How Brake Relining Works
So you've determined that noise is indeed coming from the front brakes, where most late-model cars have their disc brakes.
Before you take your wheels apart, peek into the inspection opening in the brake caliper. Can you see the line of the friction material? If there's less than 1/4 inch of friction material, it's about time to replace the brake shoes. If there's less than 1/8 inch, you have no time to waste -- the lack of friction material could be dangerous. And it could be causing damage to the brake rotors, which can be more costly to fix.
Now, repeat the whole process for the other front brake. And -- very important -- put the wheels back on.Now let's get this puppy on the road. Professionals refer to this process as "burnishing" the new brake pads [see sidebar]. The heat and friction of driving are what get the new pads working their best. However, that means that you want to avoid excessive heat before the pads are ready to handle it.
- If you drained any brake fluid from the piston reservoirs, replace it. Some mechanics recommend changing your brake fluid as part of this process, but you're not going to ruin everything if you reuse the old brake fluid.
- Again, don't overheat the brakes. Don't brake suddenly, and try not to bring the car to a complete stop until you're done burnishing. And when you're done, don't drive the car again right away. Let it cool.
- Accelerate gradually to about 45 mph. Then brake gradually to about 5 mph. Drive at that speed for about a minute. Then, accelerate gradually to 45 mph again, and brake gradually again. Repeat the process at least ten times.
- Try to pick a relatively unused road, and remember to leave yourself more stopping distance than you think you'll need. You're testing the brakes because of the possibility, however remote, that they might not work.
- As you drive, listen. You may hear some squealing as the brakes adjust to the new pads. It's probably nothing to worry about, but if it persists, you may want to take a closer look at your work. Make sure all the clips and bolts are attached with uniform tightness.