okay so my rear brakes are brand new and my front's are fairly new as well, the brakes have also been bleed recently. i just don't have the stopping power that i used to, i mean before i could slowly apply the brakes and then go hard before i'm stopped and lock em up, but today i was going 40 and slammed on them as hard as i could and they didn't lock up one but. the pedal also goes to the floor when i step on it to stop. could this be a master cylinder or brake booster problem?

 

goes to the floor, means air in the system. The common one is air in the MC and bench bleeding is necessary, plenty of info on that if you do a search.

 

air in the brakes give you a real squishy feel, this is pretty much a hard petal and i just can't get the car to stop like it should.

 

If it was a "hard pedal" then it wouldn't go to the floor. Bleed the system. If that doesn't fix it, take the MC off and bench bleed it. Then re-bleed the system.

 

Could be a number of things. If the problem started immediately after the rear brakes were replaced, suspect something in the rear brakes themselves. If the initial adjustment wasn't done, that could account for a low pedal and lack of stopping power. It's also possible that a wheel cylinder was damaged and is now leaking, or that something wasn't put back together properly.

If OTOH they were fine one minute and then suddenly bad the next, that is generally indicative of a hard failure in the hydraulic system. The master cylinder is the most common culprit with 'pedal to the floor' problems, but the entire system will need to be looked at to determine the exact cause of the problem.

As for bench bleeding the master cyl.....this generally isn't necessary unless (a) a new master is being installed, or (b) the master has run dry.

hth.

-B

 

Have you ever replaced any of the rubber brake hoses yet? Check those too, make sure that none of them are ready to explode. Over time, they deteriorate, crack, and either collapse or explode; I'm on my 3rd set.

 

yea i'm figuring that its either a seal in the master or my brake lines = poop. my front brakes are still the stock rotors with some hard *** cheapy ceramics so thats not helping but the rear brakes are adjusted fine with new self adjusters. when i replace the fronts with some plain brembo's and hawk pads i'll prolly find a reman'd MC and get some new stainless steel braided lines. and i know the booster works fine cuz it drops the pedal 1" when you start it.

 

I just read your rear brakes were new so and the adjustment thing makes perfect sense. If the mechanic didn't adjust them right there would be too much clearance between the shoe and the drum requiring too much pedal effort. As long as he didn't replace the wheel cylinders in the back there should be absolutley no reason for air in the system. You can take off the wheel and drum and adjust the star adjuster to expand the assembly so that the shoes just barely touch when you put the drum on. Or you could drive in reverse and come to a complete stop a billion times.

 

after the tech failed to replace the rusted and faulty self adjusters he had do replace both of em for free and i paid at cost for the two adjusters. and then when i got home i made sure they felt adjusted and then did some reverse stops also. i'm really beliveing its the MC and thats going to get replaced asap along with some new lines. thankx for the help guys

 

Id do a gravity bleed. Air is hard to get out of the system sometimes. I like the gravity bleed as its nice and slow and works every time.

It works just how it sounds. Crack the bleeders open and just let it drip out. You can do both rears and both fronts at the same time. All you gotta do is leave the master cylinder cap off and make sure it stays full. Every 3 mins check it and top it of. Its seams slow, but walk away for more then 3 mins and it will run the system dry.

Great way to bleed though. Also flushes out the old fluid better.
[Bake fluid is cheap too.]
You can set a plastic cup on an angle to catch the drips if your worried about pollution.

 

sounds good, i'll try that

 

Did that help any???

 

i have to actually buy and install the stuff first, i found out recently that i have severe back problems at my old age of 18 and i got a bunch of parts that are waiting to be put on. i got new springs/shocks/struts as well as rotors. i'm doing the brake lines and MC all at once. but thats only once i can get my back in check. but i'll definitely try that when i do attempt, sorry i couldn't get to it sooner but i'll let you know as soon as i do.