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    Choosing the correct brake pad starts with an honest assessment of the driver's typical driving conditions.  For example, if the vehicle is driven 80 percent in highway and 20 percent sporty and zero percent on the track, then an Alcon "street" pad will likely offer the best combination of stopping performance, low dust and low noise.

    If the vehicle is frequently used for track days but also as a daily driver, it might be better served by the a mid-range racing pad - provided that an even transfer layer of pad material on the rotor is maintained by periodically re-bedding in the pads.




    Understanding your brake pad wear patters is important to diagnosing the general condition of your brake system.  This guide can help you identify common issues.

    Inboard or Outboard side uneven wear

    Brake Pad Outer Wear

    One pad has significantly less friction material than the other pad.

    This happens when the caliper piston is not returning to the rest position due to a worn seal, damage, or corrosion. Inspect caliper for residual pressure and guide pins or piston boot damage, respectively.  Wear like this is caused by the pad continuing to ride on the rotor after the caliper releases. Pads catching on the guide pins or the pistons not retracting (bad seals or damaged pistons)  Service or replace the guide pins, seals, or the entire caliper, and replace the brake pads.

    Tapered Pad WearBrake Pad Tapered Wear

    The friction material is worn in a horizontal or vertical wedge pattern.

    This kind of wear is caused by improper pad installation, bad seals on one piston,  or retention pin catching. The procedure for correcting this kind of wear is the same as correcting side to side pad wear.

    Cracking, Glazing, or Lifted Edges on the Pads

    The friction material is physically damaged and shows signs of thermal distress.

    Brake Pad Glazed Wear

    This can be caused by many things. Overuse, improper break-in procedure, hydraulic system problems, seized caliper components, defective pads, and the parking brake not fully retracting are some common problems. This can be corrected by replacing and breaking-in the new pads properly. The parking brake may also need adjusting.

    Overlapping Friction MaterialBrake Pad Overlapping Wear

    The top edge of the pad overlaps the top of the rotor.

    This can be caused by wear on the guide pins, caliper or caliper bracket or having the wrong rotor or pad on the vehicle. To correct this kind of wear, replace the pads and fit the vehicle with OE specification diameter rotors.



    The typical situation: New pads are fitted to a new pair of brake discs. A week later there’s a vibration or “judder” when the brakes are applied. A call to a mechanically inclined friend and an online search offers the diagnosis—the brake rotors are warped.

    Feeling some shudder in the steering wheel when applying the brakes? Conventional wisdom says that the rotors are warped, but really you might have a problem with friction material transfer. Don't worry, though, as the fix is relatively simple.

    The diagnosis may be further verified by measuring the surface of the discs to see if they vary in thickness. Some customers have the discs turned on a brake lathe to remove the high spots. That stops the vibration, apparently proving that the discs were warped. Except that the symptoms come back in a couple of weeks.

    Now the frustrated and disappointed customer calls Moss Technical Services or simply returns the brake discs as defective.

    The fact is: The discs were never warped at all. Every warped brake disc that we’ve investigated with the assistance of our suppliers shows uneven patches of friction material from the brake pads on the surface of the disc. These patches cause variation in thickness (run-out) and the vibration under braking. Brake manufacturers have been struggling to deal with this situation for years because warped discs are so readily blamed for brake-related vibrations.

    To understand what’s taking place, let’s look at what happens when we step on the brake pedal. The pads press against the surface of the disc, converting the energy of motion into the energy of heat through friction. What you may not know is that there are two kinds of friction at work: abrasive and adherent.

    Abrasive Friction: According to Carroll Smith, author of “The Warped Brake Disc and Other Myths of the Braking System,” abrasive friction involves breaking the crystalline bonds of both the pad material and the cast iron of the disc. Breaking these bonds generates the heat of friction. In abrasive friction, the bonds between the crystals of the pad material (and to a lesser extent, the disc material) are permanently broken. The harder material wears the softer away, meaning the disc wears the pad. When we see the word friction, it is abrasive friction that comes to mind.

    Adherent Friction: When brake pads press against the surface of the steel disc, some of the pad material transfers directly to the surface of the disc forming a thin, uniform layer. The surface of the steel disc and the surface of the brake pad become identical in composition. As the disc moves between the pads, friction material transfers in both directions, breaking and reforming bonds at the molecular level. This transfer of material in both directions is a normal and essential part of braking friction.

    Running the right brake pads and properly bedding them in will often cure any shudder. This can easily be an afternoon project.

    Pad Material: Brake pads all use a combination of abrasive and adherent friction during braking. Pad material differs based on the manufacturer’s specifications, which are always attempting to balance performance, wear, noise, and to a lesser extent, dust. There must be enough abrasive elements to keep the disc surface clean, and the pads must provide uniform adherent friction material transfer to the disc within the intended temperature range.

    Uneven Friction Material Transfer: Pads that are used beyond their intended temperature range will cause problems. Pads can be heated to the point where they transfer friction material to the disc in random, uneven patches. The thick and thin layers are not generally visible, but the driver can feel vibration and measure it with a dial indicator. Modern brake pads are engineered with the best possible combination of features, but they are still limited to their intended range of operating temperatures.

    Pad Selection: Generally, there are street, performance and racing brake pads, and most quality pads have broader temperatureranges than pads made 10 years ago. However, no street pads are suitable for racing, and no racing pads are suitable for the street. Performance street pads are a compromise—they’re more effective at low temperatures than racing pads and they can operate at higher temperatures than street pads.

    Where to Start: If you have vibration under braking with new discs and pads, first eliminate the obvious by making sure that the hub and wheel flange are flat, clean, and rust free. A miniscule amount of run-out here will be magnified at the edge of the brake disc. Verify that disc mounting hardware is in good condition, installed correctly, and tightened in the correct order according to the recommended torque specification.

