Master cylinder wasted?... check my logic
06-15-2009, 08:41 PM
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Master cylinder wasted?... check my logic Hey guys,
About a year ago (which was only about 1k miles ago, sadly) I put on new rotors and pads, painted the stock calipers, and put on steel braided lines. The brakes were firm, and all was well. When I was at the track last week I realized that the brakes were getting soft. It got worse throughout the day, and by the last run I could barely stop by the end of the shutdown.
I checked the reservoir, and it was still just a hair over the max fill line, so I don't believe I've lost any fluid. I just bled the brakes, and there was no air in them that I could see. They still feel really spongy. Since there's no air, they feel spongy, and there's no loss of fluid, I'm assuming this means my master cylinder is gone? If it was a caliper, I imagine I'd lose fluid. If it was a leak, I would lose fluid and probably have air in the lines.
Do you all agree? Anything else I should check first?
About a year ago (which was only about 1k miles ago, sadly) I put on new rotors and pads, painted the stock calipers, and put on steel braided lines. The brakes were firm, and all was well. When I was at the track last week I realized that the brakes were getting soft. It got worse throughout the day, and by the last run I could barely stop by the end of the shutdown.
I checked the reservoir, and it was still just a hair over the max fill line, so I don't believe I've lost any fluid. I just bled the brakes, and there was no air in them that I could see. They still feel really spongy. Since there's no air, they feel spongy, and there's no loss of fluid, I'm assuming this means my master cylinder is gone? If it was a caliper, I imagine I'd lose fluid. If it was a leak, I would lose fluid and probably have air in the lines.
Do you all agree? Anything else I should check first?
06-16-2009, 11:13 AM
#2
If you are losing a Master you will either not be able to pump them up to firm, or you can, but as you foot stays on the pedal it'll fall away since it can't hold pressure. It can and does happen, I've lost two on my Camaro.
But it sounds more to me like you may have cooked your pads and/or fluid.
But it sounds more to me like you may have cooked your pads and/or fluid.
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06-17-2009, 08:24 AM
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Thanks for the reply, Sam. I bled the system pretty thoroughly, and the problem persists, so I assume it's not the fluid. The pads are very new, and I know they have plenty of friction material left on them. Is there another way they can be "cooked"? Can they be glazed or something such that they no longer grab?
The pedal is very soft and spongy, but it doesn't seem to fall slowly like if there was a leak. I'm still thinking master because the way it faded away more after each run just really felt like a hydraulic failure to me.
If it is the master, I wonder if I should get an aftermarket master or just another stocker. Hmmm...
The pedal is very soft and spongy, but it doesn't seem to fall slowly like if there was a leak. I'm still thinking master because the way it faded away more after each run just really felt like a hydraulic failure to me.
If it is the master, I wonder if I should get an aftermarket master or just another stocker. Hmmm...
Last edited by Gauge; 06-17-2009 at 08:43 AM.
06-17-2009, 08:43 AM
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Could the fact that the car is supercharged have anything to do with it? I ran the vacuum line for the BPV off the line feeding the brake booster. The boost gauge shows 12psi of vacuum at and idle, so I assume it's getting the vacuum it needs.
I had discounted this before because when you shut the car off (i.e. no vacuum) the pedal feels firm, but you just don't get much braking power when you step on the brakes hard. That's not how it feels now. The pedal is soft, and it doesn't take much to depress it most of the way to the floor.
I had discounted this before because when you shut the car off (i.e. no vacuum) the pedal feels firm, but you just don't get much braking power when you step on the brakes hard. That's not how it feels now. The pedal is soft, and it doesn't take much to depress it most of the way to the floor.
06-17-2009, 10:04 AM
#5
Thanks for the reply, Sam. I bled the system pretty thoroughly, and the problem persists, so I assume it's not the fluid. The pads are very new, and I know they have plenty of friction material left on them. Is there another way they can be "cooked"? Can they be glazed or something such that they no longer grab?
The pedal is very soft and spongy, but it doesn't seem to fall slowly like if there was a leak. I'm still thinking master because the way it faded away more after each run just really felt like a hydraulic failure to me.
If it is the master, I wonder if I should get an aftermarket master or just another stocker. Hmmm...
The pedal is very soft and spongy, but it doesn't seem to fall slowly like if there was a leak. I'm still thinking master because the way it faded away more after each run just really felt like a hydraulic failure to me.
If it is the master, I wonder if I should get an aftermarket master or just another stocker. Hmmm...
The fact the pedal doesn't fall away is proof it's not a hydraulic leak. You can easily glaze pads. I don't know what you are running, but since you haven't mentioned it I have to assume the are cheapies that just can't deal with the pounding and glazed or maybe even cracked.
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06-17-2009, 12:27 PM
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They're Hawk HPS pads. I really never have liked them, but they came in a kit with the rotors. Still, if it were the pads, I would assume I'd still have a firm pedal, but I'd have to press really hard to get the desired stopping power. This isn't the case, though, since the pedal is soft.
With enough effort, I can push the pedal to the floor. However, if I put a consistant amount of pressure on the pedal, it seems to stay in place and not slowly fall.
With enough effort, I can push the pedal to the floor. However, if I put a consistant amount of pressure on the pedal, it seems to stay in place and not slowly fall.
06-17-2009, 12:36 PM
#7
HPS shouldn't be a problem, I use them and not only like them, but prefer them to most others available.
Maybe a caliper is stuck?
Maybe a caliper is stuck?
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11-29-2009, 02:36 PM
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Well, here I am almost 6 months later finally getting the car under the knife. The brakes were the least of my problems, but a problem nonetheless.
I just took one of the calipers off and looked at the pads. I haven't changed more than handful of brakes in my life, so I'm no expert, but they look somewhat normal to me. There's a little bit of a sheen to the surface, but it still appears to have some texture to it. I'll try to get some good pictures, but my camera is dead, so it may be a few days before I can borrow one.
One thing that occurred to me is that perhaps it's the rotors? The rotors are from BSI, that company that scammed a bunch of people and eventually were booted from the site because of it. They look normal to me, but I don't know.
Thoughts? Suggestions?
I just took one of the calipers off and looked at the pads. I haven't changed more than handful of brakes in my life, so I'm no expert, but they look somewhat normal to me. There's a little bit of a sheen to the surface, but it still appears to have some texture to it. I'll try to get some good pictures, but my camera is dead, so it may be a few days before I can borrow one.
One thing that occurred to me is that perhaps it's the rotors? The rotors are from BSI, that company that scammed a bunch of people and eventually were booted from the site because of it. They look normal to me, but I don't know.
Thoughts? Suggestions?
11-29-2009, 04:29 PM
#9
sounds kinda like the brake booster is bad honestly. I had a similar problem where the brakes were very soft until i got about half way down then they started to grab but were real touchy. turns out the new brake booster i bought was bad. replaced it with an original and everything is back to normal.