Brakes are crucial to any automotive vehicle, it can be a life or death situation.
Which makes getting them fixed a 1# priority.
"Brake pedal going to far and not stopping the vehicle fast enough."
Low Brake Fluid
Check your vehicle Brake Fluid level in the brake reservoir & fill if it's not in between the min & max markings.
Brake Fluid Contamination
Sometimes brakes can get water in the lines from condensation caused by outside temperature levels. The best way to check, is to bleed the Slave Cylinder by cracking usually a 10mm nipple that will release the brake fluid, the slave cylinder is located on the brake caliper and brake drum. Always make sure to keep the brake booster reservoir full while bleeding, or you will pull air in the system and create another problem.
Worn Brake Pads
A worn brake pad will scream like fingernails on a chalk board, or just like your local garbage truck coming to an abrupt stop. There is a telltale prong on every vehicle brake pad. When the pad gets too low, the metal prong touches the brake rotor and screeches letting you know it's time to change the pads. After weeks of not changing the pads, the prong will start to put grooves in the rotor causing the repair bill to be even more costly. You'll either need New Pads & New Rotors, or New pad's & turned rotors".
Bad Brake Booster Unit
When a Brake Booster goes bad, usually the pedal never builds pressure at all. This also could mean a bad Slave Cylinder as well. The only way to know for sure that it's your Brake Booster, is to get a special Vacuum Measurement Tool that hooks up to it. (Final note), don't forget to check the "check valve" on the vehicle inside the brake boosters line going from the brake booster, to the intake manifold, if that is clogged, that will cause a problem also.
"Brake Pedal Too Stiff"
No brake pedal should feel like you're squatting 1,000lbs at the local gym, if this is the symptom, here are a few possibility's.
A Brake Booster runs off vacuum created by the engines intake system, a leak in any vacuum line will cause the entire system to loose pressure thus making the brake booster loose pressure causing the pedal to be firm.. check all Vacuum Lines for leaks.
Damaged Brake Line
A kinked Brake Line will definitely cause a stiff pedal, check all lines for possible kinks due to hitting something on the road.
"Brake Pedal Goes To The Floor"
When you push a brake pedal it should never feel like it just flops to the floor without any resistance, if this is the case check these.
Low Brake Fluid
If your Brake Fluid is low, you could have a leak in the system, top it off to the max fill mark and watch it over the course of the next few days. If the pedal doesn't get firm, bleed your Slave Cylinder and keep the Master Cylinder reservoir full so no air is pulled in. After you feel that all the air is gone, tighten the slave nipple, and test it out.
Bad Master Cylinder/Slave
Sometimes they just go bad, if it's the last thing on your check list, and you still have the problem, well.. it's time to replace it. Testing the Master Cylinder on your vehicle requires a special Vacuum Meter. Seeing the prices of parts on eBay nowadays, it could be in your best interest to just snag one off the internet and call it a day. As for the slave, a rubber hydraulic like plunger after time can deteriorate away, then it's time to replace the entire unit.
Brakes should have a smooth transition, if yours seem to have a less appealing affect you might want to look into these ideas.
Brake dust can cause Brakes to grab, sometimes brake dust gets stuck on the pad tracks causing the pad to jam, then you apply more force to the pedal and bam! a nice jolt to the head. To solve this, simply pull the tire off and hit the pad track with some Brake Cleaner.. put the wheel back on, and test it out.
Warped Brake Rotor
A warped Brake Rotor can also cause a jolting grab, if the rotor is warped, it's time to replace it with a new one.
"Brake Pedal Goes Up & Down With My Foot On It"
This is a classic warped Brake Rotor, what happens is the the rotors warped side goes out pushing the brake pad out causing your foot to follow with it. The brake pedal controls the brake pad, when the rotor pushed the brake pad, it also is pushing your foot.
Bad Wheel Cylinder
A bad wheel cylinder can cause your Brakes to stick, usually the only way to fix one is by replacing it.
E-brake Not Releasing
Sometimes a e-brake can and will get stuck, first thing to try is if your on a decline, put your vehicle in either drive or 1st gear and roll forward while holding the e-brake button in and releasing it. if your on flat ground do the same but instead put it in reverse and try to roll back a hair. If that fails then your e-brake cable might need to be lubricated. Simple track down your E-Brake Cable under the vehicle and spray some good old wd-40 on it.
"Vibrating Brake Pedal"
Two things come to mind, 1) being the metal gasket is missing between the Brake Pad and the piston, allowing the vibration. 2) You need to apply Anti-Squeal Lubricant to quiet the noise vibrations. Brakes Sound Loose, this could be anything from Brake Caliper bolts, to strut bolts ect. Best thing to do, is crawl under the vehicle with a flash light, and carefully check the brake rotor areas for missing or loose bolts,also check the connecting tie rods.