What Else?!?!?! (brakes)

[xtrememopars]

Replaced: Booster, Master cylinder , wheel cylinders , return springs , proportioning valve (wilwood) , brakes , Blew the lines , cleaned the T valve The one on the rear axle. after doing all that  my rear brakes are still slowly locking up and in dash brake light still won't turn off. I can't think of anything else to do... Im lost. any ideas guys? i'm working on 73 dodge challenger front disk, rear drums.

[Bullitt-]

The light staying on can only be caused by a ground being provided, normally two switches provide the ground, one is on the proportioning valve which you no longer have, the other is on the parking brake pedal and may need adjustment otherwise you may have a wire shorting to ground.

As to why your rear drums are slowly locking up I only have one suggestion, if the rubber brake hose has an internal rupture that allows fluid to build pressure between the inner & outer lining the brakes will be held on, unlikely but possible. I also seem to remember someone having problems caused by incorrect parking brake cables but I'm not sure they had the same symptom.
 I actually had this problem on a 240Z after replacing the pads & never figured it out other than the self adjusters were over adjusting, I just disconnected the adjuster.
  I have scanned the troubleshooting page from the '73 Service Manual for you. Good Luck

[brads70]

If your using the same wildwood adjustable p-valve I'm using , you don't hook up the dash brake light to this valve. It's set up as a alternate way to trip the brake lights in a hotrod for example.  Are the rear wheel cylinders slowly locking up and staying locked, or do they just lock before the fronts? If so use the truck wheel cylinders. I ran this set up before I switched to rear disc brakes and it worked great for me.

[Chryco Psycho]

is the pushrod too long onto the master cyl ?
If it is the fluid cannot return to the master , it is threaded & can be shortened , this is often a problem with a new master & or booster