Help! brakes on 69 Charger

[pmbly]

I am restoring a 69 Charger. I converted from drum to disk brakes on the front. I also converted to power brakes. I installed a rear brake adjuster in the line to the rear brakes. Every thing worked fine in the driveway. I purchased a kit that is supposed to have the correct master cylinder. I did not change the porportioniong valve. (This is my first Mopar, I have done this same changeover on several Fords)
I trailered it to the paint shop (I do everything except paint). I tried to drive it home. everything was fine for about 1 mile.
The front brakes locked. I had to open the bleed valve on the wheels to get them to release. Any time I used the brakes they would re lock.   
Any Ideas on what I need to change??
Thanks Phill

[TylerCharger69]

Is the rod between the power booster and master cylinder adjusted properly?...That happened to me, and i needed to back off on the adjustment.  (Threaded rod)  It locked up everytime i would apply the brakes.  And....did you upgrade the master cylinder when you added the disc brake conversion???

[pmbly]

Yes, I did upgrade to a new master cyl. Thank you for the advise. I will try that tonight.  Phill

[pettybird]

proportioning valve sticking?  how are the rear brakes?  i've seen where the rear hose would swell, and on release would slide the shuttle valve closed on the fronts. 

[NMike]

the proportioning valve for drum brakes have a residual pressure valve. this only allows ~95% of the brake pressure to release from the wheel cylinders.

the pressure is needed to keep the cups in the cylinder expanded so the work and not leak.

disc brakes don't use this. the front outlet on the original proportioning valve is keeping slight pressure on the front brakes. they heat up and seize.