here is my setup. i believe i have front pads from porterfield and stock rotors that have been turned once. the rears are all stock. at 60k ive never changed the brake fluids.

problem: at certain times the brake pedal is VERY mushy. its not smooth at all. everytime the pedal feels mushy, i hear a squealing or grind noise in the front.

anyone have some insight on this? i know it can be caused my warped rotors, air in the brake lines, or maybe even the harsh brake pads.

questions:
-how can i tell if my rotors are warped?
-how can i tell if i have air in the brake lines?

thanks.

 

Warped rotors can cause vibrations under braking.

As for the brake lines, just bleed them.

 

mushy feeling can come from air in brake lines. i highly doubt its from your rotors.. like dub sed, a warped rotor will give you vibrations you can feel through your steering wheel.

 

thanks for the info. how can i go about bleeding the lines?

 

 

Do you have to add brake fluid on a regular basis. A properly operating brake system will not consume fluid at a rate which requires regular replacement. Check for leaks especially around your master cylinder.

When you last did your brake job, did you be sure to lube the caliper slides? This is something that MANY people often forget and is very important. You will end up with uneven brake wear, warped rotors and a host of other problems.

 

this mussy feeling can come from a leak in the line due to a cracked hose. i would try to trace all the stock rubber brake lines first then bleed them if necessary.

 

If you have access to a micrometer, you can measure the width of the rotors at various intervals to determine if it is one thickness. If it's warped, you'll get different measurements.

Also, have you checked to see if you're just out of pad? Nobody's mentioned the possibility yet of one or more brake pads worn down to the backing plate. They may have been installed incorrectly, causing the premature wear. Pull your pads and look for even wear across the pads.

My mushy pedal feel was attributed to a failing brake master cylinder. If your rotors are not warped, your pads are not glazed over, you've bled the lines and have no air, then you may have a failing master cylinder. Can you determine where the noise is coming from? Is it coming from down at the wheels or somewhere in front of you?