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Frequently Asked Questions


Brake Kits:
  • Do you make a BIG BRAKE package and how much?
  • Are there any options for this kit?
  • What would the recommended Wheel Size be for this Big Brake system?
  • Iím interested in one of your Wilwood Brake Kits. However I saw it noted that this was for Race Use Only.

  • Rotors:
  • What about Rotors (Discs)
  • What's so great about disc brakes versus drums?
  • Are there any benefits to choosing a two piece rotor over a one piece rotor?
  • How can I decide if cross-drilling or slotting is right for me?
  • Are these rotors cadmium plated?

  • Calipers:
  • How do Brake Calipers work?
  • What are the benefits of opposed-piston fixed calipers?
  • Are the calipers available in colors?
  • How do I tell when it's time to replace my brake calipers?
  • What are Caliper Piston Seals?
  • How does the mechanical spot caliper mount?
  • What is the difference between the Wilwood Billet Dynalite Calipers and the new Forged Dynalites?

  • Brakes Basics:
  • What is Brake Fade?
  • What is a Disc Brake?
  • What comprises the "Brake System"?
  • What is ABS?
  • What about the brake pedal?
  • What's a Wheel (Slave) Cylinder?
  • What's a Master Cylinder?
  • What about Brake Fluid?
  • What about Bleeder Valves?
  • What parts are generally replaced during a brake job, and why?
  • What is "bleeding the brakes" and why is that sometimes necessary?
  • How do I know when my car really needs a brake job?
  • Is it always necessary to resurface the rotors and drums when the brakes are relined?

  • Brake Pads:
  • What about Brake Pads and Brake Shoes?
  • What is the difference between Hawk HPS (High Performance Street) pads and the HP Plus?

  • Brake Hoses and Brake Lines:
  • What about Brake Hoses and Brake Lines?

  • General Troubleshooting:
  • My brakes are squealing. Does that mean I need a brake job?
  • I feel a pulsation or vibration in my brake pedal every time I stop. But the brakes seem to work fine. Is anything wrong?
  • I've heard that using a temporary spare will disable my ABS system. Is that true?
  • My brake pedal slowly sinks to the floor when I hold my foot on it. What's wrong?
  • My brake pedal is low when I step on it, but it comes up when I pump the brakes. Do I need new brakes?
  • Do you have a recommendation for my SUV? The "brakes" are one of my few complaints.

  • Do you make a BIG BRAKE package and how much?
    We don't have a kit for every car sitting on the shelf. If we don't have a kit for YOUR car then we will be happy to put one together for you. We provide custom kits all the time! Prices vary according to the particular specifications.
    We can do anything from 11" to 16", two piece or one piece rotors with 4 or 6 piston calipers.




    Are there any options for this kit?
    Typical options for many front kits include bigger caliper pistons and an upgraded master cylinder to match. We also offer a variety of rotors and an extensive selection of brake pad choices.If front and rear kits are available, you usually get the big calipers for the front and the smaller ones in the rear. The rear kits often include the master cylinder, proportioning valve and steel lines to hook it into the system.



    What would the recommended Wheel Size be for this Big Brake system?
    We have not seen any problems with 17" rims (or larger) clearing many of our brake kits. However, we do make kits for smaller wheels also. If you would like a cross sectional template to test your wheels, we can supply it.



    Iím interested in one of your Wilwood Brake Kits. However I saw it noted that this was for Race Use Only. This is a street application. I just want to improve the stopping power of my car.
    Wilwood puts the "for race use only" warning on all of their products. We have been using their products for street applications for over 15 years without any problems and only a handful of rebuild kits have been sold in that time.



    What about Rotors (Discs)
    The rotor (also called the disc) is clamped by the brake pads in order to slow the vehicle. The rotor is a heavy circular steel plate attached to the wheel providing a two-sided braking surface. Pressurized fluid in the brake lines flows into one or more "slave" cylinders in each caliper. The fluid pressure is exerted against the slave pistons, which force the brake pads against the surface of the disc. As the pads clamp onto the rotor, intense heat is generated, which can in extreme conditions actually cause the rotor to glow red hot!

    The rotor often has a series of radial vents built into it which allow it to be cooled by ambient air. Ventilation ducts directed to the disc allow the intense heat that is generated by the brake to be transferred to the air quickly.

    The surfaces of the rotor are "turned" (re-machined) whenever the brake pads are replaced in order to remove the "glazed" surface which forms on the rotors. The turning process also "trues" the disc (makes it perfectly flat) which eliminates the pulsations which are experienced when the rotor is warped. Warped rotors give a slight tugging when the brakes are applied, and send a pulsing sensation back through the brake pedal.

    Rotors have "minimum thickness" which means if the rotor has been turned several times, it may become too thin to resurface, and therefore require replacement.




    What's so great about disc brakes versus drums?
    Disc brakes are an enormous improvement over drums. They dissipate heat much better, they don't lose their stopping power when wet, their linings last a very long time, they stay in adjustment automatically, and replacing pads is normally a simple job with no return or hold-down springs or self-adjuster mechanisms to mess around with.













    Are these rotors cadmium plated?
    These rotors are actually zinc electroplated, which is durable, and just as effective as cadmium.



    How do Brake Calipers work?
    The caliper works like a C-clamp to pinch the pads onto the rotor. It straddles the rotor and contains the hydraulic "slave cylinder" or "wheel cylinder" piston(s). One caliper is mounted to the suspension members on each wheel. The caliper is usually mounted onto the spindle, allowing it to deliver the torsional force of the wheel to the chassis via the control arms. Brake hoses connect the caliper to the brake lines leading to the master cylinder. A "bleeder valve" is located on each caliper to allow air bubbles to be purged from the system.

