|
One of the biggest enemies of your car's brakes is
heat. Think about the fact that the same amount of work is performed to
slow your car down as is performed to speed it up. That means that you
produce a lot of heat going down hills. Most engines have coolant, a
water pump, and a radiator to dissipate the heat of making the car go.
The brake system has to do the same job with fewer tools.
The main way to get rid of heat is for the surface of
the disks to absorb it and spread it out through the metal body of the
disk and from there to the air rushing by the disk. Normally this
system works fine If the brakes are applied steadily over a period of
time, though, the disk has no chance to get rid of the heat. If the
heat builds up long enough, the brakes get hot enough to be damaged and
then rendered ineffective. "Brake fade" means that the brake pedal
feels fine but there is no longer adequate friction between the pad and
disk. If the brake fluid reaches the boiling point, some of the fluid
or contaminants (like water) mixed with the fluid boil and turn to gas.
Unlike liquids, gases compress easily. The formerly firm brake pedal
gets mushy or goes to the floor.
To avoid overheating the brakes, the driver should
make sure to have the engine do some of the braking when going down
long hills. That means that the transmission should be shifted into a
gear that lets you take your foot off the brake pedal a fair amount of
the time, thereby giving the brakes a chance to cool.
Another precaution you can take to prevent brake
problems connected with overheating is to keep your brake fluid clean
and pure. Your shop can help you do this by flushing the brake lines or
by periodically replacing some or all of the brake fluid.
| 
