AP Racing ⨉ Essex CP9660 Radi-CAL Competition Front Brake Kit for RZ34 Nissan Z

AP Racing ⨉ Essex CP9660 Radi-CAL Competition Front Brake Kit for RZ34 Nissan Z

Redefine your RZ34 Nissan Z’s front braking prowess with the AP Racing ⨉ Essex CP9660 Radi-CAL Competition Front Brake Kit. Despite its larger size, this kit lightens your vehicle by approximately 25 unsprung lbs., compared to OEM brakes, enhancing handling and responsiveness. Carefully engineered to clear OEM 19″ wheels without a spacer and to fit inside many 18″ wheels, this kit incorporates the trailblazing AP Racing CP9660 Radi-CAL calipers. These are paired with 372x34mm, 72 vane AP Racing J Hook 2-piece floating discs, with each component meticulously designed to withstand the intense heat of prolonged track sessions. The pistons are expertly sized for a seamless integration with your OEM master cylinder and ABS system. Whether paired with your OEM rear brakes or the AP Racing by Essex Rear Brake Kit, this front brake kit delivers a substantial upgrade to your vehicle’s track performance.

Radi-CAL

• With its patented Radi-CAL asymmetrical brake caliper design, AP Racing has significantly advanced the field of brake technology. This innovative design employs state-of-the-art technologies, such as Computer Aided Design (CAD) and Finite Element Analysis (FEA), enabling the creation of uniquely designed calipers that go beyond traditional norms. Radi-CAL calipers, celebrated as the zenith of brake caliper technology, employ a distinctive and organically-shaped design that heralds a new era of innovation. Introduced in 2007, they have consistently redefined expectations, demonstrating their superb performance on numerous professional motorsport race tracks. With an impressive tally of victories, Radi-CAL calipers have indelibly marked their presence as a transformative force in brake performance.
• Benefits of the Radi-CAL Design
  • Significant Stiffness Enhancement – The Radi-CAL calipers demonstrate an impressive improvement of over 30% in both static and dynamic stiffness compared to conventional calipers. This significant enhancement in stiffness minimizes deflection under load, resulting in superior pedal feel and modulation, uniform pad wear, and extended caliper service life.
  • Substantial Weight Reduction – Through the elimination of unnecessary caliper mass, the Radi-CAL design effectively reduces the overall weight of the caliper, despite the notable increase in stiffness.
  • Optimized Airflow – The Radi-CAL calipers are meticulously engineered to optimize airflow, facilitating efficient circulation of air around and through the caliper. This enhanced airflow enables superior heat dissipation and cooling, thereby elevating overall brake performance.
  • Efficient Packaging – With its asymmetric caliper profile and internal fluid porting, the Radi-CAL caliper is purposefully designed to fit into compact spaces with efficiency. This thoughtful design allows for more flexible installation options without compromising performance.

CP9660 PRO5000R Calipers – The Everyman Radi-CAL

• After eight years of development, multiple design iterations, and advancements in manufacturing techniques, the Radi-CAL has finally evolved into a practical solution suitable for racers and enthusiasts of all levels and budgets. While many products claim to have racing origins, the Pro5000R calipers undeniably possess a genuine racing pedigree. Directly descended from the current generation of F1 and Sprint Cup calipers, they stand out from the ordinary because they are anything but ordinary. These calipers epitomize pure racing design, with an elegant, minimalist aesthetic that delivers brutal effectiveness. While they embody the past Radi-CAL design philosophy, they also incorporate exceptional new features that enhance practicality, convenience, and appeal. In essence, they are the lightest, stiffest, and most technologically advanced brake calipers ever accessible to the average enthusiast.
• Traditionally, these intricate calipers were machined from proprietary aluminum alloy billets. However, the process of machining away all that material to achieve the final form was time-consuming and expensive. Consequently, the price of these calipers has historically been prohibitive for the average club racer, time-trialer, or HPDE participant. Fortunately, the Pro5000R calipers utilize a new drop-forging technique that has significantly reduced manufacturing costs and, subsequently, the entry price. This development has made this incredible technology accessible to a wider audience.