    Bedding-In Your Brakes
    When new pads and brake discs are fitted, the most important thing you can do to prevent problems is to properly bed the brakes. This critical step is the initial transfer of friction material from the pad to the disc forming a smooth, uniform layer. It establishes a foundation that’s essential for proper brake performance. It minimizes the chance of laying down uneven, random patches of friction material which will be felt as vibration when the brakes are applied.
    All high-performance discs and pads should come with installation and break-in instructions. The procedures are similar for all major manufacturers.
    Since you don’t come to a complete stop during pad or disc break-in, you have to plan where and when you do this procedure for safety purposes. If you come to a complete stop before the break-in process is completed, there is a chance that nonuniform pad material transfer or pad imprinting will take place, resulting in an irritating vibration during braking.

    Basic Bed-In Procedure
    1. After installing new disc rotors and/or brake pads, perform eight to 10 slowdowns applying moderate pressure from about 30 to 40 mph (50 to 60 kph) without coming to a stop.
    2. Make an additional two or three slowdowns applying heavy pressure from about 40 to 45 mph (60 to 70 kph) without coming to a stop.
    4. Allow at least 15 minutes for the brake system to cool down.
    5. While the car is at rest during cool-down, DO NOT APPLY THE BRAKES. If you do, material will transfer from the pads to the rotor and probably give you braking vibration.

    After Brakes Are Bedded-In

    Slotted rotors reduce brake fade and pad material build-up on the rotor surface.




    At this point, your new disc rotors and/or pads are ready for normal use with a thin, uniform coating of friction material on the rotors. But the full process of building up the friction layer can take 190 to 300 miles (300 to 500 kms) depending on your driving style. There are two situations you should try to avoid during that time, as they can ruin that fragile friction coating, requiring another round of bedding-in.
    First, if you drive gently over a period of time with little heavy braking, you can actually strip off the necessary thin layer of friction material on the surface of the disc. This makes your brakes vulnerable to problems again. You can restore it by repeating the bedding-in procedure.
    Second, if you have an incident where you are driving at high speed and have to brake hard coming to a complete stop with your foot on the brake pedal, the pads will imprint on the disc surface, transferring what seems like a hunk of friction material. This uneven material will cause vibration.
    You can generally get rid of the excess material with abrasive friction by repeating the bedding-in process. If it’s a bad imprint and you can’t get rid of it this way, take your car to a shop with an on-car brake lathe. This process returns the discs to dead flat and then you can re-bed.
    So bedding-in may not be a one-time deal, but it will work with patience. If you continue to have trouble, contact Moss Technical Services.

  • Why Do Brake Rotors Warp?

    Warped Rotors

    Brake rotors are the large metal discs visible behind the wheels of a car. These spin along with the wheels so that when the brake pads clamp down on them, they stop the car. Brake discs have to withstand a tremendous amount of heat. Not only that, they have to dissipate that heat into the air as quickly as possible because the brakes will probably be pressed down again in a short amount time. If the surface of the disc becomes uneven over time, braking will become jittery and less effective. This is usually referred to as warping.

    How brake rotors warp

    A common misconception when rotors are referred to as “warped” is that they are no longer straight when rotating (similar to how a bicycle wheel gets warped). For cars, in order for that to be the case, the rotors themselves would have to be defective as the temperature required to make metal that resilient soft enough to simply bend would be tremendous.

    Instead, the warping really refers to the flat surface of the rotor becoming uneven. Heat is the number one cause of this, and can cause warping in more than one way:

    • Glazing the brake rotor with material from the brake pad. This happens because brake pads, like tires, are made with different amounts of hardness and stickiness depending on the intended purpose. When brake pads made for normal road use get very hot from high-speed driving and braking, or from riding on the brakes for a prolonged period of time, the grippy material can get too soft and basically "paint" the brake rotors. This means that the brake pads won't grip onto metal when the brakes are applied once again, causing decreased brake performance that is less smooth than before.
    • Wearing down the surface of the rotor and making harder spots in the metal stay slightly raised off the surface. The reason that brakes don't normally wear down very much revolves around a fairly straightforward concept. Since the metal of the rotor is harder than the brake pad applying friction to it, the pad wears down while the rotor remains largely unaffected. With excessive heat, the metal becomes soft enough for the pad to wear down the rotor surface. This means that slightly less dense spots in the metal wear down faster and make the harder spots stick out, causing warping.

    How to prevent warped brake rotors

    To prevent the brake rotors from becoming glazed over with brake pad material, be mindful of how much braking the vehicle is doing compared to what is done during normal operation. When going downhill for prolonged amounts of time, try to control the speed of the vehicle by shifting the transmission into a lower gear. For automatics, the only option is usually to shift into "3," while vehicles with a manual or other shiftable transmission can decide on the best gear to use based on the engine's revs. When the brakes are hot, never sit with the brake pedal hard down on one spot.

    Also, when the brake pads are first installed they should be properly broken in to ensure they don't leave too much material on the brake rotor. This usually involves getting the car up to road speed and then braking until it is traveling ten miles per hour slower. After this is done a few times, you can work your way up to braking to a complete stop. The first few full stops after that should be done with care. This allows the brake pad to perform better during hard braking further down the road.

    The steps that can be taken to prevent excess wear on the surface of the brake rotor are similar to the steps for avoiding glazed rotors. Be sure to avoid hard braking when the brake rotors have gotten hot from prolonged use.

    What do warped rotors feel like?

    There are a few symptoms to look for when it comes to diagnosing warped rotors:

    • If the brake rotors are glazed over, you may hear excessive squeaking when the brakes are applied or even smell burning rubber.
    • If the braking suddenly becomes jittery and inconsistent, the brake rotors should be the first suspect.
    • If the vehicle vibrates when coming to a stop, the brake rotor is likely warped.
  • Warped Rotors: Why Does My Car Shake When I Hit the Brakes?

