Frequently Asked Questions

WHICH SIDE OF THE VEHICLE IS LEFT AND WHICH IS RIGHT?

When referring to the left and right side of a vehicle, it is from the perspective of one sitting in the driver’s seat. For vehicles in the US, the driver’s side is the left side, the passenger side is the right side.

HOW DO YOU CLEAN THE SHIPPING OIL OFF OF NEW ROTORS?

Centric Parts uses several different protective coatings. They can all be removed using warm soapy water or brake cleaner (or similar solvent that leaves no residue) if needed.

WHAT IS THE BED-IN PROCEDURE FOR NEW BRAKE PADS AND ROTORS?

Posi Quiet™ brake pads are scorched at the factory, and will bed-in during a normal post service road test. No special procedure is necessary.

I FEEL A STRANGE PULSATION UNDER BRAKING. ARE MY ROTORS WARPED?

Your rotors are not warped. The term “warped rotors” is frequently incorrectly used to explain the judder sometimes felt under braking, however, the iron used in rotors is almost impossible to physically warp because of its hardness and stability. Instead, the vibration is typically due to either an uneven transfer layer of friction material on the rotor face, corrosion resulting in an uneven surface condition, or by a prior unsuccessful machining of the rotor by a technician. A proper bed-in (see above) is essential to minimize the occurrence of this phenomenon.

A re-machining of the rotor surface might solve the problem temporarily, but it will likely return if there has been a conversion of the iron makeup below the deposit to cementite (also known as “hot spots”) - an iron-carbide. Cementite is harder than the base iron so when turned on a brake lathe, the harder deposit area will deflect the nose radius on the cutting tool and the high spot will still be present to a degree and the process of increasing deposit of new pad material over the high spot will re-start. Surface grinding of the rotor will produce a suitable result if the two friction surfaces are flat and parallel but there will still be areas of greater hardness.

DO I NEED TO REPLACE THE ROTORS WHEN I REPLACE THE PADS?

Rotors only need to be replaced if they are thinner than the allowable minimum thickness, if they are cracked, or if damage exists that cannot be repaired by properly resurfacing the brake rotor.

DO I NEED TO MACHINE THE ROTORS WHEN I REPLACE THE PADS?

If you are experiencing no brake vibrations/judder and there is no excessive grooving/wear in the brake rotors, they do not need to be machined. If a pulsation/judder condition is present, or if excessive grooving exists in the brake rotor, it may have to be either machined or replaced. Always make sure that after machining a brake rotor the rotor is safely above its minimum thickness specification.

MY BRAKE PADS MAKE NOISE UNDER BRAKING, WHAT CAN I DO?

The annoying high-pitched noise known as brake squeal is usually associated with some incorrect or inferior combination of friction materials. This type of brake noise can be reduced by the use of anti squeal plates. It can also be improved by the use of a different pad material, but also made worse if the former and current pad materials are incompatible. Other common causes of brake noise include worn pad and/or caliper hardware, surface contamination of the brake pads or brake rotors, and poor rotor surface condition.

DO I NEED TO BLEED MY BRAKES EVERY TIME I CHANGE THE PADS AND ROTORS?

While not absolutely necessary, properly bleeding the brakes after changing pads almost always results in a firmer, more responsive brake pedal and better performance. Always follow manufacturer recommendations regarding brake fluid changes.

I CAN'T GET MY BRAKES TO BLEED. WHAT AM I DOING WRONG?

Refer to your service manual. Different makes and models require different specific bleeding procedures. Some models require a scan tool to carry out this procedure. Additionally, if the calipers were replaced, make sure they were installed on the correct sides of the vehicle so that the bleeder valves are towards the top of the caliper.

HOW DO I BLEED MY CLUTCH HYDRAULICS WITH NO BLEEDER ON THE SLAVE CYLINDER?

Many modern clutch hydraulic systems are not equipped with bleeder valves on either the master cylinder or the slave cylinder. Always consult OE service information / technical bulletins to see if application specific bleeding procedures exist. Use the following procedure as a supplement to OE service information to bleed these types of systems when individual components are to be replaced. An assistant will be helpful in this procedure. If the slave cylinder is being replaced and the replacement part has plastic straps to retain the pushrod, DO NOT cut the straps, disconnect them for the bleeding procedure, and then reconnect them before installation into the bellhousing. The straps will break when the clutch pedal is depressed the first time.

