rubber section of brake line to caliper clogged and in need of replacement
Disc brakes at the top of the caliper Drum brakes at the top of the wheel cylinder
The next time the brakes are stuck engaged, try opening a bleeder in one of the calipers to see if the pressure releases or not. If the pressure releases I would suspect a faulty master cylinder. If only one caliper is stuck, it could be a collapsed brake hose, stuck slider pins or a stuck caliper piston.
The most important use for the bleeder valve is to remove air from the braking system. As air rises and will not flush out of a bleeder mounted low on the brake the bleeder needs to be at the top.
same as a car, take the caliper off, and leave bleeder to the top, build pressure, hold, open bleeder, repeat.
contaminated or warped brake piston. or warped or undersized rotor
The bleeder valve is a 8mm bolt for the rears located on top of the drum or on the caliper itself if you have disk rear brakes. For the front, a 10mm bolt is located on the caliper itself. PB blaster should be used to be sure the bleeder valve is not broken
Vibration when applying brakes is most likely warped rotors. Another cause could be loose caliper bolts.
Pads loose in caliper? Anti-rattle clips not installed or installed incorrectly?
located on each brake caliper/wheel cylinder for drum brakes. have an assistant pump brake pedal several times then hold down. open bleeder valve. repeat on each wheel until only fluid comes out. top off master cylinder as required. I suggest using line wrench on bleeder screws.
After you install the caliper, to keep the mess to a minimum, use a length of rubber hose that fits snug over the bleeder and direct the other end of the hose into the bottom of a clear container, open bleeder valve, remove master cylinder cover, keep reservoir full with new brake fluid (do not let it go empty if possible), let gravity fill the caliper and gravity bleed the majority of the air out. When you no longer see bubbles coming out from the hose bleed the brakes as you normally would.
check for loose caliper bolts, brake pad may be moving around in caliper or caliper bracket. missing or broken brake hardware.
The piston is forced out of the caliper by the pressure of the brake fluid. This pushes the brake pads against the rotor, in turn stopping the vehicle.