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Brake Pads and Fluid Basics - Brake Check

How not to end up with the wrong pads for your whip

Aaron Bonk
Jan 16, 2017

One of the most important things going on with that hooptie of yours happens in between its brake pads and its rotors. It's there where a specific amount of friction determines whether or not you'll be able to do things like make it around the Nurburgring's Adenauer Forst in your dreams or just keep yourself from plowing into the back of the Chrysler in front of you on the 405. But neither of those'll happen if you fail to do three things: choose the right brake pads for the sort of driving you do, install them and break them in the right way.

Brake pads and fluid basics brake rotor and caliper Photo 2/12   |   Those rotors, calipers, and pads behind whatever fancy rims you've got are some of your car's most critical bits. It's there where friction determines whether or not you'll be able to do important things like stop and not pounce into the van in front of you.

BUT FIRST, THE BASICS

You not plowing into the back of that Chrysler starts with your brake pedal and ends with its pads, but that's not the whole story. Stomp on that pedal and that brake master cylinder starts pushing fluid throughout all of those lines connecting to your calipers, drums, or ABS pump, moving things like pistons that allow your calipers to squash those pads against their rotors, which, when all goes right, introduces a whole lot of friction and stops those wheels and tires from spinning. A lot goes into a proper brake system, but no place else can such dramatic changes be made with such little effort and with such little dough than with its pads.

Brake pads and fluid basics braking system Photo 3/12   |   There are all sorts of components that make up your brake system, but dollar for dollar, there's no place you'll find a more dramatic change in stopping power than with the right pads.

HOW TO CHOOSE THE RIGHT PADS AND WHY YOU (PROBABLY) DON'T NEED RACE PADS

There are all sorts of brake pad compounds for you to choose from and, like that oversized turbo you've lobbed into your engine bay to compensate for whatever physical shortcomings you may have got, you're tempted to slap on those race-only pads. But like that turbo that barely spools, those race-only pads are doing more harm than good. Things like friction potential, heat dissipation, longevity, noise, and all sorts of other factors differ between various pads and are all things you ought to be concerned about before settling on anything.

Brake pads and fluid basics pads Photo 4/12   |   You ending up with the wrong pads is easy if you don't do your homework. You think that track-only compound is what you need for your street car and you couldn't be more wrong. Although pads designed for the track will outperform almost any street pads, they won't perform nearly as well as they ought to if they aren't able to get hot enough, which they never will on the street.

So before laying down the Benjamins for those new pads, why not consider these four things?:

  • What in the heck will you be using your car for? Hot laps at Buttonwillow or posting up at car meets looking for Instagram fame? Answer that question and you'll have an idea how hot those pads might get and what sort of friction capabilities you're going to need. Driving to that meet you can expect those pads to reach upward of 500 degrees F; temperatures on the race track can be twice that high. Every pad's designed to yield a certain amount of friction at a particular temperature; get the wrong ones and you can forget about stopping as good as you'd hoped.
  • How important is brake pad longevity to you? Hopefully not as important as performance, but let's throw it into the mix anyways.
  • What about brake dust? If you're a real Nancy, that sort of thing just might bother you, so let's add that to the list, too.
  • Finally, know when to go back to the drawing board; if you're experiencing brake fading on the track even after you've slapped on what you thought were the right pads, know that pads capable of higher temperatures might be necessary.

Street: You'll want a relatively soft compound here, mostly because you won't be applying the brakes as often as you would at, say, Laguna Seca, which means you need them to be ready to handle sudden stops even when they're cool. Go too hard and a panic stop on cold pads could cover 25 percent more ground. Wilwood's ProMatrix pads are about the best compromise between something that'll work as well on the street as it will on the track. The pads' dual-sport performance compound means you can have quiet, street-friendly pads that yield minimal dust but are still capable of the hotter temperatures you'll encounter when you do make it to the track.

Road racing: Harder pads are ideal here since you'll be on the brakes repeatedly. Go too soft and you'll experience brake fading in a hurry. Wilwood's PolyMatrix compounds are the company's highest-friction formula and are able to withstand severe temperatures for sustained periods of time, just like you'd experience on the track.

Autocross: You'll be on the brakes hard here but not as often, which means compounds somewhere in between what you'd use for the street and what you'd use for the road course are what you want. Wilwood's PolyMatrix pads can work well here too, but look to one of the line's softer compounds, like PolyMatrix E pads that are most effective at slightly lower temperatures.