Radi-CAL = Massive Dynamic Stiffness Increase

• Over the years, several strategies have been employed to reduce the size of brake calipers while maintaining sufficient stiffness. These strategies encompassed robust caliper bridge designs, two-piece calipers with steel through-bolts, the utilization of exotic materials such as Beryllium and MMC, the shift from casting to forging, and the adoption of monobloc designs. These innovations aimed to make calipers lighter, smaller, and stiffer. However, the traditional rectangular, boxy shape remained the widely accepted standard for calipers.
• AP Racing has challenged this notion, questioning the efficiency of the rectangular box design for brake calipers. They have demonstrated that the conventional design is suboptimal. As a caliper clamps brake pads against a spinning disc, a significant tangential friction force is generated between the pads and the disc. This force pulls the caliper strongly towards the spinning disc. The caliper resists this force through the rigid mounting points on the spindle.
• During braking events, the dynamic load exerted on the caliper causes it to twist or deform into a parallelogram shape. AP Racing recognized the significance of this dynamic force and specifically designed the Radi-CAL caliper to address it. Unlike traditional calipers that were developed without direct consideration of the forces they would encounter, the Radi-CAL caliper was intentionally designed around the forces generated during braking.
• The Radi-CAL caliper optimally distributes its body mass along a diagonal axis, rather than concentrating it solely at the ends of the caliper. This design allows the caliper mass to better support the forces acting on it during braking, rather than relying solely on an empty box structure. By redistributing the mass, significant overall weight reduction is achieved by eliminating non-essential, non-load-bearing material from the caliper body.
• WHAT DOES THE ABOVE MEAN FOR YOU, THE DRIVER? IT MEANS A SIGNIFICANTLY FIRMER BRAKE PEDAL WITH SUPERIOR MODULATION UNDER ALL CONDITIONS. IT ALSO MEANS MORE EVEN PAD WEAR WITH LESS TAPERING, AND A LONGER CALIPER SERVICE LIFE.

Radi-CAL = Ultra-Lightweight, Compact Design with High Airflow

• As mentioned earlier, the Radi-CAL design philosophy not only focuses on what is present but also on what is absent. The design deliberately redistributes caliper mass, creating voids in unconventional areas. This strategic removal of mass from the caliper body optimizes its overall size, resulting in an impressively lightweight and compact footprint. While competing six-piston calipers typically weigh between 9 to 12 lbs, the CP9668 weighs an astonishingly low 6.8 lbs.
• Essex’s approach to brake kit design has always prioritized efficiency, recognizing that anything larger than necessary adds unnecessary weight. The Radi-CAL aligns perfectly with this philosophy. Many brake packages in the market face the challenge of wheel fitment. They feature oversized discs and 12-piston calipers, which can pose difficulties when trying to fit them behind OEM wheels or lightweight alternatives. The goal is to save unsprung weight and enable the use of smaller, lighter wheels that are more easily accessible and cost-effective when paired with R compound tires. Properly designed components that prioritize performance eliminate the need for excessively heavy calipers. Concerns about stiffness resulting from mass reduction are unfounded. AP Racing’s Pro5000R calipers are not only lightweight but also exceptionally stiff, purpose-built for racing applications.
• A notable feature of the Pro5000R range is the positioning of the bleed screws and fluid pathways. The calipers incorporate internal fluid porting, with only two bleed screws located on the inner caliper half. This configuration minimizes the risk of damaging a bleed screw or crossover pipe during wheel changes. Additionally, it reduces the number of bleed screws that require attention during brake fluid replacement. The absence of external piping and bleed screws also allows for rounded outer corners, improving clearance with wheel spokes.
• Compared to traditional calipers, the design of the Pro5000R enables increased airflow between and around the pistons and brake fluid pathways. This enhanced airflow contributes to better overall system operating temperatures, resulting in improved performance and durability.

Two-Piece, Drop-Forged Caliper Body

• Calipers have traditionally been crafted through machining a single, solid block of exclusive aluminum alloy, employing a design known as monobloc. With this design, the piston bores and piston seal grooves can only be machined using a right-angle machine tool that needs to be inserted into the caliper. Machining away all the material using specialized tools and multiple setups to achieve the final shape is a laborious and costly process. As a result, monobloc Radi-CAL calipers have been priced beyond the reach of the average club racer, time-trialer, or HPDE participant. However, the advent of a novel two-piece drop-forging process has turned the Pro5000R caliper into a reality. This innovative manufacturing technique allows conventional machine tools direct access to the piston bores, resulting in a significant reduction in production time and cost while still upholding an exceptionally rigid structure.

