Not the one to the pedal, but the one between the booster and the master.

He had this problem before he changed the MC. Gotta be air in the system, somewhere.

No brakes at all unless I plug the vacuum line. Replaced the M/C again and still no brakes.

Any chance a bad wheel cylinder would cause this?

I replaced my booster a couple of years ago. It was one of the nastiest jobs I've had to do on the bird, as the 4 nuts holding the bracket to the firewall were totally seized. Nothing would free them up so I had to cut the old bracket/booster off and install 4 new bolts through the firewall.

Good luck!

Yes! Happened to me the weekend before last and had both front cylinders replaced. Can you see any brake fluid leaks onto the inside of the tires?

Yes but, there would be quite a bit of fluid accumulating in the drum.

Not if thier sucking in air one way...and not much fluid leaking out?
Kinda like water finding its own level sort of thing...???

...but its gotta be making room for the air by losing fluid...

ANY sign of fluid getting past the wheel cylinder seals is unaceptable. Not to mention unsafe. If you see any sign of leakage it is time to replace the cylinder. If it were mine I would do all of them, if they are near the same age.

Did i miss a post?
69verts correct. Absolutly no fluid leak!

Don't know if you missed a post or not. Just seems that if air is entering the system, then fluid should also be leaking out. Just exploring all possibilities...to get Jon back on the road.

Agreed.

I have scrounged up all new hardware (cylinders, pads, springs and related hardware) and have an appointment tomorrow with a local Brake specialist. Will let you all know how this goes.

There could be a signifigant problem with your game plan. These system are so obsolete that you will be lucky to find someone who has a remote clue how to do these kind of brakes. They are simple, but you have to understand them. It's kinda like removing the window crank clip, an easy process if you understand what your are doing.

Hey John,

Are you one of the copter pilots in your flicks?

Like your youTube flicks! My buddy had a 428 in his blue 68 FB with 411's. Man that puppy would go!

Good luck with your brakes ... your going to need em!

Gus, I am the tall dark-haired guy in the videos...the one that thinks he's in charge!

Merv, you are right, but the Brake guy owns a 1968 Camaro and did my alignment last year. All he does is brakes and alignment. Otherwise I would not take the bird to him.

He fixed the brakes today, in about 65 minutes! Replaced the two front wheel cylinders, professionally bled the system, and adjusted all four brake assemblies. I'm sure he did a few other things. Brakes are stronger than ever now, plus he properly adjusted my parking brake, which has never been 100 percent right.

Thanks for all the help gang; I learned alot on this subject.

Cool, glad you got it sorted out!

Bout darn time!

Yuppers, looks like it was a combo of things. Leaking M/C with front leaking wheel cylinders and possibly a booster, but good to change regardless. Gotta always remember to pull back the outer boot on the wheel cylinders to check for leaks when your looking at them.

bump,bringing this thread back up as i started my bird the other day for the first time this year and the pedal went to the floor with the same vacuum sound John had.I took the booster off and am going to order a new one (3 yrs old) but after reading this i'm wondering if i need a master cylinder too! (don't know how old it is)

I just went thru the same issue and it was the booster.

some more info -4 wheel drum,wheel cylinders are dry.master cylinder is full,don't see any leaks.so what you think replace booster first and then if no change replace MC or replace them both ?

most likely master cylinder internal seals.

I ordered a new booster today so i will try that first,then if need be the MC next.

UPDATE- Installed new booster today and all is fine now.