Awhile back I had my brakes fail suddenly. In other words, I had noticed them getting a 'little' mushy the week prior but then they just failed completely all at once, driving along and the pedal went right to the floor with nothing. I took it to the shop and they told me the master cylinder had failed completely, they replaced the master and checked the pads (which looked OK) and it seemed fine for a couple months. Now it feels like the brakes are getting mushy again (no resistance at the top end, it doesn't actually brake until you get close to the bottom). What the hell could be going on here and how do I fix it properly for good?

thanks

PS: fluid level is right at the top

 

Check your fluid, is it low? Could be a leaking caliper...leaking brake line....those are the two most probable reasons I can think of.

 

Nope, should have mentioned that but the fluid is topped off

 

Sounds to me like it's your master cylinder again.

 

i know right? i guess maybe i could have gotten a dud?

 

If you're not losing allot of fluid, check your floor board behind your carpet to see if the MC is leaking at the piston. I had an issue years ago with an MC getting too hot from a header pipe, had to go to DOT4 fluid and put a heat shield under the MC to fix the problem. The heat shield was easy, just a 4X8 piece of stainless bent into a U with tabs to attach to the existing mounting bolts at the fire wall or booster.

 

Is it always mushy or only after you drive awhile? If only after yu drive, you may have the wrong fluid in it. Disk brakes get hotter than drums and the fluid will boil if it is not the correct type. Once it boils, it is just like having air in the system. Are you sure that your circuit cut-off valve is not thrown?. Take the lead off and ground it to insure that the brake failure indicator light lights up, not just lighting when you turn the key. You could be using only the front or rear brakes. Mustangs did not use the cross , front right -rear left system but front or rear.

 

What fluid are you using and how are you using the car? Repeated stop from 1** will cause fade. Also, what pad are you using?

 

I think it could be air in the lines. You can have someone help bleed the lines and watch for any air to come out it does not take much to make the pedal mushy.

If there is air the question is where is it coming from as others suggested look for leaks.

-Gun

 

it is either the MC or a caliper/wheel cylinder or air in the line. thats all it could be if your fluid stays topped off and is not leaking.