Hard Anodized Finish

• One noticeable drawback when examining typical aftermarket calipers is their finish. Most aftermarket calipers are coated with paint, whether it’s red, black, or gold. This painted finish is primarily intended for aesthetic purposes and to protect against corrosion in harsh winter conditions. However, when used in a track environment, painted calipers are prone to chipping, flaking, fading, color shift, and general degradation within a relatively short period of time. In some cases, OEM calipers can even change from their original color to an unsightly shade of brown after just one weekend of track use. While some enthusiasts may wear this as a badge of honor, the appearance of the calipers is compromised. More importantly, the paint particles can end up in unwanted places, which we will discuss shortly.
• Why does this occur? The answer is heat. Paint and powder coat finishes are not adequately equipped to handle the high temperatures experienced on the track. Powder coat finishes are particularly susceptible to issues such as shrinkage. When the caliper heats up, the powder coat layer expands and grows. However, when it cools down, the powder coat may not shrink in proportion to the caliper body, resulting in a loose and fragile finish that eventually cracks and falls off.
• Paint can also face similar issues depending on the application process. If you were to compare several aftermarket calipers from the same manufacturer, you would likely notice slight differences in the painted finish. Some calipers may have a thicker coat, others may have a thinner coat, and there might be slight variations in shades of red or other colors. Painting is an art form that requires precise control of the environment. Without proper control, variations in the finish are inevitable. A thick coat of paint can make the caliper look soft around the edges and is more susceptible to cracking and chipping, similar to powder coat. Conversely, insufficient paint coverage leads to an uneven appearance and inadequate protection for the underlying aluminum. Additionally, both paint and powder coat undergo significant color shift when exposed to heat. Red can become maroon or black, gold can turn brown, and black simply becomes less appealing.
• The calipers used in the Essex Radi-CAL Competition Kits have been specifically designed to be ultra-lightweight, rigid, and durable under all track conditions. The finish on these calipers is achieved through a process called hard anodizing, which is exceptionally well-suited for track use. When raw aluminum interacts with oxygen in the air, it naturally develops a hard surface film that prevents further degradation. This natural process is referred to as oxidation, similar to rust. The anodizing process takes advantage of this natural phenomenon and enhances it by creating an extremely tough protective layer of aluminum oxide. This is achieved by passing an electrical current through an acid bath and dyeing it to achieve the desired color. If you’d like to delve deeper into the process, feel free to search for more information online.
• The result is a finish that is significantly more suitable for track use compared to paint or powder coat. Anodizing creates a uniform and highly abrasion-resistant surface, ensuring that if you accidentally hit an anodized caliper with a wrench while bleeding the brakes, the finish won’t easily chip off. While anodized calipers may still experience some color shift, it requires much higher temperatures to trigger such changes, and the shifts are not as dramatic. Most importantly, bits of anodizing won’t stick to the sides of the pistons, addressing the issue of unwanted particles interfering with the caliper’s operation.

Ventilated, Domed Back, Stainless Steel Pistons

• There is an ongoing debate regarding the use of aluminum pistons in track calipers, with some suggesting that the expansion rates of the pistons and caliper body should be the same when heated. However, this argument lacks substantiated evidence and validity. In contrast, reputable race caliper manufacturers worldwide exclusively rely on stainless steel or titanium pistons for their high-performance calipers due to their proven superiority.
• Stainless steel pistons excel in creating a thermal barrier that effectively minimizes heat transfer to the brake fluid, thus preventing the occurrence of a soft pedal caused by fluid fade on the track. This superiority has been consistently demonstrated across various levels of motorsport. While many aftermarket calipers make use of pressed aluminum pistons, the Pro5000R calipers utilize meticulously machined stainless steel pistons, despite the higher associated cost.
• In order to enhance piston stiffness, AP Racing has implemented a domed shape at the back of the piston. Although this design element may appear small, it has received immediate and overwhelmingly positive feedback from professional racing drivers. The domed back significantly increases stiffness, resulting in a noticeable improvement felt through the pedal. Consequently, this design has become the benchmark against which all other designs are measured.
• To further enhance heat resistance, the pistons are equipped with ventilation. The presence of air gaps around the edges of the piston facilitates additional air circulation, contributing to the cooling process around the pistons. These features work together to effectively slow down and repel the influx of heat into the brake fluid, effectively preventing issues such as brake fluid boiling and fade under demanding conditions.