    Warped Rotors and Brake Vibration

    If you're wondering why your car shakes when you hit your brakes, you more than likely have one or more warped rotors behind your wheels.

    What Is a Rotor?

    A rotor is the round piece of steel pictured below that your brake pads grab hold of when you hit the brakes. Depending on your hubcaps, you can usually see your rotors on the inside on the wheel.

    When a rotor comes out of the factory, it's smooth and even. When the brake pads make contact with both sides of the rotor evenly, smooth braking results. But what happens over time is that the rotors can become warped, meaning that they lose their smooth, even surface. When that happens, every time you go to hit your brakes, the brake pad encounters a surface that isn't entirely smooth, and the braking gets very bumpy.

    When you have warped rotors, they lose their sleek, smooth, and even surface for braking, which causes your car to shake.
    When you have warped rotors, they lose their sleek, smooth, and even surface for braking, which causes your car to shake.

    What Causes Warped Rotors?

    Warped rotors can be caused by multiple things. Here are a few common reasons:

    1. Sudden braking: As you're driving along, if you ever are forced to brake suddenly from a high speed, the friction can cause a level of heat on the rotor great enough to cause the rotor to warp.
    2. Constant braking: If you're ever driving down a long hill and are constantly having to keep your foot on the brake, the buildup in heat can also cause the rotor to become warped.
    3. Overuse of brake pads: Another thing I've experienced that has caused rotor damage has been excessive use of brake pads, meaning that the brake pads weren't changed early enough and partial metal on metal friction was allowed to happen. I've replaced rotors before that have had such deep grooves that you could literally put a marble in them and spin it all around the rotor. You don't want that to happen to your vehicle.

    What You Can Do

    When your rotors get warped and your car shakes when you hit the brakes, you have a couple of options.

    If you change your own brakes, it will be a lot less expensive to fix the problem than if you take your car to the shop for brake jobs. If you've been experiencing some shaking when you hit the brakes and you're due for a brake change, then that's the perfect time to deal with your warped rotors. If the rotors are fairly new then you may not need to replace them. You can take them off and drive them down to your local auto parts store and have them turned on a special machine that grinds down the outer warped layer of the metal to make the surface smooth and even again. But there are two things that you need to be warned of when considering this process.

    1. If your rotor is too thin the auto parts store won't grind them down for you and you'll have to buy new ones. This isn't really all that much of a problem since new rotors are generally only about $40 a piece.
    2. Make sure you call ahead to schedule a rotor turning appointment. Sometimes when auto parts stores are swamped, it may take a while to service your rotors and you'll end up sitting there for a long time. The process shouldn't take more than 30 minutes or so per rotor, but if the shop is busy, it's just best to call ahead and make sure they can do it quickly for you.

    Each auto parts store will probably have a different cost for turning your rotors, but it shouldn't be more than $25 or so. So all in all, changing your brakes yourself and having your rotors serviced should cost you less than $100, which is pretty nice.

    If you don't service your brakes yourself but take them into the mechanic, tell your mechanic that your rotors are warped and that you want him to turn them for you. Ask him how much it costs for the process and hold him to it.

    Another thing you can do is to go to the auto parts store before you go to the mechanic and buy a set of rotors from the store and then ask the mechanic to replace your rotors when he does the brake job. It should only be a matter of loosening a couple bolts, so don't let him charge you an arm and a leg for the labour.

    Best of luck!

  • Stop the ‘Warped’ Rotors Myth and Service Brakes the Right Way

    brake rotor runout

    Myths take hold ­because either A) they seem completely logical or B) they are so often repeated that they just become common knowledge. The warped rotor myth is a little bit of both. A rotor that contributed to a pulsation condition certainly appears “warped.” Plus, everyone says it — even technicians that know the rotor isn’t ­really warped will say it as shorthand.

    Rotors are cast in extreme heat — three to five times greater than the most aggressive braking situation. Physically “warping” a rotor would require a similar application of extreme heat, which is impossible.

    Obviously rotors aren’t invincible. They can crack, break and develop irregularities that lead to pulsation, but all of those problems start to develop in other ways that need a technician’s touch.

    Starting today, remove “warped rotor” from your vocabulary. Instead, you should be both looking for and educating your customers about these terms:

    Rotor runoutLateral runout

    Runout is a measurement of the difference between the high and low spots in the hub and on the rotor.

    On each revolution of the wheel, as the high spot of the rotor scrapes unevenly with the hub or applies friction unevenly with the pad, the results for the rotor’s face are just that — uneven.

    Root causes of runout include:

    • Runout from the hub mounting face;
    • Runout from the wheel bearing;
    • Sloppy resurfacing/machining procedures;
    • A buildup of rust and corrosion between the rotor, hub and wheel;
    • Uneven torque on the lug nuts;
    • Wheel loading distortions; and
    • Variations in manufacturing tolerances.

    Other vehicle components can exacerbate the problems with runout. For example, if a vehicle’s floating or sliding calipers aren’t sliding as they should, that will prevent the caliper housing from moving, and any runout can cause pulsation. The caliper piston will move in and out as the rotor rotates resulting in fluid movement and pedal pulsation.

    Fixed-caliper vehicles are sensitive to runout induced pedal pulsations as well. Fixed calipers have pistons on both sides of the rotor due to the stationary caliper housing. Excessive runout will cause piston movement and can result in pedal pulsation.

    New: Over the past 30 years, factory runout specification have fallen from as high as .015″ to .000″ (or no detectable runout) for some vehicles. These tightening of the tolerances is due to changes in suspension design, friction formulations and caliper designs. When runout moves beyond specification set by the manufacturer, the uneven application against the pad will lead to disc thickness variation.

    warped rotorsDisc Thickness Variation

    This is the real culprit behind most of your “warped rotor” claims. A normal braking event requires a brake pad to be applied squarely against the rotor. Each time this happens, a tiny layer of friction is removed from the pad and is deposited on the face of the rotor.

