Brake trouble shooting

    SPONGY PEDAL
    1.Air in the brake system.
    2.Wrong size master cylinder.- .(too small).
    3.Calipers not mounted square to rotor.
    4.Calipers mounted equal to or higher than master cylinder.
    5.Pedal ratio too great.

    BRAKES DRAG
    1.Rotors warped.
    2.Tapered brake pads.
    3.Bad master cylinder.
    4.Residual pressure valve in system.
    5.Calipers not square to rotor.

    OSCILLATION FEED BACK
    1.Excessive rotor run out.
    2.Excessive front bearing clearance.
    3.Cracked rotors.
    4.Rotor faces not parallel.
    5.Pad material build-up on rotors.

    LOSE YOUR PEDAL DURING RACE
    1.Fluid boiling due to wet fluid or foot drag.
    2.Faulty master cylinder.
    3.Leak in caliper or hydraulic lines.
    4.Undersize brake system.

    CAR WON'T STOP / HAVE TO PUSH TOO HARD ON PEDAL
    1.Glazed pads or rotor.
    2.Master cylinder too large.
    3.Insufficient pedal ratio.
    4.Wrong pad material for your application.
    5.Frozen pistons in calipers.

BRAKE FLUID
Due to the extreme temperatures that high performance brake systems operate at, standard fluids are not recommended. KLRC recommends a dot 3 or dot 4 Hi-performance fluid with the dry boiling point of 466 degrees and a wet boiling point of 311 degrees. Dot 5 silicone fluid is not recommended because water will collect in your system causing lower boiling points and vapor lock. Dot 5 fluid is also a highly compressible fluid and will cause your pedal to feel spongy.

BLEEDING YOUR BRAKES
When bleeding your brakes, make sure the bleed screws are pointing up. Always start with the caliper farthest from the master cylinder. Have one person open the bleed screw while another person slowly depresses on the brake pedal. Close the bleed screw before brake pedal is released. Have someone keep checking the fluid in the master cylinder. Never let the level get low. Never put fluid drained out of the system back into the master cylinder.

REBUILDING CALIPERS
If you race on a weekly basis you should inspect your caliper seals for hardness or excessive wear at the beginning of the year and at least once during mid season. Bad seals could cause leakage or even frozen pistons.

BRAKE PADS
New brake pads require a bedding in process. This bedding in procedure starts by pumping your brakes at a very low speed to assure proper brake operation. then on a track make series of hard stops from moderate speed until some brake fade is felt. Park your car and allow brakes to cool completely.

Proper breaking in of pads and rotors will result in greater performance and longer wear.

Failure to properly bed in your pads could lead to friction material to flake and break up resulting in fast pad wear and pad loss, or could lead to overheating your pads and causing them to glaze over resulting in car not being able to stop.

Brake pads should be checked regularly. If pads are wearing evenly, the pads can be used almost down to the backing plate.

BRAKE ROTORS
New rotors just like pads need to be bedded in. This process is the same as the brake pads. Proper bedding will increase the rotor life and make it more resistant to thermal cracking. Any pulsation feel will go away after several repeated hard stops. Rotors are Blanchard ground to ensure the rotor is flat but sometimes hubs, bearings, or hats have run-out that cause the rotor to run-out. You can adjust the run-out by placing shims between the rotor and hub, or hat. Allowable run-out is .005-.008. Some run-out is acceptable if you are not experiencing brake drag, pedal pulsation or piston knock back.

CALIPER MOUNTING
Brake calipers need to be mounted square to rotor for proper performance. After caliper is mounted onto the bracket, have someone apply the brakes while the caliper is being observed. Only the pistons and pads should move.

MASTER CYLINDER
The bore size of the master cylinder influences the obtainable line pressure. Normally, when using only rear brakes a 7/8'' master cylinder is needed. If single piston front brakes are used in conjunction with rear brakes a 1'' master cylinder will work. For using 4 piston calipers front and rear a 1 1/8'' master cylinder is recommended.

BRAKE PEDAL RATIO
Improper pedal ratio is the most common cause of poor operation of brakes. The pedal ratio must be great enough to produce 1200 PSI system pressure under severe braking conditions. We recommend using a pressure gauge connected to the system to verify the maximum available pressure before running the car. Start with a pedal ratio of 6:1 and adjust if needed.

    DISC BRAKE MAINTENANCE
    1.Bleed each caliper on your race car.
    2.Replenish your brake system with fresh brake fluid.
    3.Check for leaks around pistons and fittings of each caliper.
    4.Check for leaks at any ''T'' fittings along the solid steel lines.
    5.Replace any pads that are worn down.
    6.Check for any burrs or dings on exposed area of piston to prevent damaging the internal seals
        during piston retraction.
    7.Make sure all wheel rotate freely.
    8.Check all bolts for secure tight fit.
    9.Blow away brake dust with an air hose from time to time.

RESIDUAL PRESSURE VALVES
Normally residual pressure valves are not recommended. However, in some cases when the calipers are mounted at the same level or higher than the master cylinder a 2 pound residual valve is necessary to prevent back-flow from the caliper to the master cylinder. If a residual valve is needed it should be plumbed just outside the master cylinder or as close as possible.

PROPORTIONING VALVES
A proportioning valve restricts pressure to a portion of the braking system, with this in mind the valve should be installed on the brake line in which pressure needs to be reduced. A typical street vehicle normally will use a proportioning valve in the rear line, due to most braking is done at the front wheels. A drag racing vehicle or any vehicle using a 3.5 front wheel normally will use a proportioning valve on the front line since most braking will be done at the rear wheels. An adjustable valve should be used so that you can tune the brakes to your particular car.