Anti-Knockback Springs

• AP Racing calipers feature stainless steel pistons with integrated anti-knockback (AKB) springs, which may come as a surprise to some. However, these springs play a vital role in addressing a common issue known as knockback. If you’ve ever experienced your brake pedal dropping after a series of S-turns when entering a brake zone, you have encountered knockback, which can be unsettling. Professional drivers often lightly tap their brakes before a brake zone to counteract this phenomenon.
• Knockback typically occurs with fixed calipers and is a result of the wheel, hub, and bearings deflecting during cornering. This deflection causes the brake disc to move out of sync with the caliper and brake pads. As the disc deflects, it pushes the brake pads apart, causing the caliper pistons to retract into their bores. However, the piston seals lack sufficient tension to fully return the pistons to their original position, leading to slack in the system. When you apply the brake pedal, it continues to drop until the slack is taken up.
• To mitigate knockback, anti-knockback springs are incorporated into AP Racing calipers. These springs exert tension on the backside of the pistons. When the disc deflects and makes contact with the pistons, the springs push the pistons back into their proper position, reducing the slack in the system. As a result, there is less pedal drop and a more confident braking experience, especially when approaching heavy brake zones.
• The inclusion of lightweight AKB springs does not have significant downsides as long as the caliper is designed to accommodate them. Specifically, AKB springs do not cause increased drag or wear on the pads and discs, provided that the shape and material of the piston seals are appropriately considered.
• During driving, as the suspension compresses, the disc moves laterally, and the pads are slightly pushed away from the disc. It is helpful to think of the seals in the caliper as a spring or hinge attached to the side of the piston, rather than just a ring through which the piston slides. In AP Racing competition calipers, the groove where the seal resides features angles. As the pistons slide in or out, friction occurs between the outer piston wall and the seal, causing the seal to deform slightly.
• Before the piston starts moving through the seal ring, a certain amount of tension or friction must be overcome. This tension prevents the piston from dragging on the disc once the pistons are pushed back into the bores due to disc/suspension movement.
• The inclusion of AKB springs slightly increases the force required to push the pistons back into their bores compared to without the springs. Once the spring is compressed, it unloads and pushes the piston back to the ‘neutral’ position.
• When properly designed seals and springs are used, the goal is to keep the piston in the ‘neutral’ position, not pressed against the disc. The piston can still slide freely in either direction, but initially, some friction or tension must be overcome to initiate movement. The seal provides this initial friction to limit movement, and the spring adds additional resistance. Consequently, properly designed AP Racing calipers do not drag or cause unnecessary wear.

High Temperature, Low Drag Seals Without Dust Boots

• Essex frequently encounters a surprising question from potential customers regarding the maintenance and rebuilding of calipers in their kits due to the absence of dust boots on the pistons. This question puzzles them because it lacks intuitive reasoning. If a product is specifically designed to withstand the extreme high-heat conditions of track use, it should require less maintenance compared to brake components intended for low-speed and low-temperature street driving.
• There is often confusion between piston seals and dust boots. All calipers have seals, which are the small rubber rings inside the piston bores. Without these seals, brake fluid would leak around the pistons. OEM caliper seals are not designed to handle constant exposure to several hundred degrees without becoming brittle and leaking. However, Essex’s calipers utilize high-temperature seals identical to those used in NASCAR Sprint Cup, ALMS, DTM, and other professional racing series. These high-temp seals are less likely to become brittle and wear out under high-heat track conditions, resulting in significantly reduced replacement and servicing requirements.
• Most aftermarket calipers are designed for year-round road use and come with external dust boots, as shown in the example below. These rubber boots stretch as the pistons extend, aiming to keep contaminants out of the piston bore. While this concept seems appealing, Essex has observed instances where customers have burned through these boots in a single 20-minute track session. Once this occurs, the pistons are left with tattered and burnt rubber fragments that provide no benefits. Considering the boots are instantly destroyed during track use, it becomes unnecessary to include them in the design, eliminating the mess they create.

Simple Pad Change with Two Bolts

• When it’s time to change your brake pads, it’s understandable if you’re not particularly excited. However, with the Pro5000R calipers, this task will no longer be a chore. Say goodbye to struggling with hammers, punches, or pliers. AP’s bridge bolts can be easily removed using a 6mm hex wrench. Changing pads will now be quicker than ever before. In fact, you’ll spend more time removing the wheel than actually changing the pads. This means less time spent fussing around in the paddock and more time enjoying the thrill of driving.

Pistons Sized Specifically for Your Car

• The brake systems are carefully engineered to match the OEM brake torque on a specific axle by selecting the appropriate piston sizes. This meticulous design allows for the easy installation of front systems on stock cars without any adverse effects or negative impact on the ABS system. It eliminates the need to replace the stock master cylinder or the OEM rear brake system, providing a seamless integration of the brake components.