Drag racing: Those pads you used on your street car, turns out you won't need something a whole lot different for your drag car since they've also got to perform suddenly and when cold. Wilwood's ProMatrix pads can work here but, chances are, you won't need that much bite. Look to the company's lower-friction and lower-temperature SmartPad BP-20 pads that are capable of providing aggressive braking even when they aren't subjected to a whole lot of prolonged heat, like with drag racing.

Brake pads and fluid basics wilwood brake pads Photo 5/12   |   Wilwood offers all sorts of brake pads designed for just about every level of motorsports to something suitable for your aunt's sedan. You visiting their website before you shell out for the race pads you think you need is the first step toward you making your car stop better.

INSTALL TIPS AND TRICKS

You learning how to slap on a set of brake pads happened sometime after you did your first oil change and slurried your parents' driveway with 10W-30. But that doesn't mean you've been doing everything right.

  • Don't be a bozo and let that brake caliper hang in mid-air. If you've got to remove it from the rotor instead of just swinging it out of the way, take the slack off its rubber hose by securing it with zip ties to a control arm or shock.
  • Chances are, whatever you drive's got sliding calipers up front where a single piston on one side pushes both pads against the rotor. Dab some grease on those caliper pins to keep the whole thing sliding like it ought to and applying equal pressure onto both pads.
  • Before you go barreling out of your driveway after you've finished manhandling those pads into place, press down on that brake pedal a few times to displace all of that hydraulic fluid into the right places. If you don't, those calipers won't be able to squeeze those pads against those rotors until after you've already toppled over your parents' mailbox.
  • Don't bother topping off that brake fluid reservoir until after you've monkeyed those new pads into place. The new and thicker pads will displace some of that fluid back into the system's lines and reservoir.

Brake pads and fluid basics unsecured brake caliper Photo 6/12   |   Letting that brake caliper dangle in mid-air is one of the quickest ways to spring a leak in that hydraulic brake hose. If you need to remove the caliper completely rather than just swinging it out of the way, secure it someplace using a handful of zip ties.
Brake pads and fluid basics greased calipers Photo 7/12   |   Your car's sliding calipers slip across a series of pins so that equal pressure can be applied to both sides of the rotor even as the pads wear down. You applying a dab of grease onto those pins when installing those new pads will never be a bad idea.
Brake pads and fluid basics brake fluid reservoir Photo 8/12   |   As brake pads thin down, the fluid level in the brake fluid reservoir drops. Once the pads are replaced, the level rises again. Be sure to check the fluid level after the pads have been installed and pedal pressure's been applied.

TURNS OUT THERE'S A RIGHT WAY TO BREAK IN THOSE BRAKES

You've finished installing those pads and dropped your whip back on the ground but you aren't finished. If you want those new pads to work how they ought to, you've got to break them in. Put them to task right away and you're asking for premature wear and possible rotor damage. According to Wilwood's Michael Scully, the whole idea is to get a layer of the pads' material transferred over to those rotors. Here's how to do it right:

  • First make sure you knew what you were doing when you installed those pads. The brake pedal should remain firm, even after applying pressure for several minutes, and your car ought to stop like normal and without any brake-related noise or leaks.
  • Get up to speed and then lightly decelerate several times to heat up those pads. Apply the brakes for a few seconds at a time and then lay off for twice as long. This'll allow all of that heat to sink into those pads and rotors.
  • Do the same thing only this time apply even more pressure to that brake pedal to generate even more heat.
  • And again, this time with even more pressure and from roughly 60 mph down to about 25 mph. Don't forget to allow the brakes to cool in between braking periods for roughly twice the amount of time that your foot was on the pedal. If you experience any brake fading, let off the pedal and start the cool-down cycle.
  • Now cruising, allow the brakes to thoroughly cool down by using them as minimally as possible. Finish up by pulling over, parking, and allowing those pads to cool down to the touch.

Brake pads and fluid basics bedded brake pads Photo 9/12   |   Properly bedding in new brake pads is critical. Do it wrong and you'll experience faster rotor wear and you'll never know just how well those high-performance pads could've worked.

PAD PRO TIPS

SS: What's your best piece advice for someone who insists on using track pads on his daily driver?

Michael Scully, Wilwood: Budget-friendly, get two sets of pads-one for the track and the other for the street. Open budget, get one set of pads and rotors for the street and one set of pads and rotors for the track.

Brendan Cashman, EBC Brakes: Obtain the friction coefficient data from several brake companies to determine which is the best choice. Many track pads lack a decent cold bite and require heat to work, which isn't ideal for street use.

Yoshi Iizuka, Project Mu: Be prepared for noise, brake dust, and reduced bite until the pad reaches normal operating temps.

SS: What's a common mistake you see with bedding in new pads?