    "Floating caliper" disc brakes, the most common variety, allow the caliper to move from side to side slightly when the brakes are applied. This is because only one pad moves (in relation to the caliper). Some calipers contain two or four separate pistons. These calipers are fixed in place; i.e., there is no lateral movement like the floating caliper, the pistons take up the slack on each side of the rotor. These are called "multi-piston" or "opposed piston" fixed calipers, and are standard equipment on many performance cars.




    What are the benefits of opposed-piston fixed calipers?
    A fixed caliper is secured rigidly to the axle assembly and has at least two opposing pistons that force the pads against the disc. A sliding or floating caliper has pistons on only one side of the disc. Therefore, when the caliper acts, it must slide or float in order to bring the pad on the opposite side in contact with the disc. Nearly all original equipment calipers are of the floating type. In a system with fixed calipers, not only is the mounting much more rigid, but the stiffness of the caliper itself is greatly increased. This manifests itself in enhanced braking performance, pedal feel, and pad wear.

    Also, fixed calipers do not suffer the drag (friction) from moving parts common in sliding calipers and are therefore more efficient. These calipers have a much quicker reaction time which translates to shorter stopping distances as measured from the driver's reaction point.




    Are the calipers available in colors?
    Not at this time, just your Basic Black; Goes with Everything!



    How do I tell when it's time to replace my brake calipers?
    Replacing or rebuilding the disc brake calipers is often done when the brakes are relined, but this isn't always absolutely necessary -- but not doing so may be asking for trouble later. A caliper that's leaking brake fluid, is damaged, has a frozen piston, or is causing uneven pad wear obviously needs to be rebuilt or replaced.

    But what about a caliper that isn't leaking and seems to be working fine? Those who subscribe to the "don't fix it unless it's broken" philosophy of brake repair think they're saving time and money by leaving the calipers alone. Maybe so. But most brake experts say it makes sense to go ahead and do the calipers when the brakes are relined. Here's why:

    Brake calipers, like any other mechanical component, wear and corrode with age. Every time the brakes are applied, the back-and-forth motion of the caliper pistons produces a slight amount of wear. At the same time, moisture is building up in the fluid. After several years of service, the fluid may contain as much as 3% water -- which is enough to produce visible corrosion in the caliper bores and on steel pistons. As the surface of the pistons become rough, they scour the seals with every application of the brakes. Eventually this will lead to fluid leaks and pad contamination.

    So even if a caliper isn't leaking, it's still aging inside. Rubber piston seals and dust boots harden and become brittle over time. One of the jobs the piston seals do besides keep the fluid where it belongs is to help retract the pistons when the brakes are released. When a piston moves out, it twists the square cut seal slightly. This helps pull the piston back when the brakes are released to keep the pads from dragging against the rotors. But as a seal ages and loses elasticity, it doesn't do as good a job of pulling back the piston. Consequently, the pads start to drag resulting in reduced fuel economy, a possible brake pull and/or accelerated or uneven pad wear.

    When boots get old, they often crack or split, allowing dirt and water to enter the piston bore area. The result can be accelerated seal wear, piston corrosion and sticking. What's more, if the pistons are pushed back in to accept new pads any dirt that's found its way behind the boots may be shoved back into the caliper bores. This too, can contribute to sticking, binding and wear.




    What are Caliper Piston Seals?
    The caliper piston seals are designed to keep the fluid pressure behind the pistons, and to retract the pistons enough to allow the brake pads to just barely clear the rotor, thus reducing rolling resistance. The seals should NEVER leak. If a leak is detected, it must be repaired immediately, because the fluid which escapes can defeat braking power by getting on the disc, and the pressure loss can affect brake safety.



    How does the mechanical spot caliper mount? Is it with the two bolts that hold the two halves of the caliper together?
    It mounts on two opposed slide rails which engage the grooves / slots on either end of the caliper. The caliper floats in the bracket.



    What is the difference between the Wilwood Billet Dynalite Calipers and the new Forged Dynalites?
    Many of the calipers on the site shown are the Billet Dynalite Calipers. The calipers that we are now providing in many of our kits are the upgraded Forged Dynalite Calipers. These calipers are relatively new from Wilwood, and since their release, we have been using them in place of the Billet Dynalites in our kits, and when sold separately. The great thing about these calipers is that they are the exact same in dimensions (piston sizes and outer dimensions), but they are much stronger. The forging process makes them a lot more rigid.



    What is Brake Fade?




    What is a Disc Brake?
    A type of brake consisting of a flat rotor (disc) that turns with the wheel, and a stationary component called the caliper. Braking is accomplished when the caliper forces pads made of friction material against both sides of the rotating disc. Disc brakes typically provide more linear response and operate more efficiently at high temperatures than drum brakes.

    Disc brakes use a clamping action to produce friction between the "rotor" and the "pads" mounted in the "caliper" attached to the suspension members. Inside the calipers, pistons press against the pads due to pressure generated in the master cylinder. The pads then rub against the rotor, slowing the vehicle. Disc brakes work using much the same basic principle as the brakes on a bicycle; as the caliper pinches the wheel with pads on both sides, it slows the bicycle. Disc brakes offer higher performance braking, simpler design, lighter weight, and better resistance to water interference than drum brakes.

    The greatest advantage of disc brakes is that they provide significantly better resistance to "brake fade" compared to drum type braking systems.

    Disc brakes, like many automotive innovations, were originally developed for auto racing, but are now standard equipment on virtually every car made. On most cars, the front brakes are of the disc type, and the rear brakes are of the "drum" type. Drum brakes use two semi-circular shoes to press outward against the inner surfaces of a steel drum. Older cars often had drum brakes on all four wheels, and many new cars now have 4-wheel disc brakes.