Lifetime Professional Reconditioning Service

• Essex holds the distinguished position as the official AP Racing caliper reconditioning center in North America. Their team comprises highly skilled service technicians who possess specialized expertise in the meticulous rebuilding of a significant number of AP Racing calipers annually. These calipers are relied upon by renowned teams in motorsport, such as those participating in NASCAR Sprint Cup and ALMS. This recognition solidifies Essex’s reputation as a trusted and accomplished entity within the industry.
• Removal and Shipping – To begin the service process, simply detach the calipers from your vehicle, drain and clean them thoroughly, and then ship them back to Essex.
• Hardness Testing – After disassembly, your calipers undergo Rockwell hardness testing to evaluate their fatigue and stiffness degradation. This testing helps us assess the extent of wear and determine whether the calipers should be rebuilt or replaced. Fatigued calipers can contribute to issues such as pad tapering, increased pad wear, seal leakage, and reduced pedal firmness.
• Ultrasonic Cleaning – Calipers that pass the hardness test undergo a comprehensive cleaning process in Essex’s advanced ultrasonic cleaner. This state-of-the-art cleaning method effectively eliminates all dirt, debris, and brake fluid, delivering superior results compared to traditional hand-cleaning methods.
• Inspection and Re-Assembly – All serviceable components of the caliper, including seals, abutment plates, pistons, and bleed screws, are meticulously inspected and replaced as necessary to ensure optimal performance.
• Cyclical Pressure Testing – Once the calipers are rebuilt, they undergo rigorous cyclical pressure testing on a specialized bench. This testing procedure ensures proper functionality and identifies any potential leaks that may occur only under specific pressure conditions.

Discs – AP Racing Competition J Hook

• The AP Racing J Hook discs featured in this system embody the pinnacle of endurance racing performance. These high-quality components are meticulously engineered to withstand the most demanding conditions imaginable. Recognized for their outstanding durability, these discs have an illustrious history in professional racing, securing numerous victories and championships in prestigious events like ALMS, Rolex, Grand Am, and more. With their exceptional performance and proven reliability, the AP Racing J Hook discs are the perfect choice for drivers seeking unmatched performance and enduring resilience in their racing endeavors.

Two-Piece Floating Design with Aluminum Hat

• When subjected to heat, iron brake discs, like most metals, undergo significant expansion. This expansion causes the disc to increase in diameter and circumference. One-piece disc designs face a challenge in accommodating this expansion. In the image below, imagine the disc being heated during track use. As the disc expands, the outer edges pull away from the center without any provision to accommodate this expansion. As a result, the disc edges become distorted and lifted, creating a phenomenon known as coning. Now visualize the disc mounted vertically in your caliper. Coning directly affects the contact between the brake pads and the disc, resulting in uneven wear, tapering, and a prolonged brake pedal.
• In contrast, two-piece discs are specifically engineered to address disc expansion when exposed to heat. This compensation is achieved by incorporating “float” into either the disc itself or the disc hat/bell. In the example below, the float is integrated into the disc. If you carefully examine the picture, you’ll notice that the mounting holes for the hat attachment bobbins are oblong in shape, rather than circular. These channels allow the hat mounting hardware to slide as the disc heats up and expands. This enables the disc to maintain its proper position within the caliper without distortion. This design approach effectively minimizes distortion, stress cracks, and pad taper, ensuring optimal performance and long-lasting durability of the braking system.

Mounting Hardware and Anti-Knockback Spring Clips

• Upon careful examination of the mounting hardware utilized in Essex’s Competition Kits, you will discover several often overlooked details that set them apart from inferior products. These components are purposefully designed and not mere generic bolts sourced from a local retail store. They are custom-made exclusively for Essex and AP Racing in the USA, and are the very same components used in professional racing applications.
• As mentioned earlier regarding the piston springs, knockback can pose a significant concern when driving on the track. To effectively manage the lateral movement of the disc, which can push the pistons back into the caliper, we incorporate anti-knockback spring clips at every alternate disc attachment point. For instance, a ten-bolt disc assembly would include five spring clips, while a twelve-bolt disc would feature six. These spring clips serve the purpose of maintaining alignment between the disc hat and the iron ring, while still allowing for radial expansion and floatation of the disc. Furthermore, they provide the added benefit of preventing any rattling or noise that may arise from the disc hat and iron disc assembly.

Hat Design

• In addition to their other notable benefits, floating two-piece discs offer the valuable advantage of minimizing heat conduction to the hubs and bearings. This reduction in heat transfer helps alleviate the wear and tear on these crucial components, ultimately contributing to their extended durability. The disc hats, an integral part of the assembly, are meticulously crafted from 6061 heat-treated billet aluminum, ensuring exceptional strength even under high-temperature conditions. To further enhance their performance, the hats undergo a hard anodized coating treatment. The choice of material and coating is specifically tailored to withstand the intense heat generated by the iron discs. Notably, the hats are designed with scallops on the underside, promoting effective heat dissipation along the outer face of the disc once they are installed.

