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Power Stop Brakes — FAQs

Power Stop

Power Stop answers these commonly asked questions.

If your question isn't answered here, please call one of our knowledgeable Brake Specialists at 1-888-344-4949.

See Power Stop Product Information for more product details.

See Power Stop Resources for "how to" info (install brakes, bleed brakes, break-in brakes) & warranty details.

See Power Stop Innovation & Research for rotor & pad technical data.

General FAQs

What is the best type of rotor or pad for my car?

You can also contact our knowledgeable Brake Specialists for assistance at 1-888-344-4949.

What is the best way to improve brake performance?

In order of effectiveness:

  1. Use good tires that grip the road
  2. Select brake pads with a high coefficient of friction for better pad bite
  3. Use cross-drilled rotors to improve convection heat transfer; to understand the types of heat transfer, see Power Stop Research's Drilled vs. Slotted Analysis

What is brake fade?

At high temperatures, all brake pads have a reduced coefficient of friction. This is called brake fade.

Pad bite is also called coefficient of friction. The higher the coefficient of friction, the more pad bite.

Power Stop engineers all of their friction compounds to resist brake fade. This assures safe, consistent stopping power.

Different grades of pads will have different fade characteristics. See Power Stop Research for benchmarking information that shows that Power Stop Evolution Ceramic Pads have significantly better pad bite and shorter stopping distance. The Power Stop Z36 Truck & Tow Brake Pads are by far the most fade resistant pad that is commercially available.

What causes brake noise?

All rotating objects have vibration. This vibration can become amplified at specific natural harmonic frequencies. Have you ever noticed a little vibration in your car as you travel at a certain speed on the highway then it goes away as you go a little faster? The wheels were passing through one of these harmonics.

Brake noise is caused by vibration primarily from the rotor, pad and caliper. The causes are complex and include things like the compressibility of the brake pad, the surface finish of the rotor, the stick-slip oscillation at certain temperatures, rotor dimensional run-out, rotor harmonic frequency and many other factors.

Noise attenuation is a complex part of friction development. Power Stop Evolution and Posi-Mold pads feature dual active rubber coated constrained layer shims. The rubber is placed on both the pad side and caliper side of the shim. This helps reduce vibration that can be transmitted from the pad to the vehicle.

Noise can be reduced by putting a silicon-based material on the back of the plate where the caliper piston makes contact. It is also important to turn the rotor and make sure the rotor flange is parallel to the hub mounting surface. Noise can occur if the pad overhangs the edge of the rotor or encroaches on the groove between the rotor hat and smooth flange surface. It is important that you check how the pad seats on the rotor when you change the brakes.

What brake fluid do you recommend?

Avoid using DOT 5.0 synthetic fluid unless specifically recommended by the vehicle manufacturer. Some synthetic fluids can cause rubber piston seals to break down. Power Stop recommends replacing brake fluid on every pad change with a DOT 3.0 or 4.0 fluid as specified in your owner's manual.

Rotor FAQs

What causes rotor warping (or pulsating brakes)?

The term warped rotors is commonly used to describe brake pulsation. The rotor is not actually warping at high temperature so the term warped rotors is not accurate.

The primary cause of brake pulsation is from uneven friction deposits on the rotor. As the brakes get hot, friction material from the pad is deposited as a very thin layer on the rotor. If you come to a hot stop and clamp your brakes down, the pad continues to deposit material on one spot. As you continue to use the brakes, this high spot on the rotor will get hotter than other parts of the rotor. When the temperature starts to exceed 1150°F, the crystal lattice structure of the iron can change into a very hard, brittle material called cementite. Your brakes can hit 1100°F or higher coming off a highway ramp with severe deceleration. Hard spots start to form and they do not wear down like the rest of the rotor. The hot spot nodules will not dissipate heat as well as the neighboring material, so it gets hotter than the rest of the rotor and causes the spot to grow. The result is a permanent high spot that you feel as pulsating brakes.

You can try to turn down the rotor but chances are the nodule is bigger than the cut depth on the lathe so it is just a matter of time before the pulsation will come back.

You can prevent brake pulsation two ways:

  1. Use a high-quality, properly-drilled rotor to keep the temperature low
  2. Don't clamp down on your brakes after a hot stop!

What is better: drilled or slotted rotors?

Power Stop makes cross-drilled only and slotted only rotors (in addition to a cross-drilled & slotted combo). There are distinct advantages to each.

Brake rotors can exceed 1000°F where many friction compounds start to break down. The high temperature can also lead to annoying brake pulsation and a shaking steering wheel.

Drilled rotors are engineered to keep your brakes cool, so your brake pad has improved pad bite with reduced fade. Drilled rotors can operate up to 200°F cooler to protect against rotor warping. This is why some high-end vehicles (such as Corvette, Porsche & Ferrari) come equipped with drilled rotors.

While a slotted rotor does a good job of removing gas and dust generated by the friction pad, it does not cool your brakes.

Improvement in brake output from drilled rotors is the subject of SAE Technical Paper 2006-01-0691 "The Effect of Rotor Crossdrilling on Brake Performance." In a nutshell, for street and highway driving, drilled rotors are typically preferred. For track, autocross, towing or other severe-duty applications, slotted rotors are recommended.

For more details on the advantages of each rotor style, visit Power Stop Research.

Can Power Stop rotors be turned down?

Power Stop does not recommend turning down the rotors. However, drilled or slotted rotors can be machined using a sharp bit and very light cuts (to prevent bit skipping near the holes). Under no circumstances should a rotor be turned below the hole chamfer depth.

What is better: painted rotors or zinc-plated rotors?

The purpose of painting or plating a rotor is to resist corrosion. Rotors can get hot, more than 1000°F. At these temperatures, paint will peel or burn off. Zinc-dichromate plating is more expensive but it lasts much longer and keeps the rotors looking new for a longer time.

Will the silver or gold zinc dichromate plating wear off?

The silver or gold zinc dichromate plating will be removed by brake pad contact so the area underneath the pad will be natural gray iron after the first few stops.

Pad FAQs

What is brake pad glazing?

Brake pads contain various metals and minerals that are bound together using a resin. At high temperature, this resin turns to liquid and can bleed out onto the rotor.

Glazing is dangerous because it prevents normal contact between the pad and the rotor so you lose pad bite. Glazing can also cause brake pulsation commonly perceived as "rotor warping" (see above FAQ "What causes rotor warping (or pulsating brakes)?".

Drilled rotors prevent pad glazing as reported in SAE Technical Paper 2006-01-0691 "The Effect of Rotor Crossdrilling on Brake Performance". This is one of the reasons why drilled rotors provide 12% to 37% more brake torque over stock rotors.

What does "Thermal Scorched" mean?

The term "Thermal Scorched" brake pads refers to the curing of the first millimeter of the brake pad material in an oven. This process actually simulates a professional high-speed break-in procedure used by professional mechanics and race teams. It heats the surface of the friction material to a very high temperature which cures the compound and makes sure it is 100% ready to perform.

This process makes the coefficient of friction consistent and predictable right out of the box. It also prevents pad glazing.

Many manufacturers do not go through this extra step but Power Stop knows the importance of proper break-in of new brake pads, so we make sure that they are thermal scorched during the production process.

How do I break in the pads?

When installing new rotors and pads, it is important to conclude installation with a break-in (or bedding) procedure. Proper pad bedding can prevent rotor warping.

The break-in procedure is critical to brake performance. It establishes an even layer of friction material on the rotors from the brake pads. It is very important that this initial layer of friction material be evenly distributed.

Power Stop provides detailed instructions on pad break-in in the Power Stop Resources section.