front disc brakes won't release

[damaged]

Stats... front 60 with new rotors, new calipers, new master cylinder, proportioning valve from 1978 ford pickup pic n pull.
question
when I apply the brakes the calipers move to lock the rotors but they don't release. It seems the system is not allowing the fluid to return to the master cylinder when the brake pedel is released. would my salvaged proportioning valve have anything to do with this.
Has anyone run into this before.
any ideas are appreciated
thanks
John Sullivan

[kwspony]

Re: front disc brakes won't release

was the master cylinder for a disc or drum setup?

[71BRONCO71]

Re: front disc brakes won't release

If it was a drum/drum you will need to pull out the ball and spring from the master cylinder for the front fluid bowl. Drum brakes need 15psi in the lines at all times, Disc need 0psi.

The young grasshoppa has learned well....

[damaged]

Re: front disc brakes won't release

The master cylinder was changed to a disc drum setup. I'm not sure what it was from, I got it for free from a friend. Could this be a rod adjustment problem between the brake booster and the master cylinder? Additionally the proportioning valve is from a 1978 for pickup with disc/drum.
thanks everyone
John Sullivan

[Rockbronco67]

Re: front disc brakes won't release

Do you have your lines crossed? if not try a different valve

[damaged]

Re: front disc brakes won't release

what do you mean by "Crossed" front to rear or side to side? The valve has three outputs so I just assumed the end with two where for the fronts. Is there a left and right output? the pictures are of the proportioning valve. There was an electrical connection on the top of the valve. I do not know what purpose that served.
thanks
John Sullivan

[Rockbronco67]

Re: front disc brakes won't release

Just make sure your front disc line is not on the drum side of the MC. I think it is the valve because it is not releasing the pressure. Try to bypass the valve and see if it works. Then if it still does it then it is probably your MC.

[71BRONCO71]

Re: front disc brakes won't release

the larger bowl is the front.
still sounding like a drum/drum MC

[damaged]

Re: front disc brakes won't release

Sometimes it's a wonder how I get myself dressed in the morning!! You know the adjustable rod that comes out of the brake booster. Yeah the adjustable one!! When it's not adjusted right (the rods too long) it preloads the brake master cylinder or in other words it applying the brakes.
So I adjusted the rod and now it works fine.

THANKS everyone
John Sullivan

[71BRONCO71]

Re: front disc brakes won't release

SCORE! i hate it when i do stuff like that.