Brake Bleeding Problem --- NEED HELP

[Canuck]

In the process of converting my 64 Malibu from manual drum, brakes to power disk and have hit a problem.  CANNOT GET A HARD PEDAL,  IT DROPS TO THE FLOOR.  It does not pump up either.

The components:

The front disks/spindles are 70 GTO.  The Master Cylinder (1 1/8), Booster are 72 Chevelle spec'd for a power disc set up.  The rear cylinders are 15/16". All components are new, Wagner, the only rebuilt unit is the booster.  The combination valve is  a stock 72 Chevelle.  Basically the components that would be used in a 70-72 Chevelle with power disk brakes.  Pedal assembly is 64, with the push rod set in the power brake position.

The hard lines from the combo valve to the frame are new and feature about the only thing that doesn't look stock.  The three vibration loops in each line are vertical not horizontal due to lack of space.

The process:

Bench bled master cylinder and got a good clear stream from both ports with no air bubbles.  Installed in car and bled brakes and got clear streams for at least 10 pumps at each wheel.  Thought the master cylinder might be leaking internally so replaced it with another new one, no change.

The question:

What am I missing?  What can I try?    :?:  :?:

HELP guys and gals.

Canuck

[Arnold]

In the process of converting my 64 Malibu from manual drum, brakes to power disk and have hit a problem.  CANNOT GET A HARD PEDAL,  IT DROPS TO THE FLOOR.  It does not pump up either.

The components:

The front disks/spindles are 70 GTO.  The Master Cylinder (1 1/8), Booster are 72 Chevelle spec'd for a power disc set up.  The rear cylinders are 15/16". All components are new, Wagner, the only rebuilt unit is the booster.  The combination valve is  a stock 72 Chevelle.  Basically the components that would be used in a 70-72 Chevelle with power disk brakes.  Pedal assembly is 64, with the push rod set in the power brake position.

The hard lines from the combo valve to the frame are new and feature about the only thing that doesn't look stock.  The three vibration loops in each line are vertical not horizontal due to lack of space.

The process:

Bench bled master cylinder and got a good clear stream from both ports with no air bubbles.  Installed in car and bled brakes and got clear streams for at least 10 pumps at each wheel.  Thought the master cylinder might be leaking internally so replaced it with another new one, no change.

The question:

What am I missing?  What can I try?    :?:  :?:

HELP guys and gals.

Canuck

  Get a couple of short pieces of new brake line..and some fittings that will fit the m/cyl..Cut them short and with the fitting on..hammer the end...or vice grip them so that they seal.This is easy..
   Bleed the m/cyl.
   Plug it with the above fittings.
   Now you have a high,hard pedal..or bad m/cycl. or p.rod waaaay out.
   Take the plug out of the m.cyl port for the rear lines.Put the line on.Take the lines off the whl cyls.Get a couple joiners.Plug them.Bleed the rear lines.You are back again to a firm,high pedal.
   Adjust the rear brakes.Make sure the drum/shoes are the right size..the backing plate is not toast and the shoes aren't hanging up/The adjuster/parking linkage etc are there and good..and adjusted.
   Bleed the rear wheel cyls.
   You now should have a hard/high  pedal.

    Same for the front..bleed the lines..make sure the calipers are the right ones..not sticking/stuck.Good rotors/pads..bleed the calipers.

   I am sorry if this sounds simplistic..but this is what I do NOW..as I can work my way back until I find the problem..getting a firm/hard pedal each step of the way.I find that skipping these procedures after I have had a tough one..trying to re-bleed etc.,etc., only leads to frustration and more mistakes.I adopted this procedure after many,many years..and times  of wrong parts/defective new parts..mistakes..simply an un-ending amount of frustration/wasted time.This is very,very simple and flat out works.
  I have a pretty good assortment now of plugs etc.,

  Good luck..

[Pep]

To simplify things...just use vise grips on the rear hose....pedal ok or no?
if not, use vise grips on both front hoses....pedal ok or no?. Once that's narrowed down you can focus on the front or rear...I suspect the pads are not in constant contact with the disks. There will be a gap when you take the pressure off

[48ford]

This may or may not be your problem,but one time I had the calipers on the wrong sides,fliped them side to side and that was it.
As others stated plug the master,see if it holds and start working one spot at a time.
Good luck
Russ&irene

[C9]

Caliper bleeder screws at the high point so the air bubbles can go up and escape?

[48ford]

What did you find out?
Russ

[Canuck]

You nailed it Russ.  A brain fart on my part, old age creeping up on me I guess.

This was preceeded with picking the wrong booster, a 64 instead of a later model.  Then a defective NEW master cylinder.  Then a rear wheel cylinder bleeder valve leaking (old cylinder) and needing new brake shoes on the back.

Running fine now, just cleaning the winter dust off it a getting ready to go to BTTFs.

Jim

[Canuck]

Just so you know what you have helped get back on the road.

Previously with quick ratio power steering, HD sway bars front and rear, 406 / 700R4.  Now with power disk brakes.  A nice driver that is now even better.

Thanks guys

[bucketmouth]

Just a word of warning, if anyone is gonna use vice grips on the brake hoses wrap some cardboard or plastic around the hose first as the jaws could damage the rubber and burst the hose under pressure.
Also only  tighten the vice grips enough to crimp the hose or you will definately damage the hose.