    Because disc brakes can fling off water more easily than drum brakes, they work much better in wet conditions. This is not to say that water does not affect them, it definitely does. If you splash through a puddle and then try to apply the brakes, your brakes may not work at all for a few seconds! Disc brakes also allow better airflow cooling, which also increases their effectiveness. Some high performance disc brakes have drilled or slotted holes through the face of the rotor, which helps to prevent the pads from "glazing" (becoming hardened due to heat). Disc brakes were introduced as standard equipment on most cars in the early seventies




    What comprises the "Brake System"?
    The brake system is composed of the following basic components: The master cylinder which is located under the hood, and is directly connected to the brake pedal, converts your foot's mechanical pressure into hydraulic pressure. Steel brake lines and flexible brake hoses connect the master cylinder to the slave cylinders located at each wheel. Brake fluid, specially designed to work in extreme conditions, fills the system. Shoes and brake pads are pushed by the slave cylinders to contact the drums and rotors thus causing drag, which (hopefully) slows the car.



    What is ABS?
    "Anti-lock" (ABS) systems were originally developed for aircraft braking systems. They use computer controlled valves to limit the pressure delivered to each slave cylinder. It basically works by limiting the pressure to any wheel which decelerates too rapidly. If a wheel locks up, steering input cannot affect the car's direction. With ABS, no matter how hard the pedal is pressed, each wheel is prevented from locking up. This prevents skidding (and allows the driver to steer while panic-braking).

    If standard brakes are applied too hard, the wheels "lock" or skid, which prevents them from giving directional control. If directional control (steering) is lost, the vehicle skids in a straight line wherever it is going. ABS allows the driver to steer during hard braking, which allows you to control the car much better. In the old days, drivers had to know how to "pump" the brakes or sense the lockup and release foot pressure in order to prevent skidding. This meant that if only one wheel lost traction and started to skid, the driver would have to reduce braking force to prevent a skid. The advantage of ABS is that the brakes on the wheels with good traction can be used to the fullest possible amount, even if other wheels lose traction.

    In operation, the wheel speed sensors at each wheel send electronic pulse signals to the control unit. If wheel lockup (rapid deceleration) is detected during brake application, the computer signals the valve unit to limit the hydraulic pressure to the wheel cylinder. This is usually accomplished by diverting the fluid into a small reservoir. The fluid is later pumped out of the reservoir and returned to the main fluid reservoir when the brakes are not being applied.

    The anti-lock brake system tests itself every time the vehicle is started and every time the brakes are applied. The system evaluates its own signals. If a defect is detected, the system then turns off, leaving normal braking unaffected.




    What about the brake pedal?
    The brake pedal gives feedback to the driver which can be beneficial to good maintenance, and therefore potentially save your life. If the pedal pulses when pressed, the usual culprit is a warped rotor, which is potentially destructive to the caliper. If the pedal squishes down when pressure is applied, a dangerous leak is likely present (even if fluid does not drip out anywhere). Your brake pedal should not move more than a small amount when you press it, no matter how hard it is pressed. It should not feel sponge-like: a spongy pedal spells trouble in the braking system. With the car parked and the engine running, press the brake pedal firmly and hold the pressure. If the pedal sinks slowly, a leak is present.



    What's a Wheel (Slave) Cylinder?
    Wheel cylinders, also called the "slave" cylinders, are cylinders in which movable piston(s) convert hydraulic brake fluid pressure into mechanical force. Hydraulic pressure against the piston(s) within the wheel cylinder forces the brake shoes or pads against the machined surfaces of the drum or rotor. There is one cylinder (or more in some systems) for each wheel.
    In disc brakes, the wheel cylinder is built into the caliper. All wheel cylinders have bleeder screws (or bleeder valves) to allow the system to be purged of air bubbles.

    As the brake pedal is depressed, it moves pistons within the master cylinder, pressurizing the brake fluid in the brake lines and slave cylinders at each wheel. The fluid pressure causes the wheel cylinders' pistons to move, which forces the shoes or pads against the brake drums or rotors. On disc brakes, the calipers' piston seals are designed to retract the piston slightly, thus allowing the pads to clear the rotor and thereby reduce rolling friction.




    What's a Master Cylinder?
    The master cylinder displaces hydraulic pressure to the rest of the brake system. It holds THE most important fluid in your car, the brake fluid.

    It actually controls two separate subsystems which are jointly activated by the brake pedal. This is done so that in case a major leak occurs in one system, the other will still function.

    The two systems may be supplied by separate fluid reservoirs, or they may be supplied by a common reservoir. Some brake subsystems are divided front/rear and some are diagonally separated. When you press the brake pedal, a push rod connected to the pedal moves the "primary piston" forward inside the master cylinder. The primary piston activates one of the two subsystems. The hydraulic pressure created, and the force of the primary piston spring, moves the secondary piston forward. When the forward movement of the pistons causes their primary cups to cover the bypass holes, hydraulic pressure builds up and is transmitted to the wheel cylinders. When the brake pedal retracts, the pistons allow fluid from the reservoir(s) to refill the chamber if needed.

    Electronic sensors within the master cylinder are used to monitor the level of the fluid in the reservoirs, and to alert the driver if a pressure imbalance develops between the two systems. If the brake light comes on, the fluid level in the reservoir(s) should be checked. If the level is low, more fluid should be added, and the leak should be found and repaired as soon as possible. BE SURE TO USE THE RIGHT BRAKE FLUID FOR YOUR VEHICLE. Use of improper brake fluid can "contaminate the system". If this occurs, ALL of the seals in the brake system must be replaced.




    What about Brake Fluid?
    Brake fluid is a special liquid for use in hydraulic brake systems, which must meet highly exact performance specifications. It is designed to be impervious to wide temperature changes and to not suffer any significant changes in important physical characteristics such as compressibility over the operating temperature range. The fluid is designed to not boil, even when exposed to the extreme temperatures of the brakes.

    Different types of brake fluid are used in different systems, and should NEVER be mixed. Most cars use "DOT 3" or "DOT 4" brake fluid. Some newer cars use silicone brake fluids. These should NEVER be mixed together, because the seals in each car are designed to work with only their specific fluid types. For example, the mixing of "Silicone" brake fluid and conventional glycol based DOT 3 or DOT 4 fluids should be avoided, as the two fluid types are not miscible (they will not mix together). DOT 3 brake fluids and DOT 4 brake fluids can be mixed.

