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Replacing Front Brake Pads Front brakes starting to squeal? It's probably time for a new set of brake pads. While we've all heard stories about how difficult it is for the home mechanic to work on today's computerized brake systems, replacing a set of brake pads is well within the bailiwick of the average Do-It-Yourselfer. The mechanical components of disc brakes are the same—with or without Antilock Braking Systems. Let's see what's involved. First, loosen (but do NOT remove) the lug nuts on the front wheels. Once the lugnuts are loose, jack up the front of the car and place it on a set of jackstands. Then, remove the lugnuts and the front wheels. If you're not 100% confident of what you're doing, work on one side at a time. That way, if you forget how something goes back on, you'll be able to refer to the other side. In this article, we'll be working on the passenger side of the car. Removing the Caliper
The procedure described here is a little bit different from the procedure described in the Acura Vigor Service Manual. We've chosen to do it this way because (1) this procedure will work on the front as well as the rear, and (2) this is the way the author likes to change pads. Refer to the photo at right. The two white arrows point to the caliper bolts. The blue arrow points to the bleeder screw (more about that later). Using a 14mm socket, remove the two caliper bolts.
These two bolts are the only thing holding on the caliper, so you should be able to pry it away from the rotor now. But before you do, make sure you have a length of wire nearby. It's important that the caliper does NOT hang freely, supported by the brake line. This will put stress on the brake line and may cause a hydraulic failure later on. So... gently but firmly pry the caliper away from the caliper bracket, slip the wire through the caliper bolt hole, and suspend the caliper from any convenient point. See photo at left. At this point, the old pads will either fall out, or they'll remain in position on the caliper bracket. Remove the pads (they'll slide right out) and examine them. The pad thickness should be at least 0.06" (1.6mm). This is for the pad alone and does NOT include the backing plate. If your pads are anywhere near this thickness (actually... thinness), then it's time for new pads. The set of new pads should come with a packet of brake lube. If not, you'll have to buy a small container at an auto parts store. Any brand of disc brake lube (also called caliper lube) will do. But before we install the new pads, let's remove and lubricate the caliper pins. Lubricating the Caliper Pins
Remove the two caliper pins (see photo at left). You'll have to pry the rubber boot away from the head of the pin. Once free of the boot, the pins will slide out. No tools are needed. Just grab the pins and pull them out. They're probably pretty yucky looking, so take a clean rag and wipe them clean. Then, using some of the brake lube that comes with the new pads, apply a generous amount of lube to the stems of each pin. You'll notice that the head of the pins are not round. There's a flat section on either side. Reinstall the pins so the flat sections are at top and bottom. Wipe off any excess lube that gets on the rubber boots. Now we're ready to install the new pads. Pushing Back the Piston
You've probably already noticed the difference between the old pads and the new ones—the new ones are a lot thicker than the old ones. So much thicker, in fact, that they just plain won't fit! That's because, as the old pads wear, the caliper piston extends into the caliper to maintain contact with the pads. (Disc brakes are inherently self-adjusting.) So, before installing the new pads, it'll be necessary to push the piston back into the caliper to accommodate the new, thicker pads. Keep in mind, though, that there's brake fluid on the other side of that piston. If you push the piston back in, the brake fluid has to go somewhere! In the old days, before ABS, you'd just take the top off the master cylinder and put a few rags under it. When you pushed the piston back in, the fluid would back up into the master cylinder, overflow, and the rags would catch it. But with the advent of ABS, things changed. Now, the recommended procedure is to clamp the brake line (so the fluid won't go back into the master cylinder) and open the bleeder screw so it can escape. The bleeder screw is shown in the first photo. There are special line clamps available for pinching off the brake lines, but you can use a pair of locking pliers if you pad the jaws to prevent damage to the lines. Don't over-tighten. NOTE: The bleeder screw may be corroded in place. Apply some penetrating oil and try to open it with a 10mm box end wrench (an open end wrench may slip and round off the bleeder). If it won't budge, try to tighten it just a little, and then try to loosen it. Tightening it may break its hold. If you alternate... tighten, loosen, tighten, loosen... eventually it'll come. But be careful. If the bleeder screw breaks off, you may have to get a new caliper! With the line clamped and the bleeder screw open, push the piston back into the caliper. To do this, use a C-clamp and small piece of wood as shown in the photo (above right). Here, a piece of plywood is placed over the piston and clamped tight. When the wood is flush with the surface of the caliper, the piston is back far enough to accommodate the new pads. The soft wood will prevent you from ruining the piston with the hard metal C-clamp. Once the piston has been retracted, tighten the bleed screw and remove the clamp from the brake line.
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