When you catch a flying frisbee, you probably pinch it between your thumb and your fingers. The pads of skin on  your finger and thumb immediately stop the frisbee from rotating. 

disk brakes in automobiles work in a similar way, clamping two pads together onto either side of a spinning metal  disk.  Each wheel of a car has two brake pads set up to give it a squeeze when you press on the brake pedal. New  pads are about as thick as Twix bar, but after 12 thousand miles or so, the pads get worn down to the stump.

When the pads get worn down, they have a cheap, built-in alarm system. A little tab of metal begins to make contact  with the disk brake, every time you stop, creating a high-pitched squeal.  This squealing sound is your signal that it is  time to replace the brake pads. If you ignore this sound, your brakes will grind through the final layers of brake pad  material, and start to press steel plates against your iron disk brakes whenever you apply the brakes. Your car will  probably keep stopping, but each time you stop, you will be crushing, etching, scarring, warping, marring, twisting  and grinding up an expensive little clockwork of machinery that surrounds your wheels.

When you hear the squealing brakes, you have about three weeks to take care of it, or the price of repair will climb  from about $200 to about $800.

Changing the pads is pretty easy, but toying with your brake system can certainly be a little unnerving. 

When I changed Stacy's brake pads last summer, I took a bunch of photos to help illustrate the process. I hope these  help people who are having trouble changing their brake pads, and I hope that they inspire people to try the repair  themselves. 



Stacy's Hyundai Elantra 

First, go buy the parts. I went to Kragen and asked at the service desk for brake pads. They asked about the year,  make and model of my car. They had a few price options, so I asked for the cheapest one. I think it was $35.

The box came with four brake pads, four metal shims (anti-squeal shims) and a tiny packet of lubricating powder.  These four pads were what I needed to replace the brakes on the two front tires. Sometimes these four-pad boxes  are called "axle packs". 

This, or any operation is easier if you have access to another car, so that you can get back to the store when your  car is up on jack-stands and you need to get back to the store for that odd tool I forgot to mention at the start of this article.

Once you have bought the brake pads, got the car jacked up and pulled the front wheel off, the job is 2/3rds finished. 

A chunky iron caliper holds the brake piston (cylinder) and the pads together. On many cars, if you remove the lower  bolt, most of this big hunk will swing up and away from the disk and brake pads, making it a breeze to repair.

On the Hyundai, the top bolt is a great place to wrench onto and pivot the caliper housing out of the way. 

Once the caliper is out of the way, the old brake shoes will just be sitting there on both sides of the disk, ready to be plucked like a pair of ripe rusty apples.  You may wish to make a mental note, or sketch or photograph of how the brake pads are aligned as they sit in the caliper housing.  



anti-squeal shims 
if at first you don't succeed, lay on the horn and try to plow into something soft and cheap, like bushes, small fences,  realty signs or fruit stands.