    A rotor with runout beyond the specs cannot receive that even application of friction, which means it starts to receive an uneven deposit of friction on its surface. Disc thickness variation is just that — the rotor is now thicker in some spots thanks to the extra layers of friction, which all started because of lateral runout. The DTV is the thickest area minus the thinnest area of the rotor.

    The thickness variation is subtle, but all of these details add up. When the thick part of the rotor is forcing itself through the caliper, the torque of the brake and the pressure in the caliper rise. When the thin spot passes through, the torque drops and pressure drops. Very small amounts of DTV can create a significant problem. More late-model vehicles are built with a thickness variation of less than 0.00078”. Thickness variations in excess of 15 microns (0.00059”) can easily generate driver complaints.

    Factors to take into account:

    • The suspension. Unibody vehicles with strut suspensions are more sensitive than those with a separate frame and body.
    • Wheel bearings. Unitised bearings, in particular, are preloaded and have zero play, which means there is no wiggle room for runout. Any high and low spots will scrape the brake pads with every revolution of the rotor — braking and non-braking.
    • Calipers. Some have lower running clearance and higher initial mounted lateral runout.
    • Abrasive lining materials.

    The rotor can also show friction variation around its circumference. Any spot that has more slip or stick to it relative to the rest of the rotor will result in different levels of torque. Variations in friction will generally be the result of corrosive or contamination effects. There will most likely also be DTV, but the friction variation is possible without DTV. Friction variations can occur when a vehicle has sat undriven for extended periods of time.

    measuring runout and dtvCold brake roughness

    Cold brake roughness manifests in a similar feel of pedal pulsation or steering wheel vibration, and in severe cases, there will be speed-related surges in deceleration felt during normal driving and light braking. This phenomenon is caused by lateral run-out that exists when the rotors are initially mounted on the car. Over time, this gradually turns into disc thickness variation due to inconsistencies in the lining only touching the higher spots of the rotor during off-brake driving.

    The problem with myths is that are convenient. Assuming you need to wear a hat in winter to avoid catching a cold because your grandmother told you that a thousand times is much easier than actually researching the science behind it. Just put a hat on and hope for the best.

    That mentality is troublesome when it comes to servicing brakes — saying a rotor is warped easily puts the blame on an ineffective part that needs to be replaced when that isn’t the case. Understanding that a warped rotor is a myth is to understand that there are other causes for the braking condition and additional work is needed to do the job right. This may seem like a matter of semantics, but mischaracterising the root problems of pulsation just perpetuates the myth.

  • How to Prevent Brake Rotor Warping

    Brakes are an important part of any vehicle, car or motorcycle, and it is essential to have every component of the brakes in top working order to ensure your safety and that of your passengers. Sometimes, brake rotors can warp, causing a throbbing or pulsing sensation when you apply the car brakes and while coming to a stop.

    Brake rotors warp as a result of the rotor becoming distorted; however, rotor warping can also refer to uneven wear patterns on the rotors that produce the same throb or pulse. To prevent rotors from warping, there are certain things to consider.

    Install a High-Quality Brake Rotor

    If your brake rotors are already warped, you need to replace them with new ones. It is best to use a brake rotor of high-quality metal and weight because these rotors remove heat more effectively than others.

    The heavier metal rotor reduces the distortion from warping by stopping heat damage and allows the rotor to operate using cooler temperatures. This also prolongs the life of your brake rotor and reduces the wear and tear on your brake pads.

    Install Brake Pads

    If your brake rotors have been warped for a long period, you might need to consider installing new brake pads. Over time, the warped rotors cause the brake pads to wear unevenly and quicker. Be sure the new brake pads are appropriate for your vehicle; for example, ceramic pads built for high temperatures are made for racing vehicles that use extreme braking conditions. If you use these on a normal vehicle, you will cause premature wear of the rotor and a poor performance at normal speeds.

    Break in the Pads and Rotors

    Once you have installed new brake rotors and pads, you must break them in properly. Brake pads clean the rotor and apply the right amount of friction to stop the vehicle. Not breaking in the rotors and pads could reduce the ability of the pad to clean the rotor sufficiently. This can cause uneven wear or warping.

    Each vehicle has its own regulations for break-in procedures, although general guidelines are helpful. When you are ready to break in your new rotors and pads, do so in an empty parking lot or vacant street. Always be safe.

    Breaking in Brake Pads

    • Start driving and continue until you reach 40 miles per hour. Engage a hard brake once you reach 40 mph, but do not come to a complete stop. (A hard brake is where you "slam" on the brakes.)
    • Start accelerating again to 50 miles per hour and slam on the brakes again just until the ABS has been engaged (approximately 10 miles per hour). Again, do not come to a complete stop.
    • Repeat the above two steps for a total of four times.
    • So far, you should not have completely stopped yet. Accelerate to 65 miles per hour, and then take your foot off the gas and coast to 15 miles per hour. Once at 15 miles per hour, brake slowly until you come to a complete stop.
    • Park the vehicle and let the car cool off for 20 minutes.

    When applying this procedure, there should not be a lot of gaps between the hard stops, meaning you should accelerate quickly. Do not come to a full stop during a hard stop, as this will imprint the pad on the rotor and cause vibration. It is normal to see smoke, smell odours, and hear squeaking sounds during this process.

    Once the above process is complete, you need to drive at least 400 miles before the pads are fully embedded into the rotors and giving you optimum performance. Remember, it is important to read the manual for the brake pads and rotors, since the specific break-in procedure may be different; however, if no procedure is provided, use the one above.

    Preventing Brake Rotor Warping in the Future

    After the break-in procedure, it is important to prevent warping from happening again, or you might be continuously purchasing new rotors and pads before their time.