Michael Scully, Wilwood: You have to get the brake system really hot. If you never get the brakes hot enough to smell (like they're burning), you haven't properly bedded them in. That makes a huge difference.

Brendan Cashman, EBC Brakes: When an aftermarket part is installed, people want to immediately test it out; how much better than stock will the new part be? It will, unfortunately, take a considerable amount of time to see the benefits of aftermarket brake pads. A few hundred miles of careful braking will allow any unsettled resins to burn off and the pads to bed flat against the rotors.

Yoshi Iizuka, Project Mu: The time and speeds that are needed to properly bed in pads. We don't suggest bedding on public roads, and bedding on the track will eat up a session. Another option is pre-bedding, which is a service Project Mu can offer.

SS: Any brake pad installation tips or common install mistakes that you suggest avoiding?

Michael Scully, Wilwood: Make sure the friction material is on the correct side of the rotor. We've seen numerous tech pictures of pads put in backwards where the backing plate was installed against the face of the rotor.

Yoshi Iizuka, Project Mu: Pump the brake pedal after changing pads and before driving. More people than you think forget to do this.

Brake pads and fluid basics improperly installed brake pad Photo 10/12   |   Wilwood's Michael Scully says there are all sorts of ways you can bungle up your brake pad installation, one of which he says is all too common is to install the pads backwards. For obvious reasons, be sure that the pad's friction surface faces its rotor.

DOT WUT!?

You already know that some sort of hydraulic fluid is the lifeblood of your brake system. But what you don't know is what sort of fluid you need, how often it ought to be changed, and if spending money on the expensive stuff is even worth it.

DOT breakdown: The U.S. DOT (Department of Transportation) classifies brake fluid into three kinds: DOT 3, DOT 4, and DOT 5. But don't assume that DOT 5 is best for you just because you like bigger numbers. DOT 5 fluid is silicon-based-not glycol-based like the others-and isn't able to withstand high temperatures. That leaves you with DOT 3, which is what your car probably has in it now, and DOT 4, which'll cost you more but absorbs less water and is able to withstand more heat.

Brake pads and fluid basics dot 3 brake fluid Photo 11/12   |   Chances are, your brake system's made up of DOT 3 fluid. For race cars or applications where excess heat is a factor, consider switching to DOT 4. It's more expensive but can mean the difference between your brakes working or not.

Knowing when to flush: Fresh brake fluid won't make a crappy brake system better but it will determine whether or not your brakes work as well as they should. EBC Brakes' Brendan Cashman says to flush things out every 12-24 months to keep things working smoothly. That's more frequent than what the engineers who made your car will tell you, but you don't drive like how the engineers who made your car think you do. Even small amounts of water that gets absorbed over time can result in a lower boiling point and total brake failure. For track cars, Project Mu's Yoshi Iizuka says to do so even more frequently: "A proper fluid flush is recommended just before and after a visit to the track. Clean fluid free from air is vital to a healthy brake system."

Picking the right fluid: Just like you winding up with the wrong pads, you using the wrong fluid isn't impossible. Scully says that in most cases DOT 3 is just fine, but if you've got a dedicated track car or spend a significant amount of time racing, then you ought to consider DOT 4 because of its higher boiling point.

Brake pads and fluid basics project mu dot 4 g four 335 brake fluid Photo 12/12   |   Project Mu's DOT 4 G-four 335 brake fluid can withstand temperatures hotter than you'll ever experience and changes color to let you know when it's time to flush it all out.

THE HEEL-TOE SHIFT AND YOUR BRAKES

If you're a weenie, you might argue that in order to do a proper heel-toe downshift you just might be subjecting those brake pads to a little extra wear and tear. The approach allows drivers to brake later and, by default, harder. How you ought to perform the heel-toe shift won't change, though, whether or not you think it'll burn those pads down any faster than normal or not. Do it right and it will, however, get you around the track just a little bit quicker.

  • Brake for the corner using your right foot positioned at an angle pointing slightly toward the gas pedal.
  • Step on the clutch pedal using your left foot.
  • Here's where you'll mess up: With your right foot still on the brakes, roll its outside edge outward and down to engage the gas pedal and blip it. Do it right and you've just raised engine speed enough to match wheel speed. Also, you won't get this part right the first time around.
  • Move the shift lever into whatever gear's next.
  • Release the clutch pedal and start planning for the next turn.

Sources

EBC Brakes
Las Vegas, NV 89120
702-826-2400
http://www.ebcbrakes.com
Wilwood Brakes
Camarillo, CA 93012
805-388-1188
http://www.wilwood.com
By Aaron Bonk
343 Articles

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