Pad Swapping

While swapping in a new set of pads in place of worn out old ones seems a pretty simple, it is a task to best taken very seriously. There is zero room for short cuts or monkeying around when working on brakes. A service manual is crucial. A misstep made or shortcut taken during brake assembly could have dire circumstances. The exact procedure for getting to and replacing the brake pads is as varied as the many different kinds of cars in the world. If the brake pad swap is not completely obvious, then peer into the manual to solve any mysteries. Always check the condition of the brake rotor before installing new pads. If the rotor isn't excessively scored and still measures above minimum thickness then all is well. Swap out the old brake pads for new. If the rotor is too thin or full of peaks and valleys, then replace or resurface the rotor first. Brakes are not a place to skimp or save money.

Friction Materials Convention

The next choice to be made in a brake pad replacement is brake pad material itself. There is no one friction material that works best in every situation. Brake pad material designed for everyday mototring will quickly overheat during performance driving, causing rapid wear and brake fade. Super high-performance or racing brake pad material will never get hot enough to create braking friction in everyday driving. Running with race-compound brake pads on the street will just make a lot of noise, and can actually be dangerous. A general rule is the more aggressive the brake pad material, the faster the rotor will wear out. More noise should also be expected as friction material ratchets up the performance scale.

Extra Crispy

Selecting the right brake pad material starts with honesty. If driving down to the corner store for snacks is the routine, than super-performance brake pads are not required. If track days or canyon runs are marked out on the calendar, then a performance compounds may hold the answer. Organic pad material features normal stopping power and wear along with low or zero noise. Next up in line are the metallic or semi-metallic pads. Genuine metal makes these pads more aggressive, but can bring more noise and disc wear along to the brake party. Semi-metallic pads can be considered an upgrade over organics. Ceramic compounds allegedly offer the best of both worlds, with superior stopping power and long wear along with low or no noise. Another bonus to ceramics is lower dusting, which can keep those fancy wheels cleaner longer. Similar to tire compounds, brake pad friction material is about compromise. There is no free lunch.

Make Your Bed and Stop in It

Like a new set of Chuck Taylors a new set brake pads should be broken in for best results. One method is to drive around and make 8-10 full stops at moderate speeds followed by a cool-down period. Select a boulevard with a good amount of stoplights but not a ton of traffic. After the eight or tenth stop, park the vehicle and allow the brakes to cool for around 20 minutes. Don't set the parking brake! Go grab a burger, or coney island. Repeat the procedure on the way back to home base. The stopping and starting will heat cycle the material in the pads. Bed-in recommendations vary by manufacturer. Super performance pads may require specific bed-in procedures unique to pad material. While not entirely necessary with some compounds, running a bed-in is a good way to make sure everything was put back in the right way.

Stuff You'll Need:

· Service Manual
· Jack and Jack Stands
· Brake Pads
· Brake Parts Cleaner, and lots of it
· Catch Tray
· Gloves and Safety Goggles
· Hand Tools
· Torque Wrench
· Brake Caliper Tool(s)
· Brake Caliper Grease
· Brake Fluid

Jack up the old heap and remove the wheels. Use brake cleaner to remove brake dust and road grime. Do not use compressed air. Do not breathe brake dust. Handy tip for those inclined to immediately tear everything apart. Leave one side assembled for reference. Forgetting how the various anti-rattle clips, shims, and gizmos go back together is wicked easy to do.

New brake pads should never be installed onto excessively worn rotors or into spent and corroded brake calipers. Measure the rotor minimum thickness with an outside micrometer. The cheap plastic ones work fine for brake rotors. If the rotor is too thin it will overheat and warp. It may already have. Check rotor run-out (warping) with a dial gauge. Replace rotor if numbers don't mesh with those in the manual, or the minimum thickness stamped onto the rotor.

Get the hammer if you find one of these holding on the rotor and acting the goat. A smack or two on the screwdriver may be enough to loosen it. Still stubborn? Use an impact screwdriver. Penetrating or rust busting oil may also play a role.

If caliper removal is required to replace the pads, never let the caliper hang by the brake hose. Use a length of bailing wire or rest the caliper somewhere that causes no stress on the brake hose. Remove old pads and note position of clips, shims, and tabs.

These old pads still had some meat on 'em but were glazed. Delicious and sugary glaze is great on donuts, but lousy for brake pads. Glazed brake pads suffer a loss in efficiency as they lose their ability to bite into the rotor and create friction.

Remove the brake fluid reservoir cap, and some of the brake fluid. As the brake pads wear they become thinner, and the brake caliper piston pushes outward. The space behind the caliper fills up with brake fluid. See the reason why some brake fluid needs to be removed in the next step. Danger! Brake fluid will destroy painted finishes.

To install the new and thicker pads onto the rotor, the caliper piston may need to be compressed back into the caliper with one of these fancy tools. This action will push brake fluid back up into the reservoir. Auto parts stores will rent you a box-o-brake tools on the cheap. An old brake pad or two, a screwdriver, and some leverage is another method. Clean off the caliper piston first, as not to send dirt back into the caliper. Brake cleaner!

These calipers had been on the car for a few presidents and needed some fresh grease on the caliper slider pins. If the manual calls for grease, use only high-temperature grease designed specifically for brakes. Regular grease will melt all over everything. Brakes get wicked hot. Glazing is for donuts.