    One of the WORST things that can happen to your car is if the brake fluid becomes contaminated, because the seals are designed to work with only pure brake fluid. "System contamination" means that all of the piston seals and hoses are deteriorating, and therefore must be replaced, a MAJOR expense. So, be VERY careful what you put in the master cylinder reservoir!

    It should be noted that brake fluid is highly corrosive to paint, and care should be used not to get it on your car's finish.




    What about Bleeder Valves?
    Since the brake system is filled with fluid, it must be occasionally "bled". (the old fluid is released in order to install new fluid). This is also done to remove any air bubbles that have gotten into the system (usually when any of the brake parts are changed). All hydraulic brakes have bleeder valves on or near the slave cylinders. These valves are opened while the brake pedal is pressed, causing the brake fluid to flow out as well as any air bubbles present.

    When the brake fluid comes out without any air bubbles, the mechanic seals the bleeder valve and tops off the brake fluid reservoir. Bleeder valves can also be found on the side of some master cylinders. These are used for the same purpose; getting air bubbles out of the master cylinder assembly. If you have air bubbles in your fluid, your pedal will feel softer than normal, and braking power will be reduced, so it is a good idea to have your brakes bled and the fluid changed according to your owner's manual.




    What parts are generally replaced during a brake job, and why?
    Answer: A traditional brake job (if there is such a thing) usually means replacing the front disc brake pads, resurfacing the rotors, replacing the rear drum brake shoes, resurfacing the drums, bleeding the brake lines (replacing the old brake fluid with new and getting all the air out of the lines), inspecting the system for leaks or other problems that might require additional repairs, and checking and adjusting the parking brake.
    Some brake jobs may also include new hardware for the drums (recommended), and rebuilding or replacing the wheel cylinders and calipers (also recommended). But because of the added expense, these items may not be included in the package price or may only be done if the brake system really needs them (as opposed to doing them for preventative maintenance).

    Hardware includes things like return springs, holddown springs and other clips and retainers found in drum brakes. It may also include bushings, pins and clips on disc brake calipers. Springs lose tension with age and exposure to heat. Most experts recommend replacing the hardware when relining drum brakes to restore proper brake action. If weak springs are reused, the shoes may drag against the drums causing accelerated shoe wear, a pull to one side, brake overheating and possible drum warpage. Other hardware that is badly corroded or faulty (such as the self-adjusters) may prevent the shoes from maintaining the correct drum clearance (which increases the distance the brake pedal must travel as the shoes wear), or the parking brake from functioning properly.

    It's important to note that not all replacement linings are the same. There are usually several grades of quality in pads and shoes (good, better and best). The difference is in the ingredients that are used to manufacture the pads and shoes. The less expensive ones may cost less initially and save you a few dollars on your total bill, but you may not be happy with the way they wear and perform. All brake linings must meet minimum government safety standards. Even so, the cheaper grade of pads and shoes do not last as many miles as the premium grade of replacement linings, nor do they brake as effectively. They usually have a greater tendency to fade at high temperature and may increase the vehicle's stopping distance somewhat. The best performance and value for your money, therefore, is with the best or premium grade. Choose these when the brakes are relined.




    What is "bleeding the brakes" and why is that sometimes necessary?
    Bleeding the brakes is flushing the old brake fluid out of the master cylinder, brake lines, calipers and wheel cylinders and replacing it with fresh fluid.
    Bleeding is necessary for two reasons:

    1. To remove air bubbles that may have entered the system while repairs were being made, because of a leak or because the fluid level got too low. The air must be removed because it is compressible and can prevent a full, firm pedal.

      The individual brake lines must be bled in a specified sequence (which varies from vehicle to vehicle depending on the design of the brake system) to remove all the air from the lines. On some ABS-equipped vehicles, special bleeding procedures may be required (which also requires special equipment in some cases such as a scan tool to cycle the ABS solenoids).

      The brakes can be bled manually by attaching a piece of clear tubing to the bleeder screw on each caliper and wheel cylinder, opening the screw and manually stroking the brake pedal to force fluid through the lines, or with power bleeding equipment. Most professionals use power bleeding equipment because it's faster and easier.

    2. To remove moisture contamination. Brake fluid needs to be replaced periodically because DOT 3 and 4 brake fluids are glycol-based and absorb moisture over time. This occurs whether a vehicle is driven 30,000 miles a year or just sits in a garage because fluid contamination is a function of time and humidity rather than mileage. Moisture enters the system past seals and through microscopic pores in hoses. It also enters every time the fluid reservoir is opened (a good reason not to do so unnecessarily).

      After only a year of service, DOT 3 fluid may contain as much as 2% water. After 18 months, the level of contamination can be as high as 3%. And after several years of service, it's not unusual to find brake fluid that has soaked up as much as 7 to 8% water. Many vehicles that are six, seven or eight years old have never had the brake fluid changed!

      As the fluid soaks up moisture, it thickens and becomes less able to withstand heat and corrosion. The result is a significant drop in the fluid's boiling temperature, which may under the right conditions allow the fluid to boil in the calipers. Once brake fluid turns to vapor, the bubbles cause an increase in the distance the pedal must travel to apply the brakes. This condition should not be confused with "brake fade" that occurs when the brake linings get too hot as a result of prolonged braking. Brake fade requires greater and greater pedal effort to stop the vehicle while fluid boil increases pedal travel and makes the pedal feel soft or mushy. The danger of fluid boil is greatest in more modern cars, SUV's and trucks because of the higher operating temperatures that are generated in today's downsized front brakes, resulting from the increased weight of the vehicle. Semi-metallic linings, while typically more aggressive and able to operate at higher temperatures, tend to compound the heat problem by conducting heat from the rotors to the calipers. If the fluid contains a lot of moisture and can't take the heat, it'll probably boil.

