Brakes.......Or Lack There Of

Well i decided to try adjusting up my rears. i got them adjusted up properly and went for a test drive. the pedal is low and soft. i can push he pedal all the way to the floor and not one of the 4 wheels even thinks of locking up.

New parts:

• Master Cylinder
• Vac Pump
• Front callipers
• front pads
• front rotors
• rear shoes
• new front rubber hoses
• all internal components on rears

I have deleted the RABS vavle.

The only thing that i have not replaced is the brake booster that mounts to the firewall.


I have bleed over a gallon of brake fluid threw the entire system. new brake fluid.


The only logical thing left would be a bad brake booster. when i hit the brakes i get a whooshing sound from the location of the booster. i don't know if that noise is normal or not.


Can anybody say hydro boost?
i think it will happen sooner rather than later. the brakes are just not safe anymore. if somebody pulls out in front of me i might as well not even make the effort to stop that is how poor the brakeing performance is.

I have read threw the h-boost tech article. i would need the hydro booster, h-boost p-steering resivior, two lines that go to the booster and booster to steering box. am i missing anything?

Rock auto has reman A1-Cardone booster for $173.
How big a risk do i run getting a bad booster from a junk yard?


Thanks

Don't get a cardone booster. Sounds like you should check your vacuum hoses and the connection going into the booster.

i have good vac and no vac leaks. Wouldn't lack of vac give a hard pedal? the pedal is so soft you can almost look at it and it would go to the floor.

What is wrong with cadone?

'94IDITurbo7.3 said:

i have good vac and no vac leaks. Wouldn't lack of vac give a hard pedal? the pedal is so soft you can almost look at it and it would go to the floor.

What is wrong with cadone?

Click to expand...

Nothing wrong with cardone, I got a booster of theirs and it was crap. I like their other parts.

If you don't think vacuum is a problem than why do you think your booster is bad?

Please explain your process of bleeding brakes.

I say booster b/c it is the only thing left that could be bad. is there things inside the booster that can fail?

Bleeding:
i like the two person method. one inside pumps the pedal, the other under the vehicle craking the bleeders.

i went right rear, left rear, right front, left front.

I did bench bleed the MC as well before i installed it.

is there weaping behind the MC down the front of the booster? Could the new MC be bad and fluid leaking past the seals thus preventing good solid brake action?

Can you put the OLD MC on...and test for chits n giggles? That is if it worked at all. Ifso that is one way to eliminate one sorce of potential problem.

Going to hydro will not solve the issue. The stock Vaccuum setup should be working correctly prior to your switch. The hydro is just a replacement booster nothing directly related to the actual braking of or operation of the brakes...hope I am making sense here.

Is there a residual pressure valve that was left out or put in? You said you removed the RABS...maybe it's something to consider putting in to diagnose issues?


JM2CW

one more thing that comes to my mind is the pushrod in the booster adjustable and is it adjusted properly. the master has to be removed for inspection and adjustment.

riotwarrior said:

is there weaping behind the MC down the front of the booster? Could the new MC be bad and fluid leaking past the seals thus preventing good solid brake action?

Can you put the OLD MC on...and test for chits n giggles? That is if it worked at all. Ifso that is one way to eliminate one sorce of potential problem.

Going to hydro will not solve the issue. The stock Vaccuum setup should be working correctly prior to your switch. The hydro is just a replacement booster nothing directly related to the actual braking of or operation of the brakes...hope I am making sense here.

Is there a residual pressure valve that was left out or put in? You said you removed the RABS...maybe it's something to consider putting in to diagnose issues?


JM2CW

Click to expand...

no weaping from behind the MC.
the old MC is gone.
The only pressure valve on my system is the pressure differential valve that screws into the back port on the MC.
I could put the rabs back on but i would have to go to the scrap yard to find a fitting for it b/c somebody else had been into it before i got the truck and messed up the threads.

Towcat: i made a gauge out of steel for the booster pushrod length and i set it but i will check it again to verify.


thanks for the replys

The vacuum booster has a diaphragm and big spring in it, the spring being defeated by vacuum from the pump and helping the brake pedal pressure. If the diaphragm is torn, you will not feel the vacuum boost. If there is no vacuum and the diaphragm is good, you will have hard pedal pressure because you are pushing against the diaphragm and spring, plus the pressurized area inside the body. You probably have a bad booster. And no, it is not normal to hear a rushing sound when the brakes are applied, that is the sound of air rushing by the torn diaphragm.

Where did you get your M/C?

Whoosh from the booster is a bad sign.

This might sound crazy, but is it possible that you have a pinhole rusted in a brake line somewhere and you haven't noticed the leak yet?

In college I had the brake line on my 1969 Cadillac ambulance rust out half way between the front and the back, and it took me about 6 months to figure out where the fluid was going! I had similar low-pedal issues.

If you take off the master cylinder cover and have somebody lightly depress the brake pedal (maybe a 1/4 of the way down, slowly), do you see any bubbles coming up in the reservoir? I have bench-bled and vehicle-bled a lot of master cylinders, and no kidding I think I have done it for almost an hour before I finally got all of the air out in some cases.

Diesel_brad said:

Where did you get your M/C?

Click to expand...

car quest.
i don't know what brand. i did ask them if they offered a brand new mc rather than a reman and they did so i got the new one. but i guess there is a possibility that the new one could be bad too.

Knuckledragger said:

The vacuum booster has a diaphragm and big spring in it, the spring being defeated by vacuum from the pump and helping the brake pedal pressure. If the diaphragm is torn, you will not feel the vacuum boost. If there is no vacuum and the diaphragm is good, you will have hard pedal pressure because you are pushing against the diaphragm and spring, plus the pressurized area inside the body. You probably have a bad booster. And no, it is not normal to hear a rushing sound when the brakes are applied, that is the sound of air rushing by the torn diaphragm.

Click to expand...

to make sure i understand, if the diaphragm is torn inside the booster on the firewall then the pedal will be soft.
If the brake booster is good and the vac pump is bad i would have a very hard pedal with no power assist.

I will see if i can get a sound clip of the whooshing noise tomorrow.

So if my booster on the firewall is all that is bad then would h-boost solve my problems and give me the benefits of h-boost?

tomorrow of friday i will hook my vac gauge back up and see what is what there.

redmondjp said:

This might sound crazy, but is it possible that you have a pinhole rusted in a brake line somewhere and you haven't noticed the leak yet?

In college I had the brake line on my 1969 Cadillac ambulance rust out half way between the front and the back, and it took me about 6 months to figure out where the fluid was going! I had similar low-pedal issues.

If you take off the master cylinder cover and have somebody lightly depress the brake pedal (maybe a 1/4 of the way down, slowly), do you see any bubbles coming up in the reservoir? I have bench-bled and vehicle-bled a lot of master cylinders, and no kidding I think I have done it for almost an hour before I finally got all of the air out in some cases.

Click to expand...

i have not noticed any loss of fluid.

i don't see any bubbles in the mc.