Internal Vane Quantity and Quality

• The internal vane design of AP J Hook discs sets them apart from OEM-style discs and other aftermarket brands. Unlike the pillar vane designs commonly found in OEM discs, AP Racing discs take a different approach. Pillar vanes consist of interconnected posts or pillars that connect the two halves of the disc, causing turbulence as air passes through. This design prioritizes disc face stability and cost efficiency rather than efficient heat evacuation. Some OEM discs feature straight, non-directional internal vanes, which offer better airflow than pillar vanes but still fall short of the directional vanes found in AP Racing discs.
• AP Racing discs feature directional vanes that optimize airflow by spinning in a specific direction, maximizing the amount of air passing through the disc. Each pair of AP Racing discs is handed, meaning there is a unique left and right disc that cannot be interchanged. The vane orientation and shape are precisely engineered to promote smooth airflow and enhance cooling performance.
• Moreover, AP Racing discs surpass many aftermarket discs in vane count. While most aftermarket discs have 30 to 48 vanes, AP Racing’s J Hook discs boast a higher vane count, typically ranging from 60 to 84 depending on the application. The increased vane count allows for higher airspeed, improved heat transfer, reduced air recirculation between vanes, and diminished deflection at the disc face. Compared to OEM-style or competitor’s 48 vane discs, AP Racing’s 60+ vane discs demonstrate enhanced resistance to coning, distortion, and cracking. They also provide benefits such as reduced brake fade, minimized judder, more consistent pad contact, and extended service life.
• When comparing the internal vane design, one can observe the distinct features of the AP Racing J Hook disc. Notably, the AP Racing disc has a wider air gap between the disc faces, allowing for significantly increased airflow into and through the disc. The uniform and directional vane design further contributes to superior airflow performance.
• It is important to note that the majority of cooling air entering a brake disc originates from the backside of the discs, especially when brake ducts are used. A comparison between an OEM pillar vane disc, an OEM dual-cast disc (technically a two-piece disc), and the AP Racing J Hook disc highlights the differences. The AP Racing disc offers a clear and unobstructed path for cooling air to enter and flow through the disc, while OEM discs feature narrower inlet ports and potential obstructions that hinder the airflow. As a result, the AP Racing disc maintains significantly lower temperatures, reducing the likelihood of cracking and wear.

Exclusive AP Racing J Hook Slot Pattern

• When modifications like slots or holes are added to a brake disc, they can have an impact on heat transfer. These modifications create cool spots around the slots or holes when the disc heats up, which is not ideal. The ideal situation is for heat to be distributed evenly across the disc, allowing for effective cooling through airflow and radiation. The presence of cool spots can create areas of stress concentration and increase the likelihood of disc cracking. Furthermore, cool spots cause uneven distortion of the disc’s face, resulting in uneven pad deposits, vibrations, and judder.
• To address this issue, OEM discs avoid the formation of cool spots by leaving the disc face blank. While this reduces the risk of noise, vibration, and harshness (NVH), it also results in a decrease in pad bite and the tactile feedback felt through the brake pedal. On the other hand, many competitive aftermarket discs feature straight slots, which tend to create cool spots across the disc face between the slots.
• Extensive research and development testing conducted by AP Racing has led to the development of the J Hook design. This design creates a consistent pathway of evenly distorted material on the disc face. The hooks are strategically spaced around the disc’s circumference, from the inside edge where the hat attaches to the outer edge, with a slight overlap. This design promotes even heat distribution and distortion. In addition to reducing the risk of cracking, the even heating of the disc promotes the formation of a uniform transfer layer of pad material during the bedding-in process.

Complex Metallurgy Developed Through 50+ Years of Experience

• With a history spanning over five decades in brake component design, AP Racing has an impressive track record. Their components have been utilized in cars that have achieved victory in over 750 Formula 1 races, showcasing their expertise and reputation for reliability. In fact, on any given race weekend, you will find AP J Hook discs adorning 75% or more of the NASCAR Sprint Cup grid.
• Leveraging their extensive experience, AP Racing has developed a proprietary iron alloy known for its exceptional durability. This alloy is meticulously crafted to withstand the rigorous conditions it will encounter. Unlike OEM discs that prioritize cost-effectiveness and ease of production, AP Racing’s disc design objectives are distinct. Their unwavering focus is on delivering superior performance and unwavering reliability, ensuring that their products can endure the most demanding usage without compromising performance.

