Disc brakes locked

-
Sorry 30 years as a certified mechanic and working in shops my life I have seen the valves cause this. They can hold enough to stop a rotor from turning by hand but you could put it on the ground and drive it until it ignites the pads from dragging.

You may be right but it's not from the TYPE of device or how it works. This is caused by things like corrosion, rust, and other malfeasance plugging up the switch / piston mechanism. This is a piston operated switch. It is not a valve.

A good read...........

http://www.mymopar.com/downloads/mtsc/232.pdf

n a movie

[ame="http://www.youtube.com/watch?v=14JZQ3W6qYg"]MTSC - 1967, Volume 67-3 Dual Hydraulic Brake System - YouTube[/ame]
 
I loosened brake lines at master cyl . Can just barley turn rotors VERY tight but not locked.
 
^^^^^^^This x2!

For the record, even the residual valves in the master (if it even still has them) only hold about ten psi. It's to keep the cups in the wheel cylinder expanded and keep air from being sucked in. At best it will only cause a light drag on a disc brake caliper of the size commonly used on our cars. It won't compound with every step of the pedal, it will only hold ten psi.

Proportioning valves are used because it requires more pressure to work a disc brake caliper than a drum brake wheel cylinder. The valve holds off pressure to the rear brakes for equal braking performance. They aren't needed in an all drum brake system.
 
I loosened brake lines at master cyl . Can just barley turn rotors VERY tight but not locked.

If you crack a bleeder screw now without stepping on the pedal, do you still have pressurized fluid?
 
You may be right but it's not from the TYPE of device or how it works. This is caused by things like corrosion, rust, and other malfeasance plugging up the switch / piston mechanism. This is a piston operated switch. It is not a valve.

A good read...........

http://www.mymopar.com/downloads/mtsc/232.pdf

n a movie

MTSC - 1967, Volume 67-3 Dual Hydraulic Brake System - YouTube


The residual valves I speak of hold 5 to 10 psi and dont have a switch piston mechanism in the master cylinder to operate them so I did not bother watching your video.
 
Watch this all the way through.....


[ame]http://youtu.be/qfOvglchjeo[/ame]
 
Have you checked to see if the caliper pistons are frozen?
 
-
Back
Top