Brake master cylinder failure!

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gt4tified

New member
Anyone here ever had their brake master cylinder fail on them when doing a brake change?

I put on the single pot calipers and respective rotors and when trying to bleed them, the system is not leaking but after momentarily building SOME pressure, I lose it. I am sure I bled the system properly cuz I bled all four corners and went through at least a quart of good dot4 fluid! :x

So I took out the brake master cylinder and sure enough, the second (innermost) piston/spring had some corrosion/sign of wear. So I'll be searching for a rebuild kit today.

I just found it strange that since I did not mess with it, that it decided to fail on me just by bleeding my new brakes. :shrug:

Would the brake booster suddenly develop a problem, if there was none before? I'm just trying to attack all the weak links before I get the master back up.
 
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esracing

Member
some master cylenders go bad when doing brakes because when you pump the pedal to the floor to bleed the system the piston wipes crost the area it has not ben travaling and it cuts the seal . i recc that you replace the master cylender insted of rebilleding it.
 
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gt4tified

New member
esracing":2mdwc3to said:
some master cylenders go bad when doing brakes because when you pump the pedal to the floor to bleed the system the piston wipes crost the area it has not ben travaling and it cuts the seal . i recc that you replace the master cylender insted of rebilleding it.
Click to expand...

Lol....I would...but parts for my car are not available at the local stealership and I can't wait on shipping a part from Japan....might have to check in one of the other islands though.
 
D

darthripley

Moderator
are you trying to get all the fluid out of both the master & the reservoir?

we use a syringe like a plastic one that you might use to give liquid medicine to a pet with. it works like a charm to suck all the fluid out.
 
G

gt4tified

New member
Well guys and gals,

I successfully replaced the seals in the master and bolted back up...bled the system with the engine off...everything fine....turn on the car and from the minute I press the pedal the car loses vacuum.

I unplug the vacuum line from the booster and clog it with my cousin's finger lol (he helped me) and voila perfect brake!

So I guess now its back to the drawing board.....gotta find a booster!

Oh well, at least I won't have to go through this for a long time again!

*sigh*
 
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gt4tified

New member
Ok so I got a used booster from another 185. It definitely builds pressure with the car off and with the car on, its a bit spongy but initially from about mid-way down I get brake. Someone told me that as long as you mess with the rotors and calipers I'd need to adjust the booster....something about the diaphragm needing to compensate.

Anyway, that was yesterday. This morning on my way to work, the pedal started losing pressure again and I'd barely get any brake....only about an inch before the pedal hits the floor. Needless to say, its not stopping the car, only slowing it down! I'm not seeing air being drawn in anywhere and there are no leaks in the system. And yes the system was again bled properly!

Need some help with this please.....
 
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alistair

New member
I just had the same problem. My brakes were fine, took off one of the calipers to change the pads on it and relube the one shaft. Left it for about 2 weeks and afterwards my brakes didn't work worth squat.

there was some gouging on the inside of the brake cylinder, so I think I'm going to have to replace the whole thing.

*sigh* I wonder how much the stealership wants for a master cyl. Which of course will come from California which means of course I won't get to drive my Alltrac for another 2 weeks.

Summer is gonna be over here before I get to drive my car :cry:
 
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Smaay

Member
im having clutch master cylinder problems. if i hold the clutch down for more than 5 seconds it stays on the floor and the clutch will start to engage.
 
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Fox 21 Alpha

New member
Same problem man, new rotors and pads all around. Pedal will slow the car but goes straight to the floor unless you pump it a few times, and if you let the pedal out it will lose that pressure. Replaced the master cylinder, brand new, original manufacture brand too, didn't do shit. No air in the system and don't lose a drip of fluid. Even replaced the brake lines in the shitty part. I'm at a loss.
 
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