Install new pads into caliper making sure all shims, anti-rattle clips, tabs, and gee-gaws are in the right place. Use brake cleaner to remove any greasy fingerprints and other contaminants from pad surfaces and rotor before mounting caliper on disc.

Mount caliper back on the on disc. Use a torque wrench to torque mounting bolts to specifications. Clean one last time with brake cleaner just for kicks. Depress brake pedal to seat caliper piston and pads. Spin the disc to make sure it spins. Check and add brake fluid if needed. Finish up the other side or other three, and then bleed the brakes.

Related:
Bleed the Brakes; And You Will Know Us by the Trail of Parts [Internal]

Hygroscopic Action!

As do brake pads and rotors, brake fluid wears out. A more accurate description is that the fluid becomes contaminated with moisture by nature of being hygroscopic, which by definition means it has a tendency to absorb moisture from the atmosphere. Water in brake fluid bad news on two levels. Brake fluid is made to resist turning from a liquid into a gas - or boiling. Water turns from liquid to gas at 212 degrees. If the brake fluid absorbs too much water, its boiling will drop. When the brakes get hot the brake fluid will boil, and turn from liquid to gas. Not a good deal at all. Boiling of the trapped moisture also creates the vapors within the brake system, and may be where the air in the lines came from in the first place. Classic symptoms of air in the lines is a spongy brake pedal feel. Another problem with contaminated brake fluid is corrosion. Water in the brake fluid makes it corrosive to every part of the brake system. Regular flushing of brake fluid by way of bleeding can keep corrosion and brake failure away.

Dotted Lines

When it comes to bleeding brakes and replacing brake fluid try to use new brake fluid with the same DOT rating as the stuff that's already in there. DOT is an acronym for the Department of Transportation. Brake fluid is classified as DOT3, 4, 5 and so on. What the DOT ratings specify is the minimum boiling point of the brake fluid. Be wary of using some DOT 5 silicon-based brake fluids. These fluids get around the problem of water absorption by being not at all hygroscopic. While this solves one problem it creates another. Any water in the brake system settles at the lowest point, such as the bottom of a brake caliper piston. An extremely important thing to remember about brake fluid is that is will destroy painted finishes. When working with brake fluid always keep plenty of cool, clean water nearby. Immediately flush any spills. Always dispose of used brake fluid properly. Over the years we've tried plenty of different ways to bleed brakes, but always come back to this simple hose and catch container riff. We're counting on you to share your favorite brake bleeding methods or stories in the comments.

Stuff You'll Need:

· Service Manual
· About Two Hours
· Penetrating Oil or Similar Potion
· Brake Fluid
· Vinyl Tubing
· Bleed-o-Matic or Similar Catch Container
· Line or Box-End Wrench, Hand Tools
· Plenty of Cool, Clean, Water for Spills
· Siphon or Turkey Baster
· Jack and Jack Stands
· Catch Tray
· Helper [Optional]

Locate the bleed screws and spray some penetrating oil or similar miracle rust busting potion onto the threads. These small screws are notoriously easy to shear off. Miracle fluid will help them on their way. A light tap with a small hammer can also help break the threads loose. Go easy there, Thor.

Siphon off as much of the old crappy fluid as possible. Brake fluid should be clear, not dark brown as shown here. Top off reservoir with new clean fluid to the full level. Don't let the master cylinder run dry while bleeding. Try to use fluid from a fresh bottle. Brake fluid is hygroscopic even sitting on a shelf in a container. If using the turkey baster, don't use it to baste turkeys or roasts again. Remember: brake fluid will destroy paint.

Start with the caliper or wheel cylinder furthest away from the master cylinder. First mount a wrench on the screw in question, and then slip a bit of tubing over the end. Use a line wrench or the box end to prevent stripping. The other end of the tubing goes into a catch container. We like to use cheap clear vinyl tubing from the hardware store, and one of these bleed-o-matic deals with the magnet on it.

Crack the bleeder screw just enough to let fluid and ideally trapped air to escape. The trick is not to turn it so far that the screw lets air back in. Gravity may take effect here. Be prepared for brake fluid.

Go back into the car and slowly push down on the brake pedal once or twice. If you have an assistant, then have them push down on the pedal. Now is also a good time to replace any worn pedal covers. Close the bleed screw. The bleed screws are just as east to shear off while tightening as loosening. Check the catch container, and add more brake fluid to the reservoir if required.

Pump the brake pedal a few times. Open the bleed screw again. Repeat the opening of the screw and pushing down of the brake pedal until the brake fluid runs clear and bubble free into the catch container. Cinch up the bleed screw, and move on to the next nearest bleeder screw. Keep going until the fluid runs clear and free of bubbles from all four.

ABS equipped systems may require an additional step. This is where the service manual for your own fine automobile comes in handy. This giant firewall mounted slug of aluminum und schteel is the rear ABS brake actuator on a 1987 Starion. YMMV.

Another plan is to pick up one of these power bleeder deals, or make one from a plant sprayer and associated hardware. The idea is to pressurize the entire system at once, then bleed without the whole climbing in and out of the car and pushing the pedal deal. – Mike Bumbeck

Related:
And You Will Know Us by the Trail of Parts [Internal]