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What the HELL is wrong with my brakes?!

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Old Apr 24, 2006 | 07:31 PM
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Default What the HELL is wrong with my brakes?!

I've got a 96 Accord EX. That's discs all around baby!
Just did a brake job on all four tires, flushed the lines with new brake fluid at the same time.

Now about 300 miles later I'll be sitting at a stop light and the pedal will gradually go to the floor and I'll be standing on it to keep the car from moving on me. If I (while holding the handbrake) release the pedal and re-apply preassure it's firm again. Under all other conditions the pedal gives me good resistance and the ABS kicks in just when it should.

The first thing I did was re-bleed the lines, but there was no air in them anyway.

What in the world is wrong?
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Old Apr 25, 2006 | 12:02 AM
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From: six-five-o
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might be master cylinder then
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Old Apr 25, 2006 | 07:56 AM
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Originally Posted by wedley2
might be master cylinder then
Yeah that's what I thought too, but I'm not familiar with them.

Try a search for that.
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Old Apr 25, 2006 | 12:11 PM
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We need to trouble shoot this.

1. When the pedal goes to the floor are you loosing fluid somewhere, anywhere?

I.e. if the pedal's on the floor the piston moved out in the cylinder, either fluid went to the calipers or it didn't, if it didn't where did it go. Is the cap on tight did it go out the top of the res.?
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Old Apr 25, 2006 | 02:51 PM
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the usual problem with master cylinder from what ive heard is requiring to pump the brakes to gain pressure tro the pedal.

if it was a failing brake booster, one wouldnt get any leverage to the brakes.

if you completely bleed the brakes, then it should be the master cylinder.
remember to bench bleed the MC b4 installation
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Old Apr 25, 2006 | 06:04 PM
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Originally Posted by MrChad
We need to trouble shoot this.

1. When the pedal goes to the floor are you loosing fluid somewhere, anywhere?

I.e. if the pedal's on the floor the piston moved out in the cylinder, either fluid went to the calipers or it didn't, if it didn't where did it go. Is the cap on tight did it go out the top of the res.?

No leaks! My first thought was I snagged a brake line or the caliper pulled one too tight when I was putting new pads on, but lo-and-behold there's no loss of fluid at all. The cap's on tight too.

-rp
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Old Apr 25, 2006 | 06:06 PM
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Does the engine idle funny when you loose the brakes?
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Old Apr 25, 2006 | 07:01 PM
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Originally Posted by MrChad
Does the engine idle funny when you loose the brakes?
Nope.

After my last post I did some HAN research on master cylinders. I'm leaning towards a bad master cylinder now.... When I bled the brakes I pushed the pedal all the way to the floor, and it seems YOU SHOULD NOT DO THAT!!! Corrosion at the end of the cylinder eff's up the seal since the pedal really never gets pushed down that far. Ooops.

My favorite way to learn something is the hard way. Duro de aprender, pendejo.


Now my attention is focused on how I can rebuild the MC instead of replacing it. Unfortunatly HAN research is coming up short in this area....
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Old Apr 25, 2006 | 07:13 PM
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If you have pitting (corrosion) it'll most likely need replaced sorry...

How do you bleed brakes without going to the floor? This worked fine for me.
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Old Apr 25, 2006 | 07:17 PM
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Originally Posted by MrChad
If you have pitting (corrosion) it'll most likely need replaced sorry...

How do you bleed brakes without going to the floor? This worked fine for me.
What I read suggests that you only press the pedal halfway down when bleeding an old master cylinder. I guess this would take longer....
The smart way is to spend 30 bucks on a friggin' vacuum hand pump. As many brake jobs as I've done I can't belive I havn't bought one by now.

BTW, what would the "funny idle when brakes die" symptom have meant, had that been the problem?
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