    First, try to avoid driving through puddles of water. Generally, puddles are cool water, and if your brakes are heated (and they do heat quickly), the cool water will cool them off too quickly and could distort the metal.

    Anytime the lug nuts on the wheels must be removed, they should be evenly tightened again. Using either the cross pattern or the star pattern, tighten the lugs so there is no uneven clamping between the wheel, rotor, and hub.

    You should also clean the brakes and rotors with brake cleaner at least once a month. This will remove particles that could be embedded into the rotor surface and cause warping.

    Types of Brake Rotors

    There are actually quite a few rotor types, and each of these is meant to do something different. First, you have the normal rotors that came with the vehicle. These are simple rotors cast in iron and come in a variety of diameters and thicknesses.

    Cross-drilled rotors are another type and have holes drilled all around them. These holes are spread out over the surface of the rotor and help the rotor cool down during hard braking situations. They are used for high-performance vehicles (race cars) because of the constant stop-and-go of these cars. These rotors are also being used in everyday vehicles because it makes an improvement on their braking; however, many vehicles cannot handle these cross-drilled rotors, and it can cause the rotor to wear more quickly. Be certain your vehicle can use these rotors before purchasing them.

    Another type includes the vented rotor. These have small "veins" or vents inside the rotor that also help keep the rotor cool during the braking process. These vents are created during the casting process to uphold the integrity of the rotor. Slotted rotors are also used to cool brakes and are generally placed on an angle.

    You may also find rotors that have all three of these types in one: cross drilling, slots, and vents. This allows the maximum cooling ability but is not always meant for use on regular vehicles.

    How to Find Brake Rotors on DBC

    If you have warped rotors, whether on a car or motorcycle, you will need to replace the brake pads and rotors before doing anything else. Utilise the DBC search bar to find brake rotors, or any other part, by typing in specific keywords, such as "brake rotors." You will probably see hundreds of thousands of options available to you, but it is easy to narrow your search. The results will include a grey box for you to select the information for your particular vehicle including year, make, model, trim, and engine. This will allow you to look at only those that will match your specific vehicle, which can be a big time saver.

    You must first select a year before selecting anything else. In some cases, you can find sets, which include the brake pads and rotors for either the front or back (or both). If all the rotors need replaced, DBC is a great option.


    The best scenario is to prevent brake rotor warping, but if you already have this problem, it is important to take care of it as soon as possible by replacing the rotors and brake pads. Consider different types of rotors to give you the best cooling brake system available for your vehicle to ensure that brakes cool properly and to guarantee there is no more warping.

    After replacement, you will need to break in the rotors and pads according to the manual or the guidelines provided. To keep the rotors in the best working order, be sure to lubricate the rotors, pads, and wheel hubs properly as needed, and refrain from driving into puddles when your rotors are overheated due to excessive braking.

  • 5 Car Repairs You Can't Afford to Skip



    No matter what strange noise your car is making, it almost always turns into the ca-ching of your mechanic's cash register gobbling up your cash. Because car repairs are expensive, it's tempting to let them slide. But putting off or skipping certain repairs can be a costly and even dangerous game.

    Here are five car repairs you might be tempted to skip in order to save a few bucks. But we'll show you how making that call could cost you a lot more in the long run. Most figures provided are based on service estimates from RepairPal, an online provider of independent and unbiased repair estimates, and are for the Washington, DC area. Be sure to visit their site to see how much you can expect to pay at your local mechanic shop.

    1. Installing Fresh Brake Pads

    Common sense dictates that you shouldn’t neglect your car's brakes. Still, when it comes time to replace brake pads, it's easy to look the other way. After all, brake pads tend to wear gradually, so it may take some time before you notice changes in braking performance. Delaying the fix, however, can prove costly and dangerous.

    “If you neglect your brake pads and shoes, your brakes will ultimately fail,” write the pros at Car Talk. “Even before that happens, however, you can cause damage to other, more expensive brake parts, such as rotors, drums and calipers. In other words: a stitch in time ... saves you from helping your mechanic with a boat payment later on.”

    Rotors are especially costly to repair or replace. As they rub against worn brake pads, rotors become warped, which makes it tougher to stop the car (if you feel your car shudder as you brake, you probably have warped rotors). Fixing them requires that they be turned or smoothed out by a mechanic -- if, of course, they can be salvaged at all.

    How much can you save by staying on top of your brake pads? Lots. According to RepairPal, replacing the front brake pads on a 2010 Honda Civic can cost anywhere from $144 to $207. If, however, the front rotors need to be resurfaced, the price increases to $208 to $289. Still, that’s cheaper than replacing a pair of front brake pads and rotors – which costs a whopping $372 to $485.

    2. Changing Your Oil

    Not changing your car’s motor oil on a regular schedule can be detrimental to its health.

    According to Midas, “Oil is the lifeblood of your engine. It reduces friction, lessens wear, provides lubrication, forms a seal between the pistons, rings and cylinder walls while helping to cool engine parts. Without the cleaning action of new oil, carbon and varnish buildup would be toxic to the engine.”

    Oil Change
    Karunyapas Krueklad / EyeEm / Getty Images

    Fortunately, an oil change is easy enough to do yourself. It’s also cheap enough to have a pro do it for you. While most service stations recommend that your car has its oil changed every three months or 3,000 miles, many new cars can travel up to twice that distance without needing one. To find out how long your car can go between oil changes, check your owner's manual.

    After you've figured out the recommended oil change interval for your car, stick to it. RepairPalreports that an oil and filter change on a 2010 Ford Fusion costs between $27 and $45. The price of a new engine? That’ll run you four figures.

    3. Replacing Your Air Filter

    Changing an air filter is relatively inexpensive. However, ignoring a clogged one can cost you big bucks at the pump and the mechanic shop.