Caliper Brackets & Hardware

• The caliper brackets included in our kit are meticulously machined from heat-treated 6061 T6 billet aluminum, renowned for its exceptional strength and durability. To further enhance their resilience, these brackets undergo a rigorous hard anodizing process. We maintain the same high standards used in professional racing, utilizing aircraft-grade hardware that meets stringent quality requirements.
• One notable advantage of these brackets is their thoughtfully designed cutaway feature. This design enables precise fitting of various brake duct kits currently available in the market. The cutaway design ensures a secure and accurate fit, allowing for efficient cooling and airflow to the brakes, which is crucial for achieving optimal performance on the track.

Brake Ducting

• Essex recommends against using aftermarket brake ducts in conjunction with their Competition Brake Kits. Based on their extensive experience, they have encountered packaging limitations that make it extremely challenging to achieve effective airflow from the front of the car to the center of the brake discs. The narrow diameter of the duct hoses and limited space within the fender well often make it difficult to install properly-sized hoses that can provide adequate cooling. Furthermore, many aftermarket systems direct cooling air to incorrect locations, resulting in uneven cooling and temperature variations across the disc surface. These temperature differences can contribute to premature cracking.
• Moreover, the plates used to attach brake ducts at the wheel hub can inadvertently trap heat against the inner disc face, leading to overall increases in system temperatures. Taking these factors into consideration, Essex does not recommend using aftermarket brake ducts.
• If your vehicle is already equipped with OEM brake ducts that channel air into the wheel well or features air deflectors within the wheel area, it is acceptable to retain them. However, if you have installed an Essex Designed AP Racing Competition Brake Kit and notice higher-than-expected temperatures during operation, it is advisable to contact Essex to discuss potential solutions.
• It is crucial to avoid attaching any additional components between the caliper bracket and the suspension upright. Attaching ears or tabs from a brake duct system between the bracket and upright can misalign the caliper from its intended orientation, posing a serious risk of damage to the entire brake system or the vehicle. The bracket should be directly bolted to the upright as originally intended, without any objects sandwiched in between.

Spiegler Stainless Steel Brake Lines

• The Competition Kits include premium stainless steel brake lines, known for their outstanding quality. Spiegler lines excel in comparison to other options on the market, offering a wide range of features that deliver unparalleled performance benefits.

Disc Burnishing / Bedding Service

• Failure to properly prepare your brake discs before taking them on the track can result in issues such as juddering, vibration, and cracking. However, conducting these preparations at the circuit can be challenging as it consumes valuable practice time and may pose risks to nearby drivers. Additionally, on-track preparations lack consistency due to factors like changing weather conditions and traffic, making it difficult to achieve the necessary repeatability for optimal bedding and consistent performance.
• To address these concerns, Essex now offers a professional burnishing service to all customers. While initially exclusive to their racing clientele, this service allows individuals to have select Competition Brake Kits pre-burnished at Essex’s facility. With years of experience servicing discs for elite teams, Essex’s skilled technicians utilize an automated computer system and follow a rigorous regime based on feedback from top drivers and crews. This ensures the maximum efficiency of AP Racing disc brake sets.
• It’s important to note that the pads included in your kit will not undergo pre-burnishing. This means that the burnishing procedure for the discs can be performed with a pad compound of your choice, while still reaping the benefits of the procedure when using the pads provided in your kit.

Features

• Saves approximately 25 unsprung lbs. from nose of the car vs. OEM brakes, despite being considerably larger.
• Clears OEM 19″ wheels without a spacer.
• As large as possible while still fitting many 18″ wheels.
• Features AP Racing CP9660 Radi-CAL calipers.
• 372x34mm, 72 vane AP Racing J Hook 2-piece floating discs.
• Every component designed to resist the heat of extended track sessions.
• Pistons sized properly to allow for seamless integration with OEM master cylinder and ABS system.
• Designed to work with OEM rear brakes or the AP Racing by Essex Rear Brake Kit.