      DOT 3 brake fluid, which has long been used in most domestic cars and light trucks, has a minimum dry boiling point of 401 degrees F. A 3% level of water contamination will lower this by 25% or 100 degrees! DOT 4 "extra heavy-duty" brake fluid, which is used in many European cars, has a higher dry boiling point of 446 degrees F. DOT 4 soaks up moisture at a slower rate than DOT 3 but suffers a greater drop in heat resistance as moisture builds up. Only 2% moisture in DOT 4 fluid will lower its boiling point by almost 50% or 200 degrees!

      CAUTION: Use the type of brake fluid specified by the vehicle manufacturer. Never substitute DOT 3 for DOT 4. But you can safely substitute DOT 4 for DOT 3. Though the owner's manuals for most domestic vehicles have no specific time or mileage recommendations for replacing brake fluid, a change every year for preventative maintenance is a good way to minimize the danger of fluid boil and internal corrosion in the brake system. At the very least, the fluid should always be replaced when the brakes are relined.

      Some people say using DOT 5 silicone fluid eliminates moisture contamination problems. The premium-priced fluid, which is silicone based, does not absorb moisture and is theoretically a"lifetime" brake fluid. What's more, DOT 5 fluid has a higher dry boiling point of at least 500 degrees F. and a wet boiling point of 356 degrees F. But DOT 5 silicone brake fluid is very expensive (up to ten times as much as regular brake fluid!). It does not mix with DOT 3 or 4 fluid, which means all the old fluid has to be removed if switching to DOT 5 to prevent "slugs" of contaminated DOT 3 and 4 fluid from forming in the system. It is not recommended for any vehicle equipped with ABS because it contains a higher percentage of dissolved air that may cause foaming when the fluid is cycled rapidly.

      Although DOT 5 fluid does not mix with water, it can still be contaminated by entry of moisture into the system. Any moisture in a DOT 5 system, because it will not mix, will work it's way to the lowest point in the system. The calipers are typically the lowest and hottest point in the system. It is not unusual for caliper temperatures to exceed water boiling point under normal driving conditions. For this reason, we do not recommend DOT 5 fluid for high performance use.




    How do I know when my car really needs a brake job?
    You need a "brake job" when your brake linings are worn down to the minimum acceptable thickness specified by the vehicle manufacturer or the applicable state agency in areas that set their own requirements. The only way to determine if new linings are required, therefore, is to inspect the brakes.

    You may also need a brake job if you're having brake problems such as grabbing, pulling, low or soft pedal, pedal vibration, noise, etc., or if some component in your brake system has failed. But if the problem is isolated to only one component, there's no need to replace other parts that are still in perfectly good working order.

    There is no specific mileage interval at which the brakes need to be relined because brake wear varies depending on how the vehicle is driven, the braking habits of the driver, the weight of the vehicle, the design of the brake system and a dozen other variables. A set of brake linings that last 70,000 miles or more on a car driven mostly on the highway may last only 30,000 or 40,000 miles on the same vehicle that is driven mostly in stop-and-go city traffic.

    As a rule, the front brakes wear out before the ones on the rear because the front brakes handle a higher percentage of the braking load -- especially in front-wheel drive cars and minivans. So many service facilities advertise $59.95 brake job "specials" that replace the linings on the front brakes only. Doing the front brakes only is okay and can save you money as long as the rear brakes are in good condition. But if the rear brakes need attention, they should be relined too.

    One of the problems with the brake specials you see advertised in the newspaper is that the price is very misleading. A person typically goes in expecting to spend $59.95 for a brake job, but usually ends up spending considerably more because the brakes need more than the minimum amount of work to restore them to like-new condition. The price of a brake job depends entirely on the work that needs to be performed. So any advertised special is not a firm price, but only an estimate of the least amount of money it might cost you to get your brakes fixed. A price should not be quoted until after the brakes have been inspected. Then and only then can an accurate determination be made of the parts that actually need to be replaced.




    Is it always necessary to resurface the rotors and drums when the brakes are relined?
    No. The rule here is resurface when necessary, don't resurface when it isn't necessary. If the rotors and drums are in relatively good condition (smooth and flat with no deep scoring, cracks, distortion or other damage), they do not have to be resurfaced. Resurfacing unnecessarily reduces the thickness of these parts, which in turn shortens their remaining service life.
    According to the uniform inspection guidelines developed by the Motorist Assurance Program (MAP), "friction material replacement alone does not warrant rotor reconditioning." Whether or not the rotors or drums need resurfacing or replacing depends entirely on their condition at the time the brakes are relined. Even so, many mechanics prefer to resurface rotors and drums when relining the brakes to restore the friction surfaces to "like-new" condition and to minimize any chance of brake squeal.

    A number of things must be considered to determine whether or not resurfacing is really necessary:
    • Surface condition. The most important criteria. Scoring, pitting or other minor surface imperfections should be cleaned up by resurfacing. Resurfacing is also recommended if the brakes have been noisy. If a rotor or drum is cracked, however, it must be replaced.
    • Lateral runout on rotors. This must be measured with a dial indicator against the face of the rotor. If rotor wobble exceeds OEM specs, reindexing it on the hub (if possible) may help reduce runout. But a better solution here is to resurface the rotor on the vehicle using a special "on-car" lathe. This type of equipment cuts the rotor true to its axis of rotation.
    • Rotor warpage. Variation in the thickness of the rotor or uneven spots on either rotor face will cause the brake pedal to pulsate or shudder when the brakes are applied. Flatness can be checked by placing a straight edge against both faces of the rotor. Thickness must be checked with a micrometer at six or more points around the rotor.

