Well, just changed the master today and it's still doing it.[img]smileys/smiley5.gif[/img] So you guys say it's not the brake booster?

 

From what you described, the pedal goes almost to the floor and engages in the last 10% of travel. That would not be a booster. As SW2CAM stated earlier in this post, a bad booster would make the pedal very hard to push down, let alone, to the floor. A booster is operated off vacuum from the engine. If it looses vacuum, it will no longer assist in depression of pedal. Disconnect the vacume hose from the booster and try to depress the brake pedal and you will see what we are talking about.


However, a thought would be to check linkage between pedal and booster and/or to see if there is a push rod missing between booster and master cylinder plunger. If you put the new master in yourself, you should have bench bled it prior to installation. If you have not done this yet, that would give reason to why the brakes are still soft. To perform this you will need a bench bleeding kit. If you are not sure how to do thisthentake the car to a professional brake specialist to have the brakes bled. Not a dealer. A dealer is more expensive and less apt to finding problems. They like it when you have to come in three or four times to fix the same problem. No offense to any dealer mechanics, just the propaganda. And a last note, to review the problem;


1. Brakes going to floor barely engaging


2. No fluid evident anywhere


3. Brakes have good pads and shoes


4. Replaced Master cylinder


5. No change


The only logical explanation is that either there is still air in the system , or there is a push rod missing between booster and master.


Iown and run a small mechanic shop for the local people in my area and have had several cars that required several bleedings before all air is out of lines, even with a power bleeder.








Edited by: answerman

 

I had the master put in by a mechanic. He did bench bleed it but says he "didn't really like they way it bled" so you're doing it again Monday.


Ya...he did say it isn't the booster either. Good cause I don't want to buy it. [img]smileys/smiley1.gif[/img]We'll see how it goes Monday.

 

Oops, sorry Plasticmobile. I didn't check the user name before reply. Thought you were Alex-t. Either way, my post should help with both cases, and good luck with yours. I am sure you still have air in the system and just needs to be worked out. Sometimes driving the car for a couple days and having brakes re bled helps.

 

Well, we've found a consistent unusual thing with the brakes. The pedal goes almost to floor and lack of brakes happens ALWAYS when: I back up,go forward, then push the brakes to stop. Even the brakes are ok when I brake to stop from continuing to reverse. It does still happen occasionally while driving or going forward.

 

I don't want to steer you in the wrong direction if you have not had the master and all four wheel calipers/cylinders bled at least four times, but just a couple questions;


Have you had the brake padsreplaced recently? Does your car have drum brakes in rear? If these are both the case, it is possible that there may be an adjuster out of adjustment on the rear brakes. If too loose, your brakes may grab very well when reversing, but will allow excessive travel when going forward. Adjusting rear drum brakes can be performed by driving in reverse a shortdistanceand applying the brakes in short bursts, slightly more aggressive than normal braking. Repeat this a couple times. If there is still no difference then I am at a loss unless I am able to take a look at it in person. Hope this helps.

 

The brakes have been bled 3 times and master when it ws installed. I'm wondering how air could get in if nothing was done to them recently and this wasn't happening until a couple of months ago.


Pad's have not been replaced but rotors have. They were done this past summer. Drums in rear. Rear brakes have been adjusted twice but not with the method u described.

 

I would definitely check the shoes on rear for uneven wear or for looseness in assembly prior to the adjustment I described. Also make sure that it is possible for your particular car to have the brakes adjusted that way. As far as the air in the system, when you are braking in normal conditions, the fluid has contact from
the master to the calipers/cylinders by means of hydraulics. If air has been introduced to the system by a faulty master or other
means, the air will create a pocket and absorb the pressure from the
fluid, thus creating soft and mushy brakes. If there is air trapped in a bend or fitting, the fluid will travel past the air and not push it out when bleeding.

Now considering that it is intermittent I would check the components of the rear brakes first. Springs, Adjusters, condition of drums, etc. If the pads or shoes are worn, the fluid has to travel farther to get the pads/shoes to make contact with the stopping surface of rotors and drums, also creating a mushy brake.

 

Well the rear brakes have already been checked and adjusters have been taken out and cleaned and shoes are ok.


One thing that really hasn't been checked in depth are the fron pads, rotors and calipers. This is our next step. I guess they were bypassed thinking that it was the master right away. It goes in again tomorrow.[img]smileys/smiley12.gif[/img]

 

You see.......pays to look at the small and cheaper stuff before going any farther. [img]smileys/smiley12.gif[/img][img]smileys/smiley12.gif[/img]Found the problem today. Was the front pads!! Pretty much fell out in pieces when the caliper was taken out. Never thought to look at those til now. The symptoms that it was having pointed to master but after realizing that it only happened after reversing first, that there might be something wrong with the front calipers/pads.


Happy now but I just wish that I/we could have found this in the beginning before spending around $200, not including the new pads on now. [img]smileys/smiley8.gif[/img][img]smileys/smiley5.gif[/img]


Oh and sorry AlexT for taking over your thread.Edited by: Plasticmobile