    “This critical member of the performance system requires careful attention if the engine is to operate at peak performance and deliver maximum fuel efficiency,” writes AOL Autos. “The air filter screens out harmful dirt and grime that would otherwise find its way into the engine. This grit can and does cause internal engine wear. It can score cylinder walls and stick to close-tolerance mating surfaces, and cause bearing and lubricating surface wear.”

    According to a recent study by Oak Ridge National Laboratory, a new air filter can increase the fuel economy of a carbureted engine by two to 14 percent, depending on how clogged the old filter was. While there’s no fuel-economy gain for fuel-injected engines, a new air filter does enhance vehicle performance -- providing six to 11 percent faster acceleration time.

    So what will it cost? RepairPal says that having a pro install a new air filter on a 2010 Chevrolet Cobalt will run $47 to $69. Or you can buy one at your local auto supply store for under $40 and install it yourself -- it’s really easy to do. Either expense is pocket change in comparison to the long-term cost of decreased fuel economy. It’s also a bargain compared to the cost of what may happen if you continue to drive with a dirty air filter. For instance, a dirty air filter can prevent sufficient air from reaching your car’s engine, fouling the spark plugs. RepairPal reports that replacing a set of those on a Cobolt will cost $105 to $138.

    4. Replacing Your Fuel Filter

    To keep your engine running at optimal performance, impurities need to be kept out. While the air filter prevents airborne matter from polluting the engine’s components, the fuel filter does the same for whatever sediment may be in your gasoline. Like the air filter, the fuel filter needs to be replaced from time to time in order to prevent a much costlier fix.

    "The fuel from the fuel tank is typically pumped from a pump inside the fuel tank to the engine,” writes Jiffy Lube. “In the line between the fuel tank and the engine, a fuel filter is typically present to help protect the fuel system. As a fuel filter slowly becomes clogged, the restricted fuel flow could lead to poor acceleration and reduced engine performance as well as other issues.”

    On older cars, a fuel filter is relatively easy to replace because it's easy for mechanics or car owners themselves to get to. On newer cars, it's a more complex job. More complexity means more money, which makes this repair tempting to skip -- despite the fact that it can lead to dirty fuel injectors, which could make your car stall or refuse to start altogether.

    Don't skip it. The difference in price between replacing your fuel filter and fuel injectors is significant. According to RepairPal, replacing a single fuel injector on a 2010 Nissan Altima can run as high as $437. Replacing a fuel filter, on the other hand, starts as low as $88.

    5. Installing New Headlight Bulbs

    Here's one car repair on our list that is really easy to ignore. After all, a burned-out headlight won't eventually lead to engine failure or to your transmission falling out. It could, however, lead to a costly fine or accident.

    Mihajlo Maricic / EyeEm / Getty Images

    “As well as your car or truck may be running, if you can't see where you're going you're not going to enjoy driving it,” explains Popular Mechanics. “Your night visibility is totally dependent on your vehicle's headlights. If one headlight is burned out, your night visibility is cut in half.”

    Indeed, failure to keep your headlights working can be an expensive proposition. First, if a police officer sees you with a burned bulb, you're going to get a ticket. That fine could make paying a few dollars for a new bulb seems like chump change. Second, broken lights increase your risk of being in a crash. Even if you don’t harm yourself or anyone else, you’ll still have to deal with the headache of getting your car fixed.

    Who needs that? Replacing a burned bulb is easy and inexpensive. You can order one online for as low as five dollars or, if you’re not handy, have a pro do it for you. RepairPal estimates that the fix will cost between $56 and $77 on a 2010 Volvo XC70.

  • Is it Safe to Drive With Warped Rotors?

    Warped Rotor

    The rotors are part of the disc brakes that allow your vehicle to stop once the vehicle is in motion. If the rotors are warped, your vehicle may not be able to stop properly in an emergency situation. This can be dangerous if you need to stop to avoid a car accident, pedestrian, or another driving situation. As soon as you start to realise the brakes are not working like they should, you should contact a mechanic and have them check for warped rotors.

    There are many steps you can take if you discover that you have warped rotors. If you are driving with warped rotors, here are some things to consider:

    • Rotors wear down over time, which can decrease their reliability. The brake system, such as rotors, calipers, and pads, should be inspected on a regular basis because they do wear down.
    • One danger of warped rotors is the increased stopping time. Even if the surface is smooth, the vehicle will still take longer to stop. If the warped rotor is on the drive axle of the car, the stopping time of your vehicle will be more noticeable.
    • A warped rotor can cause the brakes to temporarily fail. The warped rotor causes the brake pads to wiggle back and forth, which causes the brake fluid to foam up so the braking system does not get the proper amount of hydraulic pressure. If you temporarily lose control of your brakes, this can cause you to hit vehicles around you.
    • While driving, if you feel vibrations in your brake pedals, this may be a sign that you have a warped rotor. Sometimes the vibration can be felt with only a small amount of brake pressure, where other times it will take more pressure to feel the vibrations. Either way, once you start feeling this, contact a mechanic so they can fix the problem.
    • Brake noise is another sign your rotors may be warped. This is because the rotors will be contacting your brake pads unevenly. The noise can sound like a thumping or a pitched hum.

    If you suspect you have warped rotors or your brakes are failing, it is important that you avoid driving your vehicle and contact a mechanic right away. Driving with warped rotors potentially will result in a brake system failure, which can cause injury to yourself and those around you. To keep yourself and others around you safe, have your warped rotor problem repaired before you get back on the road.

  • Part One: Rotors Don't Warp

    Brake rotors do not warp from heat, even when driven by the most aggressive traf­fic officer. Instead, they wear unevenly. This uneven wear is caused by the brake pads themselves as they intermittently touch an out-of-true rotor. The root cause of the uneven wear is one of two things: either the rotor was installed out-of-true with the hub, or the tire was improperly torqued to the hub during the last tire change.

