When the pedal is depressed, it pushes on a piston (inside the brake master cylinder) which pushes the brake fluid through the brake line.  The fluid pushes inside of either the wheel cylinder (drum brake) or the brake caliper (disc brakes).  The wheel cylinder then pushes out against the brake shoe, causing it to rub against the brake drum (which is attached to the wheel).  The fluid inside the brake caliper pushes the piston’s caliper out against the brake rotor (aka the disc, which is attached to the wheel).

        Begin by looking at the insides of the wheels from underneath.  Check for signs of brake fluid leak.   Then check around the brake master cylinder for leaking of fluid.  Finally, be certain there is enough fluid in the master cylinder.   If you know the car can be driven reasonably safe as is, begin with a road test.  Find an unoccupied stretch of road and test the brakes from about 30 mph.  Maintain a light grip on the steering wheel and verify that the car stops without pulling to one side.  You may even choose to have your hands just slightly off the wheel.  If the car pulls to one side when the brakes are not applied, it could be a dragging brake, but is more likely a problem in the steering or front suspension.  If it pulls only when the brakes are applied it is most likely a sticking caliper or sticking wheel cylinder.  Notice also if the brake pedal pulsates.  If so, one or more of the brake drums or rotors are out-of-round.  An out-of-round brake rotor or drum could also cause a shimmy but this could also be the fault of worn parts in the steering.  If a shimmy or pulsating pedal are detected the brake rotors and brake drums will have to be checked for roundness.
        Back in your garage, begin by putting the front of the car on jack stands and blocking the rear wheels.  Pull off the front wheels.  If you have front drum brakes it will be necessary to remove the wheel bearing to get the wheel off.   Once off, pull the brake drum off and set it aside.  Spray the brakes with brake parts cleaner.  Examine the shoes to see if their linings are down to the rivets.  If so, all shoes on that end (i.e.-front or rear) of the car must be replaced.  Remember this eternal brake system rule: if one brake shoe on an end of the car needs to be replaced they must all be replaced on that end.  If the lining is held on by adhesive (and not rivets) it should be at least 1/8 of an inch thick.  If you have any doubt about the thickness of the shoes, take the car to your trusted repair shop for their opinion.
        You should have examined the wheel cylinders and flexible brake lines for leaks.  If they have any, they should be replaced at this time.   If the car is more than 20 years old or so you may want to replace the wheel cylinders just to be on the safe side.  They can spring a leak at any time and you don’t want it to be while rolling down the road.  You want to be able to stop rolling.
        Now examine the drums.  If they have grooves in them they will need to be “turned” at a repair shop.  Check the shop manual for the minimum thickness that the drums or rotors can be.  This should also be indicated on the drum but if you can’t find it, the manual will indicate it.  And regardless of the thickness of the shoes, they will need to be replaced if the drums are grooved, for they will have matching grooves. Follow the instructions for tightening the wheel bearing when reinstalling.  If it is too tight it will wear out rapidly.  If too loose it could cause a wobbling wheel, and like a tight wheel bearing, will wear out prematurely.
        If you have front disc brakes the thickness of the pads can be seen by looking down into the caliper.  Look for the part of the caliper that comes in contact with the rotor.  Those are the pads.  The part in contact with the rotor is the lining of the pad.  It is attached to the backing.  The lining itself should be at  least an eighth of an inch thick.   If in doubt,  have the repair shop look at it.
        When you test drove the car you were supposed to see if the pedal felt mushy.  Does it feel much more so than any car  with properly performing brakes?  The pedal feel from one type of car to another will vary but not so much that you feel unsafe with your car.  If possible, try another car of the same year and/or type that you know has good brakes and see how that pedal feels.  Also, if the pedal sinks to the floor while sitting at a stop it will need a brake master cylinder.  Ditto if the pedal feels too mushy.
 
        Something to consider.  We discussed earlier the reasons why it would be necessary to replace the master cylinder, the wheel cylinders, and the flexible brake lines.  If these parts show no signs of being defective you can get by without replacing them.  However, they can go bad with little notice, and if you’re far from home you may find yourself wishing your car did have an anchor.  Thus, give some thought to replacing these so that you know you have good ones.  Then, you can save the old ones in a heavy-duty plastic bag for your emergency spares kit.  And remember, brake fluid will remove paint so be careful when storing these old parts.

        Check your shop manual or owners manual to see if your car has an emergency brake light.  See if it also functions as a warning that there is a pressure loss in the system.  Verify that this light is working properly.  It may save your life.

        We have now done the front brakes.  If the rears are disc they will be the same as front disc and if drums then the same as those.   And don’t forget, always repack any wheel bearings when you take them out.  That way you don’t have to worry about doing it again after the car has gone a certain number of miles.

        There is an anchor or sorts on a car and it is the emergency brake.  Normally it can also function as a brake that will get the car stopped.  Test it to see if it will keep the car still on a hill.  It may need to be adjusted if the pedal goes all the way to the floor.

        You’ve now gotten a good idea of the condition of your brake system.  Any repairs should be performed by a qualified service professional.  Brakes do not suffer fools lightly.  You may wish to have them perform a thorough check.  The checks we have discussed here are so that you will have an idea what to expect when you take it to your repair shop.   Join us again next time when we will satisfy ourselves that your fuel system is safe and sound.