i'm gonna die if i don't fix this

[JDM onlyy]

alright, when i got my car, it had a braking problem. like when u hold ur foot on the brakes it feels mushy and then they fall to the ground. the guy i bought it from changed the master cylinder but it didn't help. and i went to get another master cylinder from him from a car he was parting. worked for a lil bit but now its back to the same thing. what do you think can be the problem?

[Humphrizzle]

bleed the brakes.

[JDM onlyy]

bleed the brakes.

done it, fixed it for like a 2 weeks and went back to the same thing again

[ksniperfox]

hole in brake line somewhere? leaking piston boot?

[Humphrizzle]

prop valve?

[JDM onlyy]

where's the prop valve? and how much is that?

I was thinking maybe a leaking piston boot because I noticed if I step on the brakes hard that it jerks to the left like that side's brake clamped down but the other side didn't clamp as hard.

[mocha latte cupcake]

agreed. check for leaks in your system. there is defiantely air/fluid escaping somewhere. the fact that it clamps UBER hard on one side is like the opposite is failing @ life. i would advise getting some friends without beer or drugs involved and check it down hardcore. bleed the brakes... observe all lines thoroughly. etc etc.

[Barefoot]

what your fluid levels look like

[DirtyMechanic]

if he has a leak im sure he would know about it very quickly. seeing as every time he hits the brakes fluid would come out due to the large amounts of pressure. i know on some cars the pedal drops a little normally no matter what you do. but usually you dont use a USED master cylinder. get a new one or one that you know works just fine, as in a running car and try that if that doesnt work then you might have a issue with your brake booster.

[punkr6]

what your fluid levels look like

x2 , lets start here

[Humphrizzle]

x2 , lets start here

he said he bled the brakes.. if he actually did this, he'd know his fluid levels were up to spec.

[Humphrizzle]

prop valve located somewhere in this region.

[Barefoot]

he said he bled the brakes.. if he actually did this, he'd know his fluid levels were up to spec.

ive learned my lesson with people around here. that lesson start with the basics and more up. just because he said he bleed doesnt mean it was anytime recently.

[speedminded]

ive learned my lesson with people around here. that lesson start with the basics and more up. just because he said he bleed doesnt mean it was anytime recently.

lol bingo! Always start with the most obvious. I called Comcast the other day with modem issues. The first thing they asked was, "Is it plugged in to a power outlet sir?".

You know, if never occured to me you actually have to PLUG in electrical devices, who would have though that?!! I guess they have to ask lolol!

[Krytdrgn]

I dont even know what you drive...

but it could be the brake booster. It could also be a vacuum leak in general of about any kind that can cause a problem.

[Humphrizzle]

wtf is that thing in your signature?

[green91]

Gees people there are some bad answers in here.

#1) A brake booster will NOT EVER cause a soft pedal. A bad booster will make the pedal HARDER.

#2) Are you sure they are bled correctly?

#3) Check for sticking slide pins on the calipers.

#4) Ive seen many new master cylinders that are bad.

[Humphrizzle]

i bled brakes that someone had just bled and got about half a pedal stiffened up.

[speedminded]

Gees people there are some bad answers in here.

#1) A brake booster will NOT EVER cause a soft pedal. A bad booster will make the pedal HARDER.

#2) Are you sure they are bled correctly?

#3) Check for sticking slide pins on the calipers.

#4) Ive seen many new master cylinders that are bad.

While we're on the topic of brake boosters can I put a fitting in one and run a remote reservoir off it to increase the volume? Larger booster means softer pedal right?

[Krytdrgn]

Gees people there are some bad answers in here.

#1) A brake booster will NOT EVER cause a soft pedal. A bad booster will make the pedal HARDER.

#2) Are you sure they are bled correctly?

#3) Check for sticking slide pins on the calipers.

#4) Ive seen many new master cylinders that are bad.

Depends on what is wrong w/ the booster. In my old truck, mine caused a vacuum issue causing soft pedal. I replaced the master cylinder first b/c it was already wearing out and then we looked and there were no leaks so it had to be the brake booster which fixed it.

[Krytdrgn]

wtf is that thing in your signature?

RSX-S... Cwest front... VIS hood...

Did a front end conversion-it's an 04 but put on 06/headlights/bumper

[green91]

While we're on the topic of brake boosters can I put a fitting in one and run a remote reservoir off it to increase the volume? Larger booster means softer pedal right?

Its the diameter of the actual master cylinder, that makes the difference, not the fluid capacity. Actually a larger diameter m/c usually makes the pedal harder because it moves more fluid with the same stroke as a smaller diameter master cylinder

[green91]

Depends on what is wrong w/ the booster. In my old truck, mine caused a vacuum issue causing soft pedal. I replaced the master cylinder first b/c it was already wearing out and then we looked and there were no leaks so it had to be the brake booster which fixed it.

For a vacuum booster to somehow make a pedal softer, you would have to increase the amount of vacuum going to it. A vacuum leak, hole in diaphragm etc would make your brake pedal harder due to lack of vacuum assist. I cannot think of a way that a bad booster would make your pedal softer.

[Krytdrgn]

For a vacuum booster to somehow make a pedal softer, you would have to increase the amount of vacuum going to it. A vacuum leak, hole in diaphragm etc would make your brake pedal harder due to lack of vacuum assist. I cannot think of a way that a bad booster would make your pedal softer.