What’s In The Box

• One pair AP Racing CP9660 Radi-CAL Pro5000R six piston calipers.
• One pair 372x34mm AP Racing CP7177, 72 vane, J Hook racing discs, with fully floating 6061 hard anodized aluminum hats, and attachment hardware.
• One pair caliper mounting brackets and hardware.
• One pair Spiegler Stainless Steel Brake Lines with abrasion resistant coating.
• Detailed installation instructions.
• Brake pads are NOT included with this system.
  • Selecting the ideal racing brake pads is a matter of personal choice. Unlike other manufacturers who include subpar pads in their brake kits, Essex adopts a different approach. They have eliminated the cost of pads from their system, allowing customers to have the freedom to choose the brake pads that align with their preferences. This ensures that you can customize your brake setup to suit your specific needs without incurring any unnecessary expenses. When you purchase this kit, you have the option to select one set of front pads at a significant discount compared to the regular retail price. This empowers you to curate your brake system according to your desires while enjoying valuable savings.
  • DS1.11 – The DS1.11 brake pad is renowned for its performance in endurance racing compounds. It exhibits a moderate friction coefficient (mu) compared to the 3-12 pad, necessitating more pedal pressure. As temperatures rise, the DS1.11 delivers decreasing torque, enabling enhanced control with street tires. Although its lifespan may be slightly shorter due to its less aggressive interaction with discs, it boasts remarkable resistance to high temperatures. The DS1.11 is highly regarded for the feedback it provides, offering excellent fade resistance in endurance racing conditions.
  • DS2500 – While dedicated race pads generally offer superior performance on the track, the DS2500 brake pad stands out as a remarkable hybrid option suitable for both street and track use. It delivers moderate bite and impressive resistance to fading, while also maintaining manageable levels of dusting and noise compared to other street pads. In certain cases, slight squealing may occur with specific vehicles when used in its intended role. If your driving needs encompass high-speed driving, canyon runs, or occasional light track use with road tires, the DS2500 is hard to beat.
  • DS3.12 – Introduced in 2019, the DS3.12 represents the latest advancement in Ferodo’s impressive DS line of brake pads. It was specifically designed to meet the demands of modern sports cars with increased horsepower and aerodynamics. The DS3.12 offers exceptional performance for heavier vehicles that require stickier tires. Rigorous testing has demonstrated its remarkably consistent torque curve across a wide temperature range, surpassing other pad compounds available from various manufacturers. This means that braking remains consistent even in high-temperature conditions, minimizing wear rates without causing excessive damage to discs. With its revolutionary design, the DS3.12 sets a new benchmark and is expected to be recognized as the gold standard after comprehensive testing.
  • DSUNO – If you value the effectiveness of the DS1.11 brake pads but desire heightened stopping power, the DSUNO pads deserve your attention. While these pads may have a slightly shorter lifespan compared to the DS1.11, they offer a higher peak friction coefficient (mu) once they reach their optimal operating temperature on the track.
• Pad Tension Clips (frequently referred to as anti-rattle clips) are NOT included with these Competition Kits, but they do offer them as an option if you’re concerned about NVH.
  • The AP Racing calipers included in this system offer a significant benefit: they are engineered to accommodate brake pads from a wide range of manufacturers. Each manufacturer has its own specifications, resulting in slight variations in pad dimensions. As a result, pads from different manufacturers or batches may not fit snugly in the calipers. This can lead to some pads having excessive movement and generating noise during braking. To tackle this issue, Essex has developed the Essex Designed Pad Tension Kit. This kit is specifically designed to minimize pad movement within the caliper and reduce any resulting noise. By effectively addressing pad rattling, the Pad Tension Kit ensures a quieter braking experience. It’s important to note that each caliper requires one Pad Tension Kit, so a complete set would require two kits.

Applications

• 2023+ Nissan Z – RZ34
  • Application Type – Track

About AP Racing / Essex

In 1981, Michael Gue relocated to Essex, Connecticut, and established a business called “Essex Racing” to cater to the demand for British road racing cars and car parts in the United States. Having previously worked with similar materials in England, this experience likely influenced his decision to move countries and pursue business opportunities in America. Essex Racing quickly gained a loyal fanbase and became a trusted source for racing products.

In 1983, Essex Racing relocated to Atlanta, Georgia, seeking a warmer climate. The company continued to thrive as an importer of Van Diemen and Tiga formula and sports racing cars. Essex Racing actively participated in SCCA (Sports Car Club of America) and IMSA (International Motor Sports Association) road races, achieving success in both professional and amateur competitions throughout North America.

The growing interest in Essex’s racing vehicles led to an increased demand for related spare parts. To meet this demand, Essex Parts Services was established in 1992 as a dedicated business for selling these components. Over the next decade, Essex Parts Services became one of the leading distributors of racecar and stock car accessories in the United States.

In 1999, Michael Gue departed from the business, and Richard Martin and Ken Gordon took over Essex Parts Services. The company continued its success, leading to its relocation to Charlotte, North Carolina, in 2004 to better serve its substantial stock car clientele.

Throughout its history, Essex has remained attentive to its clients’ needs and has evolved accordingly. While the product range has significantly changed over the past 35 years, the company’s core principles have remained unchanged. Today, Essex stands as a prominent supplier of top-quality parts and services for road race, stock car, and high-performance street drivers across North America.