    All of this is important for fleet managers because their vehicles have the tires removed frequently and the pads and rotors replaced frequently. You won’t solve a problem caused by wear if you treat it as a problem caused by heat. Instead, fix the rotor installation or wheel lug nut torquing.

    The problem of pedal vibration, incorrectly called rotor warp, occurs 3,000 to 5,000 miles after the brake or tire change. Because it is caused by uneven rotor wear, not the rotor warping like a potato chip from heat, you can’t solve this wear problem by better control of the heat, i.e., by the use of specially processed rotors or drilled and slotted rotors. Instead, you solve the wear problem by fixing the shortcuts in rotor installation or the improper lug nut tightening.

    By taking a few steps, the fleet manager can easily, quickly and permanently fix the pedal pulsation problem. First, for each rotor change, verify the runout of the rotor, and then do one or two quick things to have it less than 0.002 inch, which is the OE spec for most vehicles. Two, for each tire and wheel change or rotation, torque the lugs in a star pattern using either a torque wrench or torque stick. Those two steps will virtually eliminate premature rotor wear, period.

    Think about it this way: What are your conservative officers doing to their cars to “warp” the brake rotors in less than 5,000 miles? They don’t get the brakes warm (350 F), let alone patrol-hot (600 F), and never pursuit-hot (850 F). Yet their rotors are warping? No. They are not warping. They are unevenly wearing during the times of zero brake pedal pressure, and your officers are not doing anything to either prevent it or cause it.

    Foundation Brakes

    While a lot more was covered, that is the essence of the four-day Affinia-Raybestos Brake System Diagnosis & Repair Course, i.e., Foundation Brakes. This course is half classroom-based and half hands-on. It is held at Affinia-Raybestos headquarters in McHenry, IL and is also conducted at locations across the nation. Class sizes run a maximum of 12 because of all the hands-on work.

    The Foundation Brake class covers hydraulic braking theory, brake system dynamics, diagnostics, troubleshooting, repair techniques, preventative maintenance practices, rotor resurfacing techniques, bench and on-car lathe operation, brake (friction) pad materials and noise and dust solutions.

    The Foundation Brake class is not one bit product-oriented. It is not a veiled sales job. It is tech training, and you will get your hands dirty. You will install Raybestos pads, rotors and calipers in this class and Raybestos master cylinders, hoses, lines and valves in other classes. However, brand to brand comparisons are never made, and brand names are seldom mentioned.

    Instead, the brake tech school is all about brake jobs, accurate diagnosis, fixing it right the first time and preventing comebacks—not about what brand of pad or rotor is better than another. Police Fleet Managerattended the course and recommends it, without reservation, to all new police fleet managers, new maintenance techs, and as a refresher for veteran maintenance techs and new shop superintendents or maintenance supervisors.

    Just as important as the Foundation Brakes class is for many maintenance techs, so is the three-day Affinia-Raybestos ASE Brake Test Preparation Course. This course provides information, training and sample testing to help techs prepare for ASE Brake Test A5. Affinia-Raybestos also has shorter, stand-alone, hands-on brake lathe (both bench type and on-car), brake system diagnostics and installation, ABS advanced diagnosis and service, and a variety of chassis-suspension and steering courses.

    The brake foundations course started the way that all “real” training classes start: with a pre-test. What is the most effective way to pinpoint a spongy brake pedal? Perform an isolation test by clamping all of the brake line hoses. What type of seal is used around the piston in the caliper? A Square Cut Seal.

    A metering valve restricts initial pressure to where? The front brakes. A proportioning valve limits pressure under hard braking to where? The rear brakes. What is the probable cause for a car with a spongy pedal? Air in the system. Improper lug nut torque or tightening sequence causes rotors to “warp.” True.

    Tightening Sequence

    That last question is where the class instruction started. In the old days, star-pattern tightening using torque wrenches was the only way lug nuts were tightened. Not any more. Today, it is throw the tire and wheel over the lugs, hand start the five lug nuts, then use an air wrench in a once-around circle pattern, and you are done.

    Doing this, the first few wheel lugs lock the rotor into location while the last few wheel lugs pre-load the rotor, which is like slightly bending a spring. Even worse, even if perfectly tightened to 100 ft-lbs, the last few lugs are false readings. Some of the torque is absorbed in flexing the rotor, not tightening the lug. This is almost guaranteed to cause uneven rotor wear (incorrectly called warped rotors), which results in the tell-tale pedal pulsations after just a few thousand miles.

    The unevenly torqued rotor, even with the correct amount of torque, will not be bent when the rotor is cold. However, as the rotor heats up in normal use, it will expand unevenly. The most uneven area will, of course, be near the first tightened and last tightened lugs. As the rotor heats up and expands, a runout will be caused, i.e., a high spot on one side and a high spot on the other side. These high spots will come into intermittent contact with the retracted pads during normal driving, i.e., without brake pedal pressure.

    As this happens, the semi-metallic pad used with police cars will grind away the high spots on either side. On the other hand, the ceramic pad used with retail cars will transfer material to the high spots. In just a few thousand miles, the rotor will have a significant thickness variation, either from worn away rotor or material transfer from the pad. Rotor thickness variation causes brake pedal pulsation and steering wheel vibration!

    Air Wrench Blues

    The wrong tightening sequence, even with the right amount of torque, can cause a rotor problem. So can the right tightening sequence with the wrong amount of torque. (No, your air impact wrenches are not calibrated!) Here is what happens.

    The air wrench increases or decreases in torque as it is being used. The line pressure falls, the air compressor kicks in, the line pressure increases. The result is that an air wrench nominally set at 100 ft-lbs may actually torque the lug nuts to 85, 110, 100, 90, 110, 90. Any variation above 10 percent is bad. The result is exactly the same in the situation where warming causes uneven expansion, as in the situation with the incorrect circular tightening sequence situation.