      If parallelism between rotor faces exceeds OEM specs (generally about .005 in.), or if the rotor is warped or has hard spots (which are often discolored blue or black), the rotor should be resurfaced or replaced. Hard spots that develop from overheating or uneven tightening of lug nuts can create raised areas on the surface that often extend below the surface. The metallurgical changes in the rotor often cause the hard spots to return after a few thousand miles so replacing the rotor may be the best long-term fix.
    • Rotor thickness and drum diameter -- If a rotor is close to or at the minimum thickness specification (which is stamped on the rotor or may be found in a brake service reference book), it is too thin to be resurfaced and must be replaced. The same goes for drums, except the critical dimension here is the drum's inside diameter (the maximum or discard diameter spec is stamped on the drum or listed in a reference book).

      When a rotor or drum is resurfaced, the least amount of metal possible should be removed to maximize the remaining service life of the part. It's also a good idea to sand rotors after they've been turned with #120 to #150 grit sandpaper to create a smooth, nondirectional or crosshatch finish. Sanding helps "plateau" the surface by knocking off the sharp peaks left by a lathe. Some brake lathe manufacturers say this final step isn't necessary because their equipment leaves such a smooth finish. Maybe so. But sanding is still a good way to ensure proper pad seating and minimize the chance of noise with semi-metallic pads.

      Finally, rotors and drums should always be cleaned with alcohol or brake cleaner before they are reinstalled. Resurfacing leaves a lot of metallic debris on the surface which can embed itself in the new brake linings and cause noise problems. Even if the rotors or drums have not been resurfaced, cleaning is recommended to remove dirt and grease (which can contaminate new linings and cause uneven braking or grabbing).




    What about Brake Pads and Brake Shoes?
    Brake pads and brake shoes are composed of a friction lining material mounted onto metal backing plates. Brake linings are designed to have a specific coefficient of friction. The linings contact the drums and discs, create drag, and thereby retard the speed of the vehicle. The lining material is designed to wear down faster than the rotors and drums they rub against, so that they are the only part that usually has to be replaced. Usually, when worn out pads and shoes are replaced, the drums and rotors are re-machined (a small amount of metal is removed from their surfaces) so that the brake shoes and pads will "break in" properly.

    Because of intense friction and heat produced in braking, brake linings were first composed of heat-resistant asbestos compound. When it was discovered that breathing dust containing asbestos fibers can cause serious bodily harm, asbestos pads were replaced with other types. Until recently, three basic types of materials have been used in brake linings: (1) non-asbestos organic, which is usually made from filler materials and high temperature resins; (2) metallic; and (3) semi-metallic, which are composed of finely powdered iron or copper, graphite, and small amounts of inorganic filler and friction modifiers. The first and third types of brake lining are used for conventional brake service. Under extreme braking conditions (sports cars, ambulances, police cars), the metallic type of linings are used, because they provide more constant frictional characteristics (reduced brake fade) than the other two. Organic pads and shoes wear down the rotors and drums less than semi-metallic or metallic pads, but also wear down quicker themselves, requiring more frequent replacement. Also, organic linings tend to have less "bite" and their braking performance at high temperatures is less effective.This makes them more suitable for low speed commuting in light vehicles.

    Most pads and shoes have "wear indicators" built into them, or into the hardware which holds them in place. The wear indicators cause a squealing noise when the linings wear down to the level of the indicator. Mechanical wear indicators (small metal tabs) allow the driver to know when their brakes are needing replacement before serious damage occurs. When the pads or shoes wear out completely (past the wear indicators) and the backing plates contact the drums or discs for extended periods of time, the damage which results can require replacement of the rotor or drum, which is MUCH more expensive than the shoes and/or pads! Some advanced braking systems have electronic wear indicators built into the linings, which allow the driver to be warned by a light on the dash.









    What is the difference between Hawk HPS (High Performance Street) pads and the HP Plus?
    The Hawk HPS compound is a low-dust, low-noise brake pad that is gentle on rotors and has a long life. The HP Plus pads offer more fade resistance, but will be a little harder on your rotors. We have gotten a lot of great feedback about these pads. They are popular among the Corvette drivers and other sports car enthusiasts.



    What about Brake Hoses and Brake Lines?
    The master cylinder is connected to each wheel by brake lines and hoses. Brake hoses are specially constructed flexible tubes with metal ends for transmitting fluid under extreme pressure. These hoses are used to connect the calipers to the metal brake lines, allowing the caliper to move when the wheel turns or goes up and down. The entire hydraulic system is filled with brake fluid, which is pressurized by the movement of the master cylinder's pistons. This fluid is very important. Always use only the recommended fluid.

    When you remove a wheel, these hoses are easily visible. If the hoses appear cracked or brittle, they should be replaced immediately. Close inspection of the brake hoses is a good way to prevent catastrophe!

    A typical upgrade from standard brake hoses is to Stainless Steel Braided Brake Hoses.Typical production car flex hoses are constructed from canvas reinforced rubber. They are adequate performers and work safely for a reasonably long time. These hoses do tend to expand or swell under pressure adding to "system flex" and a less firm "pedal feel". Over extended periods, the porous nature of rubber can admit moisture. Rubber tends to deteriorate and crack, increasing porosity and the risk of catastrophic failure.

    Stainless steel braided hoses, on the other hand, are made up of a teflon inner hose reinforced by a sheath of braided stainless steel wires. Teflon is impermeable and therefore excludes the entry of moisture. Possibly the most important feature is the strength of this type of hose construction. These hoses help to reduce "system flex" as they do not flex under system pressure and will never deteriorate.

    Brake lines are small steel tubes with special internal coatings to prevent rust and corrosion. These tubes connect to the master cylinder, and then run under the car to each of the wheels. At the wheel, a "brake hose" connects the brake line to the caliper or wheel cylinder. As the brake pedal is pressed, the master cylinder forces the brake fluid throughout the brake lines and into the wheel (or brake) cylinders. This pressure causes the slave cylinder pistons to move, forcing the shoes and pads against the drums and rotors to slow the vehicle.




