, and make sure one more car is still motoring instead of being in a junkyard...

You are welcome.

Inquiring minds want to know what you did to fix the problem!

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014