Connect line between clutch master cylinder and slave cylinder, do not attach slave cylinder to transmission
Fill Clutch Master Cylinder reservoir with new, clean brake fluid from a sealed container
Holding the slave cylinder at an angle so that the line connection is at the highest point, manually compress the slave cylinder pushrod and release slowly
Have an assistant watch the fluid in the master cylinder reservoir. Air bubbles will rise through the reservoir as the slave cylinder is compressed. Repeat step 3 until no air bubbles can be seen rising through fluid in the reservoir
When no more air bubbles are present, all the air has been purged from the system and bleeding is complete. Reattach slave cylinder and check for proper operation

If your vehicle master cylinder is mounted to the firewall on an angle…

The master cylinder must be level in order for all the air to be properly bled from the hydraulic system. On some vehicles (ie: Ford and Chrysler SUVs) the clutch master cylinder is mounted on an angle, so that the end mounted to the firewall is positioned higher than the line connection to the slave cylinder. In cases like this, air will become trapped at the highest point in the system. To bleed these systems, the master cylinder must be leveled by either raising one end of the vehicle or disconnecting the master cylinder from the firewall and pedal linkage so that it can sit level while bleeding the system. Once the master cylinder is level, the above procedure can be used to bleed the hydraulic system. Reattach Master Cylinder to the firewall, reconnect pedal linkage, and check for proper operation.

WHY DO MY PADS WEAR UNEVENLY?

Uneven pad wear can occur for a variety of reasons. Minor cases of uneven or tapered wear can be normal, but more severe cases can be caused by:

Worn or sticking caliper slide pins
Worn caliper or pad hardware
Corrosion of the caliper/caliper bracket

WHY DO I NEED TO MEASURE RUNOUT WHEN INSTALLING A NEW ROTOR?

Almost every case of brake pulsation issues are due to uneven brake pad friction transfer to the surface of the rotor. This causes a Disc Thickness Variation which changes the distance between the pads at least twice per rotor revolution during a brake application.

This results in pressure surges feeding back to the master cylinder, and ultimately, an annoying pedal vibration or pulsation.

There are several very commonly overlooked steps that can eliminate almost all pulsation issues, one of which is measuring Installed Rotor Lateral Runout. It is important that when new rotors are installed or machined rotors reinstalled on a vehicle, a dial indicator is used to verify that the lateral runout is within factory specification for the particular model of vehicle.

WHY DO MY NEW/MACHINED ROTORS HAVE MEASURABLE RUNOUT WHEN INSTALLED ON THE HUB?

OEM maximum lateral runout specifications generally range anywhere from 0.0012” to 0.0025” measured 1/4” in from the outer diameter of the brake rotor. Obviously, ZERO is the ideal number, so regardless of the OEM maximum allowance for runout, the closer to ZERO, the better.

It is very rare to see a new rotor with more than 0.001” of runout out of the box. Most excessive runout conditions on floating or behind-the-hub rotor applications are due to either damaged or worn hubs, lack of cleanliness of the hub and rotor mating surfaces, or uneven/improper wheel fastener torque.

WHY DO SOME EUROPEAN OE BRAKES PRODUCE BLACK DUST?

European brake systems are intentionally designed using relatively abrasive friction material with relatively soft, “high carbon” or “dampened iron” brake rotors. While this system offers excellent performance and low noise, the majority of the dust seen is caused by the pad wearing the rotor.

WILL MY CENTRIC PARTS BRAKE ROTORS RUST?

Brake Rotors are made of cast iron, which will oxidize/corrode/rust if exposed to caustic chemicals or moisture. At Centric Parts, they have taken measures to limit the exposure of the iron rotor by utilizing a unique e-coating on premium brake rotors. E-coating is an Electrocoating finish applied to all surfaces not swept by the brake pads.

While this coating does an excellent job of protecting the surfaces underneath it, it cannot protect the friction surfaces, or swept surfaces of the brake rotor. Centric Parts leaves the friction surfaces, or swept surfaces, uncoated because brake pads require an interface with a plain cast iron surface to operate correctly. Some manufactures sell rotors that are plated or coated in their entirety, which looks attractive before installation, but that coating will very quickly wear from the friction surfaces resulting in a rotor friction surface exposed to the elements and subject to corrosion/oxidation/rust. In addition, any coating on a new rotor friction surface can contaminate the brake pad during initial pad break-in, resulting in noise and performance issues.

If the brake rotors are used in a corrosive environments (i.e. where caustic road de-icers are used), rinsing the brake system as often as is practical with water will help keep the friction surfaces free from excessive corrosion.