Well if the inner seals were leaking you would not see it, it would just allow the fluid to flow where it shouldn't and defeat the purpose of a hydraulic system. It is hard to pinpoint because you dont lose 100% of your brakes but if it is as noticeable as you say then I would say you have a bad seal. With the money you have put into it, new MC and be done with it.

Ours is similar to this:

 

Thats pretty much what the shop explained to me

 

Nope. Rear ended. Don't think kid ever hit HIS brakes. I was sitting still, he was doing about 55mph. One of those time letting OFF my brakes saved me.

 

Before you replace the master cyclinder, try bleeding your brakes again to see if it helps.

To test the master cylcinder, with engine on, pump the brake pedal till its hard, keep and hold your foot on the pedal. If the brake pedal slowly comes to the floor, then your master cyclder seal is bad.

 

This is the exact symptom i have the pedal feels like its about to get hard and slowly goes to the floor

 

UPDATE:
Ok guys i am in serious need of help. I have now replaced my brake master cylinder, i did the bench bleed on the masyer cylinder and i bled all 4 brakes lines i kept bleeding till 20oz of fluid came out with no bubbles. I used the FSM order specified. And my brakes still feel the same!!
The only thing that changed is before i used to feel the pedal slowly want to go to the floor, that doesnt happen anymore.

Symptoms
Pedal feel is very soft
Car begins to brake after 50% pedal travel
Pedal CAN be pushed to floor with significant pressure.
The pedal NEVER gets firm while driving
I purchased the car with this problem in 02/2012

Parts replaced
6Th gen front calipers
6Th gen front hawk hps pads
6Th gen front slotted rotors
Brake master cylinder
Rear slotted rotors
Rear hawk hps pads

Brake gurus plz help, i have all these mods waiting to be installed but i dont even wanna work on the car since i got this problem.

 

Brake booster? Are you losing fluid level at all after topping off and pumping brakes repeatedly?

 

No fluid loss at all.

 

Check the brake booster if you haven't already... http://www.ehow.com/how_7507543_test...-boosters.html

Also, no issues with ABS?

 

^ this ^

 

Ok ill do this procedure. I never had an issue with ABS

 

Can anyone report on the durability of the HPS pads with just everyday normal driving and not racing? I think I got almost 40K miles out of the stock OEM pads. I don't want to get pads that I'll have to replace after only 20K miles.

 

If u got Good Even Pressure Out all corners of car and bleeding with proper sequence Id Replaced Calipers and inspect sliding pin grease up as needed.

Replace two Front Calipers and I Bet Problem Will Go Away. had similar problem on a Toyota Celica i gave up took to Brake Check they replaced damn near everything in was gonna give up till a tech suggested replacing front calipers. BAM had a pedal again after two years.


started with soggy pedal and got to a point where it traveled to the floor hardly stopping at all. had it professionally bled repeatly with no results swapped three master cyls out thinkin defective. i worked at brake check at time in did everything by steps in our computer.


Go To Brake Check they do free dignostics n will point out any odvious problems n quote you. i suggest replacing calipers cause seems you've replaced everything else properly.

its not the booster don't waste your time their if that goes bad brake will feel like ur stopping with car not running n no vaccum HARD PEDAL.


Good Luck.

 

My mechanic checked out my brake booster he said it was fine thats exactly what he said if it was bad it would be very hard. I DID replace both front calipers NEW. i have NOT replaced the rear calipers, im thinking about replacing them. My mechanic bled my brakes again yesterday for the 4th time and he says theres no air. So now he recommended changing the master cylinder again. So im gonna give that a try

 

Damn man you can't catch a break...

What brand calipers did you buy?

 

Undercar xpress from amazon. But like i said it felt this way before the brake upgrade, i just assumed the car needed brake pads and rotors.

 

Ya might as well replace rear as well. or get two vise grips n pinch rear lines and bleed n see if brakes stop without pedal droppin.

 

I heard about pinching the lines. Do i bleed first then pinch the line? Or just pinch it and press the brakes?

 

Pinch then bleed fronts only just to see if its one of the rear calipers causing soggy pedal.

 

Whats the best area to pinch the line?

 

About 4inchs away from where line connects to caliper. the rubber hose part.

 

Man this is a tough one! good luck with it. I was going to throw out there it could be a leaking piston if not the master cylinder. Would be hard to tell without breaking it down and taking the pads out.

But then the talk of all the junk in the rear line makes me wonder if the proportioning 4way valve or ABS distribution block is is clogged with junk.

 

Proportioning Valve!!! i was trying to remember the name so i could tell him!! if u pinch rear and same results id grab a new valve from junk yard! or remove urs n blow compressed air thru yours. should be mounted on fire wall and have 4 brake lines going into it maybe 5 i can't remember.

