Booster Issue?

[srgould41]

I assume you have drums up front too. Did you adjust those also? By chance did you make sure your 10lb residual valves were in the master you installed? If not then that could mimic the same thing you are feeling. Pumping the pedal makes it firm and it stay firm, correct?

 

[Boaf 32]

I assume you have drums up front too. Did you adjust those also? By chance did you make sure your 10lb residual valves were in the master you installed? If not then that could mimic the same thing you are feeling. Pumping the pedal makes it firm and it stay firm, correct?

SRGold41 Yes, Drums up front and adjusted in the same way as the rears (removed the drum, set the Cylinders to the same adjustment, put Drums back on adjusted wheels to not spin, and then backed off 2 clicks for a firm drag on the tire).

I have not heard of the "10LB residual valves. What is it and what does it do?

Bottom line, I replaced the Master Cylinder and still have the same pedal response as before. Leads me to believe it is NOT the master cylinder, but I can be wrong....

I do hear a "bellows" type noise when stepping on the brake pedal

 

[Trollhole]

It sounds to me that your booster is bad. When you tested your booster did it hold a vacuum?

 

[srgould41]

Would a bad booster do this with the engine off? Boaf said his brake pedal sinks to the floor with the engine off.

It sounds to me that your booster is bad. When you tested your booster did it hold a vacuum?

 

[Boaf 32]

Testing it later today. However, when I Pump up the brakes, keep my foot on the pedal then start the LC, the vacuum works and pulls the pedal down. Here is a post earlier in the thread:


Replaced all Pads on 1972 (10/71) LC Bled Master Cylinder, Front and Rear brakes (roughly 2 pints) and adjusted the shoes to a nice rub. I step on the brake when driving and it's firm at first, then fades to the Brake travel stop point. When stepping on the brake, I hear a below type noise; not a hiss, but a moan type noise.

1. Took the Vacuum hose off at the Manifold, tried to blow into the booster and could not (is that right?)
2. took the hose off at the booster end and of course was easily able to blow through into the manifold.

Response from Shawnfj40:


1 = yes that's right.
2 = Yes that's right too.
3 = Sounds like your booster is fine. You either have air still in the system or more likely your Master is shot.

Pump up your brakes with the engine off, while holding the peddle down start the engine. If the pedal pulls down more, the booster is working.


SRGould41 is right, pedal sinks to the floor and stop point with the engine off...

Is there some kind of Compression cylinder in the Pin that pushes the master cylinder???

 

[Trollhole]

One thing at a time.

How old are your rubber brake lines?

 

[Boaf 32]

Ordered a new set today. Methodical approach, yes...

When I have someone step on the brake, I hear that moaning sound, which I thought could be a line (even though I see no leaks or expansion of the rubber lines. Once replaced I can let you know. They look pretty good but the car sat for a year outside I believe (based on the inspection sticker)

The MC was a bit cruddly looking at the connectors, so was comfortable spending the 35 bucks for it.

Any other thoughts Trollhole?

 

[handcannon]

It's a fair question, you never know if the person is experienced or not. Yes, been "Braking" for 30+ years now. I bled the fronts, the rears and the master trough a bleeder valve on the side of the master with the assistance of a pedal pusher partner.

Now, I press the brake, it travels to the stop point and the red light indicator comes on. Guess that is correct because there is a brake problem somewhere.

I've been through 3 full cups of brake fluid in the front and the rear chambers. There has to be some air somewhere, and I see no leaks, no fluid anywhere. New brake cylinders in the rear.

Thoughts???

I didn't go back and re-read everything, so I may have missed your answer to my question. But, are your rear cylinders OEM, or aftermarket? What I'm going to describe may not be what you are dealing with, but then again it may.

I've never experienced this personally, so I may have my facts a bit out of place. But, I've read of others having big problems with bleeding aftermarket cylinders. For some reason getting all the air out is hard to do. What they eventually did was to pull one rubber cap off and carefully tip the piston and had more air come out. I don't know if this is your problem, but it would not hurt to check just to rule out this area.

Don

 

[Boaf 32]

I didn't go back and re-read everything, so I may have missed your answer to my question. But, are your rear cylinders OEM, or aftermarket? What I'm going to describe may not be what you are dealing with, but then again it may.

I've never experienced this personally, so I may have my facts a bit out of place. But, I've read of others having big problems with bleeding aftermarket cylinders. For some reason getting all the air out is hard to do. What they eventually did was to pull one rubber cap off and carefully tip the piston and had more air come out. I don't know if this is your problem, but it would not hurt to check just to rule out this area.

Don

Thanks for the "Tipping" approach. Yes, it was discussed earlier. As Trollhole indicated, I will be replacing the Rubber brake hoses first, and go from there. Thanks, let you know how it goes.

Boaf

 

[handcannon]

I am following your thread since I am interested in the final solution. I ended up going with four wheel disc, but the knowledge of what your final solution ends up being is important to me.

Don

 

[Boaf 32]

OK, will document.

Boaf

 

[Trollhole]

The MC was a bit cruddly looking at the connectors, so was comfortable spending the 35 bucks for it.

Any other thoughts Trollhole?

You paid 35$ for a new master cylinder?

 

[Boaf 32]

You paid 35$ for a new master cylinder?

$35 + a $30 re-core from Rock Auto (no reservoir).

 

[Boaf 32]

One thing at a time.

How old are your rubber brake lines?

Trollhole, Had my wife step on the brakes while I watched and felt the rubber brake lines front and rear. I saw and felt nothing unusual, Crap!. Like I said, new lines are on the way, but not sure that will solve the problem.

The only think I hear is a Bellows noise that comes from the Brake Booster when stepping on the brake. I am pretty sure all the air is out of the system.

The booster seems to be working correctly, gives me support when the engines on and the brake is pressed. Will get back to you after the lines are installed and bled. Thanks for your help.

Boaf

 

[GRM]

What brake shoes are you running? I've glazed shoes within 10 miles of install and had the same issue your speaking of.

 

[JohnnyC]

Still not adjusted right or air at the cylinders

Had the cylinders ever been changed with aftermarket?

 

[JohnnyC]

cylinder issues with difficulty removing air...

Threads:
Disc/Drum Double Pump Pedal Finally Solved


With pics (that helps people learn lol):
Still no brakes!

 

[Boaf 32]

Gentlemen,

A question on the brake system for my 72 LC with all drum brakes. Are the front and rear brakes split into two (2) separate systems? Meaning, if the rear's had a catastrophic failure and lost all fluid, would the front's still work?

Thanks. Will disassemble the rear wheel cylinders to ensure no air in them AFTER replacing the rubber brake lines.

Boaf

 

[Racer65]

Gentlemen,

A question on the brake system for my 72 LC with all drum brakes. Are the front and rear brakes split into two (2) separate systems? Meaning, if the rear's had a catastrophic failure and lost all fluid, would the front's still work?

Thanks. Will disassemble the rear wheel cylinders to ensure no air in them AFTER replacing the rubber brake lines.

Boaf

Yes, front and rear are separate circuits.

 

[Boaf 32]

Thanks Racer, so if there is air in the rear circuit, that should not, in theory, effect the front circuit, correct?