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Mushy brake pdeal - change Master Cylinder

rickshaw

Full Member
Joined
Nov 29, 2007
Messages
57
Location
Vilano Beach, FL
I've spent a significant amount of time on the boards today researching the hundreds of posts on break issues.

My brake lines corroded to the point where one of the lines burst, so I had all 4 replaced, and the brakes were bled by a reliable mechanic.  I've had the mushy brake pedal for a while, changed the rears with Wagner ceramics that helped a bit, but it's getting to the point where I don't feel safe.

I noticed that my front rotors only show a wear mark of about 50% of the pad's size and suspect weak pressure caused by a bad Master Cylinder.

How do I know if the root cause is the Master Cylinder or Brake Pressure Modulator Valve?

Thanks for your responses!
 
On all my cars I check the master cylinder by taking off the top and have someone push the brake pedal, if you see fluid rushing into the reservoir chances are the seals are shot in the master cylinder.
 
Thanks for your advice!  I checked and there were no bubble or any movement in the cylinder.

Please give my regards to my peep's Downriver!

 
Pressure gage on both outlet lines.

Pressure gage after proportion valve as well
 
rickshaw said:
I've spent a significant amount of time on the boards today researching the hundreds of posts on break issues.

My brake lines corroded to the point where one of the lines burst, so I had all 4 replaced, and the brakes were bled by a reliable mechanic.  I've had the mushy brake pedal for a while, changed the rears with Wagner ceramics that helped a bit, but it's getting to the point where I don't feel safe.

I noticed that my front rotors only show a wear mark of about 50% of the pad's size and suspect weak pressure caused by a bad Master Cylinder.

How do I know if the root cause is the Master Cylinder or Brake Pressure Modulator Valve?

Thanks for your responses!
 
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