Editing Brakes

{{develop1}} ==Preamble== This article will introduce you to brakes and the components that are involved as they apply to the automotive world. We will try to break down the brake system in to its proper categories so that you can understand them better and apply that knowledge. Many people ask frequently about braking systems, and what is better and what is usable. Everyone wants to go faster, handle better, braking is often ignored, mainly due to the price of major upgrades. After research and some experience most people will find that big brake kits, slotted, cross-drilled rotors have not made a huge dent in 60-0 or 70-0 stopping distances. In this article we will look at what ''is'' important in stopping a vehicle and what factors are involved. The reader should remember the concepts behind braking in this article. These concepts are universal: no matter what vehicle we talk of, improving stopping distance is a matter of applying physics based on vehicle parameters, driving habits and driving conditions. ==Caliper types== In general, there are two types of calipers, floating and fixed. ===Floating=== Floating calipers usually have one or two pistons located on the inboard side of the caliper and they squeeze the pads against the turning rotor using a thru-bolt as a guide for the pads. ===Fixed=== As the name implies, the caliper does not move. They have the pistons on both sides of the rotor, the equal force applied by the pistons centers the caliper without it needing to float. There may be as many as six pistons that apply pressure to the pads. They are usually a high performance type of brake, i.e. [http://www.baer.com/ Baer brakes]. ==Rotors== Slotted and cross drilled rotors help cool the brake system with airflow across them and the calipers. Without sufficient airflow, having slotted or cross drilled brake rotors is hardly more effective than standard ventilated discs. The slotted/drilled rotors do help with brake pad out-gassing; when the pads reach their operating temps or higher they start to give off gas as they wear and the slots and/or holes gives this gas a place to go so it doesn't build up between the pad and rotor, causing a loss of brake effectiveness. {| |[[Image:Disc_vented.jpg|thumb|center|700px|Typical vented rotor‎]] |[[Image:Slotted_vented.gif|thumb|center|500px|Slotted and vented rotor]] |[[Image:Slotted_x_drilled.jpg|thumb|center|300px|Slotted and drilled rotors‎]] |} The downside to cross drilled rotors is reduce surface area, a decreased co-efficient of friction and they might be more prone to warping or cracking if not done correctly. The advent of carbon metallic friction materials with their increased temperature stability and friction coefficient characteristics can mean slotted/drilled rotors are needed less than before. Typically, in original equipment passenger car applications these holes are cast then finish machined to provide the best possible conditions to resist cracking in use. But they still may crack eventually under severe circumstances. With a properly designed brake system, drilled ventilated discs can operate cooler than non-drilled non-ventilated discs, due the higher airflow rates through the vents from the supplemental inlets and increased surface area of the holes. The airflow is into the hole and out through the vent to the OD of the disc. If discs are to be drilled, the external edges of the holes must be chamfered or radiused. ==Drum brakes== [[Image:Drum_brake.gif‎|frame|none|Internal drum brake illustration]] ==Brake system== A high performance brake system will often use specific brake fluid for the application, stainless steel hard brake lines, teflon lined braided flexible brake lines, air ducting and venting, along with all the other necessary items to aid in controlling brake component temperatures. The picture below shows a typical hotrod brake system which utilizes an adjustable proportioning valve, residual pressure valves, a master cylinder, and a vacuum brake booster. This is an under-floor brake system setup. [[Image:Hot_rod_brake_system.jpg|border|450px]] ===Proportioning valves=== An adjustable fluid valve that allows you to set the amount of pressure being applied to a wheel cylinder by increasing or decreasing the fluid by way of a adjusting valve. ===Residual pressure valves=== A one-way valve that allows fluid to flow through it at any pressure, but limits the amount of return pressure to a certain amount by way of a spring loaded check-valve. Usually comes in 10 psi (red color) for drum brakes and 2-3 psi (blue color) for disc type brakes. These valves are mainly used in under-floor systems where the calipers are higher than the master cylinder reservoir and to compensate for the return spring tension in drum brake systems. RP valves eliminate excessive brake pedal travel in both systems ===Master cylinders=== A dual reservoir master cylinder (MC) is used in any modern vehicle and should be used on older vehicles that had single reservoir master cylinders. Usually a drum brake master cylinder will not work for disc brakes because the bore size is too small, and the drum brake MC may have a built in residual valve. ====Power master cylinder diameter and pedal ratio==== Most times, a master cylinder for a power brake system should have a pedal ratio of about 4:1 when using a master cylinder bore diameter of 1-1/8". ====Manual master cylinder diameter and pedal ratio==== Most times, a master cylinder for a manual brake system should have a pedal ratio of about 6:1 when using a master cylinder bore diameter of 1". As a rule of thumb, a pushrod attachment point on the brake pedal about 1" above where the power brake attachment point was (closer to the pivot point) will be about right for a manual brake system. If using a bore larger than 1" on a manual system, the brake pedal effort can become very high. [[File:Pedal ratio1.jpg|thumb|700px|left|Pedal ratio guidelines from mpbrakes.com]] <br style="clear:both"/> ===Brake boosters=== In most cases the vacuum required to operate a power brake vacuum booster should be at least 18" for best results. In most cases anything less than 14" of vacuum will not be enough. Using a vacuum reservoir is not a very good substitute for inadequate vacuum. In cases where there's not enough vacuum, a vacuum pump may be used, or the system changed to manual brakes. If space is a problem, a dual diaphragm booster might be enough smaller in diameter to help, as long as the booster has sufficient pressure to do the job. ====Some guidelines from MP Brakes:==== A midsize GM car with disc brakes in the front and drum rear brakes will require at least 900-1,000 psi to the wheels to lock them up. The pressure output of the booster is directly proportional to its diameter, the larger the booster the greater the power assist. The following assumes 18 in/Hg of vacuum at idle, and 120 psi of pedal force: *Four wheel disc = 9" dual diaphragm (1200 psi) *Front disc/rear drum = From the 9" dual (1200 psi) down to a minimum of a 7" dual (900 psi) *The 8” dual diaphragm booster makes 1,000 psi *9” single diaphragm 900 *7” dual diaphragm 900 *7” single diaphragm 800 ===Brake lines and fittings=== [[File:SM_brake_fitting01.jpg|border|300px]] ==Resources== *[[url=http://www.crankshaftcoalition.com/wiki/Brakes#Brake_boosters][/url] Technical support] from MP Performance Brakes. Includes FAQ, Configurations, Troubleshooting, and Installation Guides [[Category:Brakes]] [[Category:Undeveloped articles]]

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