Brakes with No Prop Valve

[C20-67_N_MO]

I have power brakes with disc up front and drums in the rear.

However I do not have a Prop. valve installed and my brake pedal feel mushy at best.

Could this be the reason?

I can tell the PO ran new lines from the MC down to the frame rails, but why he toke out the Prop. valve is beyond me!

[MagmaJct]

I'm no expert in this area, I'm hoping others will chime in. It's my understanding that disc brakes require more force to function than drum brakes. This would cause the drums to lock up before the disc began to function. The proportioning valve balances this out. That is, without it you'd get equal PSI front and back, a prop valve would put more PSI to the discs and less to the drum.

Am I close?

[Longhorn Man]

MJ, you are right, the rear should be locking up plumbed like this.
The mushy pedal is most likely air in the system, or shoes out of adjustment. I would crawl under and follow the lines, there may be something in there you don't know about. An adjustable proportioning valve plumbed in the line to the rear brakes could be under there and you don't know it.

[cdowns]

if no proportioning valve is used and the rears lockup in a sudden stop??

you could b the first on your block to master the "bootleggers turn"

[C20-67_N_MO]

Nope.

There is no proporting valve in my brake system at all.

Brakes do not lock up at all.

Just don't seem like it has good pedal pressure, if that makes sense.