If there is less pressure in the line the pedal travels easier.

Either way, if this is the case you should hear a suction type noise when you apply the pedal. If not then it is something else.

[green91]

You've really got me scratching my head. I dunno WTF you are talking about.

A (vaccuum) brake booster uses engine vacuum to help apply pressure to the master cylinder, to make the pedal softer. There is no pressure within the master cylinder, except on the pushrod to the m/c. If the booster is bad it will DECREASE the pressure output on the pushrod, thus making your brake pedal more firm. (less assist)

[Krytdrgn]

Right. But if there is no pressure then the pedal will travel w/o resistance. I would blead the lines and the brake would be extremely hard at first. Then (relatively quickly) it would allow more air into the system and reducing resistance on the pedal. I don't claim to be an expert but a friend on another forum (CRSX) explained it to me a while back and as soon as I told him the issue he knew the problem. I replaced it and it was fine

[green91]

A brake booster doesn't ever come into contact with brake fluid, nor could it allow air into your brake fluid, unless your master cylinder was bad.

[punkr6]

1-have you lost any fluid ?

2-you say the master cylinder was replaced with a used part, it could be bad as well.

3-you said the problem went away for a while when the ( used ) master cylinder was installed.

If you haven't lost any fluid its most likely a bad master cylinder...
__________________

[punkr6]

ive learned my lesson with people around here. that lesson start with the basics and more up. just because he said he bleed doesnt mean it was anytime recently.

or correctly...

[Krytdrgn]

A brake booster doesn't ever come into contact with brake fluid, nor could it allow air into your brake fluid, unless your master cylinder was bad.

I have no idea bro. I had just replaced the master cylinder. It all works now..

[JDM onlyy]

I believe they are talking to me. And the guy changed it with a used master cylinder from a working car, and then I changed it again with a used master cylinder from a known working car. Right after I did it, pedal felt great. After a few drives, it started feeling mushy and dropping to the floor again. It doe make a noise like some fluid squirting when I step on the brakes.

And its not UBER hard on one side, it just feels like the other side is UBER soft, so it pulls to the left when I step on it.

And the master cylinder has been changed twice, cause we thought it might be the brake master cylinder. So no go on that one, unless they're both messed up.

[JDM onlyy]

Just checked my brake fluid levels, shit was UBER low from like a month ago. Thats when I bled it. The fluid level was at or below the minimum, I can't really see in the dark, but I know it was mad low. I just refilled it. So, I'm going with the idea that my front right brake caliper is screwed.

Been meaning to check them fluid levels but I been forgetting. But yeah, so we can narrow it down to a leak somewhere now right?

Oh yeah, I forgot to mention that if I hold the brake pedal down at a red light, it falls down and I can hold it on the floor but eventually the brakes give up and I start to roll, so I have to pump the brakes to stay braking again.

[yunglaosta]

brake master cylinder that you bought used probaly went bad.

[JDM onlyy]

brake master cylinder that you bought used probaly went bad.

both of them are bad? what are the chances of that?

[Kaiser]

Do you have rear drums? Have you checked the rear wheel slave cylinders?

If you have 4 wheel disc, what your describing is absolutely a brake-pressure-equalization problem, which could be a leaking proportioning valve allowing air into the system. Or it could be from a bad caliper that is somehow allowing air into the system. If you've replaced the MC twice and that temporarily fixed the problem but it came back, then it's likely that something you did DURING the MC install process fixed the problem, NOT the actual MC itself. Like, I dunno, bleeding the brake system. Which would remove the air in the line.

Oh, and I kinda doubt that a bad brake booster would be in the world of possibilities for this. It's air in the line, the question is how.

[JDM onlyy]

Do you have rear drums? Have you checked the rear wheel slave cylinders?

If you have 4 wheel disc, what your describing is absolutely a brake-pressure-equalization problem, which could be a leaking proportioning valve allowing air into the system. Or it could be from a bad caliper that is somehow allowing air into the system. If you've replaced the MC twice and that temporarily fixed the problem but it came back, then it's likely that something you did DURING the MC install process fixed the problem, NOT the actual MC itself. Like, I dunno, bleeding the brake system. Which would remove the air in the line.

Oh, and I kinda doubt that a bad brake booster would be in the world of possibilities for this. It's air in the line, the question is how.

That's what I thought. So I was thinking its either my prop valve or my caliper. But I'm losing fluid too now, so I'm guessing its my front right brake caliper. Anyone got a good used one for cheap?

[Humphrizzle]

for what car?

[DirtyMechanic]

both of them are bad? what are the chances of that?

its used... Very good is the chance, because the car you took it off of or it came from DIDNT RUN. so what makes you think parts from it are good?

[Barefoot]

Just checked my brake fluid levels, shit was UBER low from like a month ago. Thats when I bled it. The fluid level was at or below the minimum, I can't really see in the dark, but I know it was mad low. I just refilled it. So, I'm going with the idea that my front right brake caliper is screwed.

Been meaning to check them fluid levels but I been forgetting. But yeah, so we can narrow it down to a leak somewhere now right?

Oh yeah, I forgot to mention that if I hold the brake pedal down at a red light, it falls down and I can hold it on the floor but eventually the brakes give up and I start to roll, so I have to pump the brakes to stay braking again.

i rest my case

[southside]

both of them are bad? what are the chances of that?

Stop being cheap and just get a new one see if that solves your problem.