    My brakes are squealing. Does that mean I need a brake job?
    Not necessarily. A certain amount of brake noise is considered "normal" these days because of the harder semi-metallic brake pads that are used in most vehicles. This type of noise does not affect braking performance and does not indicate a brake problem. However, if the noise is objectionable, there are ways to eliminate it.

    Brake squeal is caused by vibration between the brake pads, rotors and calipers. Pad noise can be lessened or eliminated by installing "noise suppression shims" (thin self-adhesive strips) on the backs of the pads, or applying "noise suppression compound" on the backs of the pads to dampen vibrations. Additional steps that can be taken to eliminate noise are to resurface the rotors and replace the pads.

    Some brands of semi-metallic pads are inherently noisier than others because of the ingredients used in the manufacture of the friction material. Strange as it may sound (pardon the pun), cheaper pads are sometimes quieter than premium quality or original equipment pads. That's because the cheaper pads contain softer materials that do not wear as well. For that reason, they are not recommended. Premium quality pads (for street use)should cause no noise problems when installed properly and will give you better brake performance and longer life.

    Conditions that can contribute to a disc brake noise problem include glazed or worn rotors, too rough a finish on resurfaced rotors, loose brake pads, missing pad insulators, shims, springs or antirattle clips, rusty or corroded caliper mounts, worn caliper mounts, and loose caliper mounting hardware. Drum noise may be due to loose or broken parts inside the drum.

    Most experts recommend new caliper and drum hardware when the brakes are relined, a thorough inspection of the calipers and rotors for any wear or other conditions that might have an adverse affect on noise or brake performance, and resurfacing the rotors (and drums) if the surfaces are not smooth, flat and parallel. If you hear metallic scraping noises, on the other hand, it usually means your brake linings are worn out and need to be replaced -- especially if your brake pedal feels low or if you've noticed any change in the way your vehicle brakes (it pulls to one side when braking, it requires more pedal effort, etc.).

    Some brake pads have built-in "wear sensors" that produce a scraping or squealing noise when the pads become worn. In any event, noisy brakes should always be inspected to determine whether or not there's a problem. And don't delay! If the pads have worn down to the point where metal-to-metal contact is occurring, your vehicle may not be able to stop safely, and you may score the rotors or drums to the point where they have to be replaced.




    I feel a pulsation or vibration in my brake pedal every time I stop. But the brakes seem to work fine. Is anything wrong?
    A pulsating brake pedal, which may be accompanied by a shuddering or jerky stop during normal braking, usually means a warped rotor or an out-of-round drum -- although it can sometimes be caused by loose wheel bearings, a bent axle shaft or loose brake parts. If the vehicle is equipped with ABS, however, some pedal feedback and noise is normal during panic stops or when braking on wet or slick surfaces. But you should not experience any ABS pedal feedback when braking normally on dry pavement.

    The faces of a disc brake rotor must be parallel (within .005 inch on most cars) and flat (no more than about .002 to .005 inches of runout) otherwise it will kick the brake pads in and out when the brakes are applied, producing a pulsation or vibration that can be felt in the brake pedal as the rotor alternately grabs and slips. You can often see warpage in a brake rotor by simply looking at it. If the rotor has telltale glazed or discolored patches on its face, chances are it is warped. Measuring it with a dial indicator and checking it for flatness with a straight edge will confirm the diagnosis.

    Resurfacing the rotor to restore the faces will usually eliminate the pulsation (unless the rotor is bent or is badly worn and has started to collapse in which case the rotor must be replaced). But it may only do so temporarily because of metallurgical changes that take place in the rotor. Hard spots often extend below the surface of the rotor. Resurfacing will restore the surface, but the hard spot may reappear again in a few thousand miles as the rotor wears. For this reason, GM and others recommend replacing warped rotors rather than resurfacing them.

    Pedal pulsation caused by drum warpage isn't as common, but it can happen. A drum can sometimes be warped out-of-round by applying the parking brake when the brakes are hot. As the drum cools, the force of the shoes causes the drum to distort.

    What causes a rotor to warp? Over-torquing or unevenly torquing the lug nuts with an impact wrench is a common cause. For this reason, most experts recommend using a torque wrench to tighten lug nuts when changing a wheel. There are also special torque-limiting extension sockets called "Torque Sticks" that can be safely used with an impact wrench to accurately tighten lug nuts. But a plain impact wrench should never be used for the final tightening of the lug nuts because most provide no control whatsoever over the amount of torque applied to the nuts.

    Overheating can also cause rotors to warp. Overheating may be the result of severe abuse or dragging brakes. Defects in the rotor casting, such as thick and thin areas can also cause uneven cooling that leads to warpage. Hard spots in the metal due to casting impurities can be yet another cause.

    Finally, poor quality castings subjected to rapid "cool-down" after they were poured from molten iron will likely retain a degree of "molecular stress" which can be relieved as the rotor becomes hot. This stress relieving distorts the rotor. Better quality rotors are intentionally "stress relieved" by reheating and carefully controlling the cooling prior to machining and are more likely to provide trouble-free service. All of our Precision Brakes Company Custom Brake Kits contain "stress-relieved" rotors.




    I've heard that using a temporary spare will disable my ABS system. Is that true?
    Yes. On many cars equipped with ABS and a temporary spare, an electrical connector inside the trunk or luggage compartment is attached to the valve stem on the spare tire. If you have a flat tire and remove the spare, you have to unplug the connector. This tells the ABS system that the temporary spare is being used, causing it to temporarily disable itself.

    The reason why the ABS system shuts itself off when the temporary spare is in use is because the spare tire has a smaller diameter and narrower tread than a standard tire. This causes the tire to rotate somewhat faster than the other tires, and to brake differently. Were the ABS system not disabled, the difference in wheel speed and braking friction caused by the temporary spare would probably cause the ABS system to kick in unnecessarily when the brakes are applied. So disabling the ABS system prevents this from happening.

