Brake Fluid and Hydraulic Components Government regulations specify the hydraulic fluid used in brake systems. Brake fluid is exposed to a very wide range of temperatures from ambient temperatures far below zero to near one thousand degrees of glowing hot metal under hard braking. One relatively unknown characteristic of brake fluid is its tendency to absorb moisture. The master cylinder has a small reservoir of fluid with a sealed cap to limit exposure to atmosphere. Over time, however, some moisture is inevitably absorbed by the fluid. Owners of older cars need to be aware of problems associated with contaminated fluid and have brake fluid changed at the fist sign of problems Spongy pedal feel, brake sticking, and brake failure during sub-zero weather are some symptoms. (Moisture in brake fluid can freeze). Brake fluid is clear and colorless. If it is cloudy, brown or has visible contamination it should be replaced throughout the system.
this is not a do-it-yourself project
Any brake inspection or re pair should include a visual examination of the brake lines Metal and rubber brake lines under a car are subject to damage from road debris Rubber lines can deteriorate with age and develop leaks. A few minutes looking at brake components under a car can prevent dangerous problems on the road.
The master cylinder is the “master” of the system. Master cylinders and the small cylinders in the calipers (often called wheel cylinders) are best left to the professionals A brake safety inspection can find indications of problems such as leaks but the repairs are best performed by a brake shop.
There are some additional components such as proportioning valves, anti-lock brake systems, warning lights and parking if emergency brakes that are beyond the scope of an article about basics.
Signs you need to have your brakes checked
There is very little that can match the panic that follows when a brake pedal goes all the way to the floor without effect on the vehicle speed. Modem vehicles have dual systems that make a complete system failure very unlikely. Pro portioning valves and similar devices in the hydraulic system include sensors and switches to detect a severe imbalance of pressure caused by failure of one of the dual systems. If the brake warning light on the dash comes on, carefully get the car to a re pair shop, even if the brakes still seem OK.
Many vehicle manufacturers include a brake wear warning device. An annoying, high-pitched squeal every time you apply the brakes is a sure sign of a problem. Jerking or vibration in the steering wheel during braking is a sign of rotor problems. A spongy or slowly descending brake pedal is a sign of possible master cylinder problems. If you find yourself using more foot pressure on the pedal to stop your vehicle you need to get your brakes checked. Under severe braking conditions such as long downhill grades brakes can get so hot that fluid boils or the pads loose their
friction properties When this happens (if you survive) you need to find a place to allow the brakes to cool and, after the trip is complete, have your brakes checked for heat damage or fluid deterioration. Older vehicles have drum brakes on the rear wheels with a more complex mechanical configuration. Other than the drums and shoes in place of pads and rotors the systems operate the same.