    These two causes of premature rotor wear can be easily fixed. First, use a star pattern instead of a circle pattern to tighten the lugs. Second, for those using a torque wrench, first pre-tighten the lugs with the socket wrench, then tighten them afterwards with the torque wrench. Don’t overdo it with the socket wrench. The torque wrench must be allowed to tighten the lug at least a little. If it clicks-out without tightening the nut at all, the nut could be way over-torqued. That is what happens if you use a breaker bar for the initial tightening.

    Third, for those using an air wrench, use torque sticks. Or set the air wrenches under the necessary torque and finish them off with a torque wrench. Rule one: star pattern. Rule two: torque sticks or torque wrench. Follow these rules every time you replace a tire.

    The “Proper” Brake Job

    Properly tightening the lug nuts prevents one major cause of premature rotor wear. The other major cause is “improper” installation of the rotor. And here is where you may get some resistance from your veteran techs who have been doing brake jobs for 10 years. You cannot do a proper brake job without a dial indicator to measure rotor runout.

    Those who have turned a wrench before may think they already know how to properly change brake pads and rotors. This may be. However, if the brake job is performed on a modern two-piece hub and rotor the same way it was on the old one-piece hub and rotor, the job is probably not being done properly. That means the brake job is not being done per OE factory spec and how the OE dealers do it.

    This habit of “continuing to do it the old way” may explain why rotors produce a pedal pulsation, i.e., “warped” rotors in just a few thousand miles. That alone may explain premature pad wear and premature rotor wear, even in premature for police operations.

    “A brake repair shop without a dial indicator is like an engine rebuild shop without a torque wrench,” said Dann Ingebritson, technical instructor, Affinia Under Vehicle Group.

    The rotor lateral runout is a slight wobble or slight wave in the surface of the rotor as it is being rotated. This out-of-true condition can be caused by an out-of-parallel condition of the rotor—even a brand new one or one that just came off the bench lathe. This can also be caused by an out-of-parallel hub mounting surface or by a stack up of out-of-true conditions on both the rotor and hub.

    This runout or wobble will cause exactly the same intermittent contact between the rotor and the pad as the improperly torqued lug nuts. Again, material will be removed from the rotor by semi-met pads, or added to the rotor by ceramic pads in just the high spots. Again, the result is rotor thickness variation which causes brake pedal pulsation and steering wheel vibration. Again, the rotors need replacement in less than 5,000 miles. Again, the officer driving the car does nothing to cause the problem.

    This was not a problem 10 years ago when the runout spec was 0.010 inch or so and the brake pads used softer friction materials. Today, this is a major problem, when the runout is 0.002 inch max and the pads are rock hard.

    Dial Indicator

    When the new or cut rotor is put back on, torque it in place. Clamp a flex-arm dial indicator on a solid part of the suspension, place the indicator tip on the rotor, zero the dial and slowly rotate the rotor. A rotor runout gauge set costs about $50 and is available at any auto parts store or online. Google the term “rotor runout dial indicator” and you will find many. Check the OE spec, but most police sedans call for a maximum runout of 0.002 inch. If the runout is less than that, put the caliper and tire on!

    If you have cleaned the hub with a wire brush or roto-brush, including the surface very close to the lugs, and you are using a new high quality rotor, the majority of the time the runout will be in-spec. If the hub surface is not perfectly clean, if you bought a cheap rotor or if the rotor has been cut on a lathe with an excessive runout, the rotor runout will be out-of-spec. Mark the high spot. Something must be done or this rotor will cause pedal pulsation in just a few thousand miles.

    If the rotor is indicating an excessive amount of lateral runout, the tech has three options. One is a quick and easy option which works about 80 percent of the time, one is a fairly easy but more expensive option that works 95 percent of the time, and one is a slower and harder option that absolutely works every time.

    Rotor Indexing

    The easy solution is to take the rotor off the hub, rotate it about half way around and bolt it back in place. (On the 5-lug police cars, rotate it not quite 180 degrees, one way or the other.) Now indicate the rotor. Most of the time it will now be in-spec.

    Why? The rotor surface has a slight runout and, separately, the hub surface has a slight runout. When you bolt the rotor to the hub, you stack these tolerances. Let’s assume the rotor is out by 0.003 inch and the hub is out by 0.002 inch. Mounted with the high spot of the rotor on top of the higher spot on the hub, the assembly will have a runout of 0.005 inch, which is terrible. Now rotate the rotor on the lug pattern, i.e., “index” the high spot of the rotor over a low spot on the hub, and the runout is just 0.001 inch, which is excellent.

    Indexing the rotor works most of the time. It only takes a few minutes to remove the rotor, rotate it, replace it and indicate it. You may think, “Hey, that’s not in my flat rate.” Actually, it probably is.

    Brake Align Shims

    The fairly easy option that works almost all the time involves the use of Brake Align™correction plates, AKA shims or spacers.

    Again, indicate the mounted rotor and mark the high spot on the rotor. Also, mark the lug, or the two closest lugs, nearest the high spot. Remove the rotor and put the correct shim over the wheel lugs. Put the notch in the correction plate closest to the marked lugs. The notch marks the thinnest part of the shim. Put the rotor back on, just how it came off, and indicate it. It will be in-spec.

    The Brake Align shims come in a wide assortment of thicknesses, in 0.001-inch increments or so to make correction for a variety of runout conditions. If you need a 0.009-inch shim, start replacing parts rather than shimming them.

    The Brake Align shims are a bit expensive at about $20 each. That is a pretty costly solution to an out-of-spec rotor. Cut the rotor on a lathe or send it back to Cheap ‘R’ Us auto parts store where it came from. However, what if the high quality rotor is perfect? What if the excessive runout is in the hub? The Brake Align shim is certainly less expensive than a new hub.

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Cross Drilled Rotors