    The important thing to remember here is to reconnect the ABS connector to the spare tire when it is returned to the trunk. If this is not done, the ABS system will remain disabled and unable to prevent skidding when braking on wet or slick surfaces.




    My brake pedal slowly sinks to the floor when I hold my foot on it. What's wrong?
    You either have a fluid leak in your brake system or your master cylinder is defective. Either way, your brakes need immediate attention.

    If the brake warning light is on, you most likely have a fluid leak. Your vehicle may not be safe to drive in this condition! You should have the brakes inspected as soon as possible to determine where the fluid is leaking (usually a hose, brake line, brake caliper or wheel cylinder) so the necessary repairs can be made.

    If the brake warning light is not on, it does not necessarily mean you do not have a leak. The warning light only comes on when there's been enough fluid loss to create a pressure differential between the two sides of the hydraulic system that actually apply the brakes. The brake system is divided into two hydraulic circuits. On most rear-wheel drive vehicles, it is divided so one circuit applies the front brakes and the other applies the rear brakes. On front-wheel drive cars, the system may be split diagonally. One circuit works the right front and left rear brake, and the other works the left front and right rear brake. This is done for safety purposes so if one circuit loses all its brake fluid and fails, the vehicle will still have one remaining circuit to apply two wheel brakes.

    A quick way to check for leaks in either circuit is to simply check the fluid level in the master cylinder reservoir. The reservoir is divided into two chambers (one for each brake circuit). If one chamber is unusually low or empty, there's a leak somewhere in that circuit. The brakes should then be inspected to check for fluid leaks. Wet spots around hose or line connections, or fluid leaking from a disc brake caliper or drum wheel cylinder would indicate a serious problem that needs immediate attention.

    If the brake warning light is not on and there are no apparent leaks, then the master cylinder may be worn or leaking internally allowing the pedal to slowly sink when pressure is applied to it. This type of condition will be most noticeable when holding constant pressure against the brake pedal at a stop light. If the pedal sinks or requires pumping to keep the car from creeping ahead, the master cylinder needs to be replaced.

    On some vehicles with rear-wheel antilock brake systems (ABS), it's also possible that a leak in the ABS unit may cause a similar sinking pedal condition.




    My brake pedal is low when I step on it, but it comes up when I pump the brakes. Do I need new brakes?
    A low brake pedal that has to be pumped repeatedly to bring a vehicle to a stop may be due to a low fluid level, drum brakes that need adjustment or air in the lines. It usually has nothing to do with the condition of the brakes and certainly isn't necessarily grounds for a brake job. If the pedal feels "soft" or "spongy" instead of firm, there's probably air in the system. This will require "bleeding the brakes" to remove air from the lines, calipers and wheel cylinders.

    The first thing that should be checked is the fluid level in the master cylinder reservoir. If the level is low, there may be a leak somewhere in the hydraulic system that must be found and repaired. Adding fluid under these conditions will only cure the symptom, not the cause, and sooner or later the level will be low again creating a dangerous situation. So check for leaks around the master cylinder, wheel cylinders, brake calipers, rubber brake hoses and steel brake lines. Low fluid levels in drum brake systems can occur as a result of warn brake linings.

    If the fluid level is okay, the adjustment of the rear brakes should be checked next (assuming the vehicle has drum brakes in the rear -- if it has drums all the way around, check the front drums first, then the rear). The shoes should be close enough to the drums to produce just a hint of drag when the wheels are rotated by hand. An excess of slack probably means the self-adjusters are either frozen or fully extended.

    If adjusting the drum brakes fails to eliminate the low pedal, the wheel and drum will have to be removed so the adjusters can be freed up or replaced, and/or so the worn brake shoes can be replaced.

    If the vehicle has rear disc brakes, the adjusting mechanism in the rear caliper pistons that maintain the correct pad-to-rotor clearance may be corroded, frozen or worn out. In most cases, the piston assemblies cannot be rebuilt and must be replaced.

    If the fluid reservoir is full and the brakes are properly adjusted, but the pedal is low (or feels spongy), there is probably air in the brake lines. Air is compressible, so every time you step on the pedal, the bubbles collapse instead of transferring pressure to the brakes. The cure here is to bleed the brake lines following the factory recommended sequence.

    Brakes are usually bled in a specified sequence (always refer to a shop manual for the exact procedure for your vehicle). Usually the rear brakes are bled first, then the ones up front on most rear-wheel drive cars and trucks. But on vehicles with diagonally split hydraulic systems, the brakes are bled in opposite pairs (right rear and left front, then left rear and right front). Following the proper sequence is important so air doesn't remain trapped in the lines. On late model GM and Ford cars with quick take-up master cylinders, the quick take-up valve takes about 15 seconds to reseat after the brake pedal has been depressed. If the pedal is pumped too quickly while manually bleeding the system, you may never get the pedal to firm up. Most professionals use pressure bleeding equipment to bleed the brakes because it is faster and easier.




    Do you have a recommendation for my SUV? The "brakes" are one of my few complaints.
    Yours is a common complaint and one that is not easy to remedy. Many SUVs suffer a basic brake design failure.

    Our guess is that it warps rotors at a rapid rate, you have them machined and replaced regularly, right? If this is the case, a high quality rotor may increase the service interval, but there's no guarantee because the rotors are overtaxed. If brake fade is a bigger problem, we could possibly supply a brake pad which will operate at higher temperatures and also offer rotors which are gas slotted to alleviate pad outgassing issues which can cause fade.

    The real solution is to increase the rotor diameter and mass, then add a larger caliper to increase the available clamping force. This is the only way to guarantee a viable brake system. The down side is the cost. First your wheels will have to be large enough in diameter to clear the larger system which will involve an investment if you are currently running the stock rims. If the stock rotors are a little more than 12" in diameter, an increase to 13" or 14" will offer reasonable results but will require 17" or 18" rims respectively.



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