 

I explained to my mechanic if this proportioning valve could be a problem. He said if the valve was clogged you wouldnt be getting fluid out of the calipers so well when ur bleeding. I do get fluid out properly when bleeding so we omitted that.

I installed a 3rd master cylinder from the junk yard and it toally sucked ***** i couldnt get fluid out of the rear right and left front lines. So i reinstalled the 2nd MC and the fluid was pumping nicely.

I went to autozone and purchased two new calipers for the rear mad expensive total was $226 including the $60 core for both.

I bled everything in the proper order and guess what? It feels the same!

so i think i will leave this problem alone for a little while because im going insane chasing it . It brakes OK not good but just OK so as long as its not dangerous ill drive like this till i feel like battling with this again.
Run down of parts replaced in an attempt to fix a low brake pedal with less braking force than normal.

2 used OEM nabco master cylinders
Front
New 6th gen calipers
New 6th gen brakelabs slotted rotors
Hawk hps pads

Rear
New autozone 5.5th gen calipers
New 5.5 gen brakelabs slotted rotors
Hawk hps pads

To be continued..........

 

Small update just for future reference the other day my pedal began to drop straight to the floor. i noticed the right rear rotor getting rusty where the pad should contact the disc. bottom line the new autozone caliper was not working correctly got a free warranty exchange and rotor is now clean and pedal is back to a low pedal instead of a floored pedal.

I decided to try a brand new master cylinder because since everything else is new it just made sense to do that. Dont ever buy a Centric master cylinder i had to return it because it looked like a universal master cylinder the reservoir was all wrong and there was extra ports, looked nothing like the original. I bought a raybestos master cylinder and it was identical to the OEM.

after installing the raybestos master cylinder my pedal feels slightly higher and i feel slightly better braking force but my friends stock 2 yrs old pads and rotors feel wayy better. So i know theres still a problem.

I have been following this guide it seems great id like to share with everyone
http://db.tt/bzlmAgxH

I tested the brake lines with the line locks and those proved good (no change). Then i tested the master cylinder with plugs in the ports like it said and for the first time my pedal was to the top and hard as a rock indicating the master cylinder was good. After this test the document says a component between the master cylinder and the brake lines has failed. I think that the only component left is the abs module, anyone know how to bleed air out of this module or test this??

 

I know this is old, but bump!

I cannot drive my new swap at all, now. I have the same symptoms, but worse.
Did 6th gen BBK, bled the front and almost no braking power. I bled all four and nothing. I bled the MC and nothing. I replaced the MC and vacuum bled it all. It got worse! Power bled and still no change. ABS pos must be bad.

Yay for previous owners that have no business owning a car.

 

I was not satisfied with my brakes until I replaced the rear calipers. I also bled the brakes using speed bleeders and they cleared out all the air. Before, they seemed spongy, but bleeding did not help much. This is on an 03 I35.
I also did not have any real parking brakes until I replaced the calipers. How does your parking brakes work?

 

Rear calipers are in good shape and the brake works. I have never driven the car before I did all the work on it (motor was blown).

There is no pressure. The more it was bled the less pressure there was. There is virtually zero, now.

I had a local shop power bleed them and there's no change. There's just enough pressure to barely move the pistons.

Before my vacuum and power bleed the pedal would at least get hard with the engine off and there was a small amount of braking power at the very bottom. Now, even off, the pedal goes to the floor and BARELY returns. It's as bad as a clutch line full of air.

The booster clearly works and it has nothing to with piston travel in the MC (so the road is good) as you can pump fluid out strong all day from the beginning of the stroke. So, how does nothing happen when I test them? I don't have a gd clue.

I'm about to rip out the gd ABS module. Bled with battery off and on. Tested with abs fuse pulled. NADA

 

If you remove or loosen the 2 lines from the MC and connect a pressure gauge on both ports or plug one and connect the gauge to one of the two port and press the pedal and read the pressure gauge ....

 

Pressure isn't a problem as I just discovered.

I have never replaced or messed with a MC before. I don't know how far the rod is supposed to stick out or how it behaves with the booster. It moved perfectly with the pedal, though.

I assumed the rod was fairly fixed in position and shouldn't be adjusted. It seemed that it was good b/c it stuck out far enough to probably kiss the MC.

The rod was screwed most of the way in, so I backed it out until the MC was stuck out about 3/8" when hitting the rod. I pushed it in and hooked it all up.

Brakes work. There's some sponge at the top. Every maxima I've driven has had that to some degree, plus there's probaly a little air in there from removal. It really catches hard about half way and ABS kicks in.

Does this sound normal or should the rod not be backed that far out?

I don't give a ****. I need to get plates on it.