Answer did ya' bleed 'em? there may be air in the lines.
Be sure the new master matches the old master exactly and bench bleed the master before you install it.
Its a bad cylinder spring
Master Cylinder seals are defective. Replace the Master Cylinder ASAP. Stop driving the vehicle until you have this repaired. The brakes can fail completely at any moment.
Most likely brake master cylinder.
Wheel cylinder (drum brakes) or caliber (disc brakes) sticking. If you find this to be the case you need to replace both sides and replace your brake fluid which is contaminated with moisture.
make sure it's not the rear brakes hanging up, see if they feel hot, if you have drum brakes on the back a wheel cylinder could be hanging up.
May be the proportioning valve by the master cylinder
Bad fluid in master cylinder,flush system,bleed brakes
the rear brakes are grabbing. the linings may have fluid on them from wheel cylinder leak or dust buildup. sanding the shoes may help .
the friction between the brakes and the wheels.
the brakes or the emrgen see brakes
ABS brakes are not spongy. If you have spongy brakes the reason is that there is air in the system. You need to have your brakes bled.
probably not your engine, sounds like its time for new brake pads. if this doesnt correct it have the master brake cylinder checked
If the brakes are too loose that could be a result.
If your power brake booster (the large roundish metal thing that the master cylinder is bolted to) either fails or loses its source for vacuum then your brake pedal will become very difficult to push like if you have manual brakes.
Simply put, friction. If your brakes are overheating then you may have a caliber or wheel cylinder sticking. Replace the part that is sticking and replace all the brake fluid as it is more than likely contaminated with moisture which cause the parts to rust.
brake switch out of adjustment, master cylinder comp port plugged, rear brake hose collaspsed or ebrake cables seized
your brakes are about to give out... you should go to wal-mart and have them replace them
not enought fluid pressure, mis ajusted linkage,you need to ajust the ban tension in the trans, that wold be my gess
it is friction and when the water goes on the brakes and tires they bond together
cylinder stop drag
he he he