67 GTX Power Drum Brakes Sticky Brake Pedal

[67GTX440]

I worked on my brakes right before my car went to paint. New power brake booster and master cylinder, rebuilt rears complete including wheel cylinders, shoes and drums, lines flushed and new brake fluid. The fronts looked fine. After getting the car back from 25 months in paint jail, the brakes work,but the pedal sticks. I have to pull it up with my toe to unset the brakes. I have lubed the pedal mechanism under the dash, but this did not seem to help. Where should I look next? Does this sound like a master cylinder problem or a booster problem. Would a vacuum leak cause this to happen? I am planning on changing the fronts to disks, but did not plan on the car coming out of the paint shop after 25 months with the brakes not functioning. What should be my plan of attack?
Again, the brakes stop the car, the pedal just does not release and return after it does.

Thanks!

Don

 

[Pops1967GTX]

Need to eliminate causes...sitting for that long period could of caused a few problems.. Sounds like a good time to check everything.
First Check brake pedal assembly ,disconnect master cylinder rod & see if pedal reacts normally.... try lubing the linkage pivots under the dash. if so move on to checking master cylinder & brake booster, check valve..What is the vacuum measurement ? ..The vacuum should be at least 18 inches.
Vacuum Brake Booster Testing and Diagnosis


Mopars & Missiles posted this test awhile ago......
This procedure will require the use of a hand operated vacuum pump with a vacuum gauge. If you do not own one it can often be rented or borrowed from most “big box” parts stores. (Note: 18”HG is the minimum engine vacuum at idle in gear to effectively operate a vacuum booster

1) Remove vacuum hose from check valve on booster. Place hose from vacuum pump onto
check valve and draw booster to 20” of vacuum.

2) Let booster sit with vacuum applied for 5 minutes. If vacuum does not stay steady at 20” it is
faulty and needs to be replaced. If vacuum does hold steady at 20” proceed to step 3.

3) With 20” of vacuum in booster depress brake pedal once and release it. The booster should
transfer some but not the entire vacuum in reserve. Depending on how hard the pedal is
depressed it is normal to see 5-10” of vacuum depleted from reserve. The most important
thing is to ensure the booster does transfer vacuum but does NOT transfer the entire vacuum
in its reserve. If vacuum remains at 20” OR goes to zero the booster is bad and will need to be
replaced. If vacuum transfer is within the above parameter proceed to step 4.

4) Once again draw booster down to 20” of vacuum. Go inside car and depress brake pedal and
hold down for 30 seconds. You should see the gauge drop slightly and then hold steady.
Vacuum should stay steady as long as you are holding the pedal down. If vacuum drops while
pedal is being held down the booster is faulty and will need to be replaced.

 

[67GTX440]

Need to eliminate causes...sitting for that long period could of caused a few problems.. Sounds like a good time to check everything.
First Check brake pedal assembly ,disconnect master cylinder rod & see if pedal reacts normally.... try lubing the linkage pivots under the dash. if so move on to checking master cylinder & brake booster, check valve..What is the vacuum measurement ? ..The vacuum should be at least 18 inches.
Vacuum Brake Booster Testing and Diagnosis


Mopars & Missiles posted this test awhile ago......
This procedure will require the use of a hand operated vacuum pump with a vacuum gauge. If you do not own one it can often be rented or borrowed from most “big box” parts stores. (Note: 18”HG is the minimum engine vacuum at idle in gear to effectively operate a vacuum booster

1) Remove vacuum hose from check valve on booster. Place hose from vacuum pump onto
check valve and draw booster to 20” of vacuum.

2) Let booster sit with vacuum applied for 5 minutes. If vacuum does not stay steady at 20” it is
faulty and needs to be replaced. If vacuum does hold steady at 20” proceed to step 3.

3) With 20” of vacuum in booster depress brake pedal once and release it. The booster should
transfer some but not the entire vacuum in reserve. Depending on how hard the pedal is
depressed it is normal to see 5-10” of vacuum depleted from reserve. The most important
thing is to ensure the booster does transfer vacuum but does NOT transfer the entire vacuum
in its reserve. If vacuum remains at 20” OR goes to zero the booster is bad and will need to be
replaced. If vacuum transfer is within the above parameter proceed to step 4.

4) Once again draw booster down to 20” of vacuum. Go inside car and depress brake pedal and
hold down for 30 seconds. You should see the gauge drop slightly and then hold steady.
Vacuum should stay steady as long as you are holding the pedal down. If vacuum drops while
pedal is being held down the booster is faulty and will need to be replaced.

Thanks! The vacuum pumps and self bleeder kits are pretty cheap, so I ordered one from Amazon. If the booster needs replaced, it seems like replacing both the booster and master cylinder are the way to go. Is there anywhere you can buy one like the original? The one that has been on 2 1/2 years and most likely has failed from sitting was from NAPA. I think it might be wise to do the brake lines also. Any suggestions for a source on that? The difference between the cost of steel verses stainless seems to be minimal. I may just order a disk brake kit and do everything all at once. I have been looking at the Wilwood with the 12.5 inch rotors. I think they will work with the standard power brake booster and master cylinder. Wilwood also makes them to fit the stock spindles. Not sure if a separate proportioning valve would be needed.

I have the dash on the dining room table right now making sure everything is pretty and installing a new under dash wiring harness. I sent some small parts off for chroming - radio bezel, radio knob bezels, A/C vents etc. I am hoping to have the guy come to install the new head liner next week. Progress is slow, but I am trying to do everything right.

Car would also not go into park when I got it back and had to be started in neutral. I found the plastic push button on the floor shifter was broken - threaded part was cracked. I already had a new one, but it took me all day to find it. I have so many parts stacked in the garage and around the house it is ridiculous.

 

[67GTX440]

While waiting for a vacuum gauge I ordered, I pulled the master cylinder from the booster and the rod in the booster did not appear to be attached to anything. I assume there is a return spring it is supposed to be attached to. Put on a new booster and the brakes seem to work fine Did not even have to bleed the lines since the master cylinder was never removed.

Did the booster replacement with the dash out, the AC ducts removed and most of the wiring harness disconnected as new one as going in with the dash. I have an all new respect for anyone who replaces a booster with all of this in place.

The 25 months in paint jail resulted in the booster malfunction, the fuel pump giving up and the car not shifting correctly due to a cracked push button on the console shifter. These all worked when the car was dropped off. Time takes its toll whether a car is driven on not. Maybe more when not.

I am still waiting for the hood scoops and one quarter panel extension to be repainted due to paint flaws.