AP Racing ⨉ Essex CP9451 Radi-CAL Competition Rear Brake Kit for RZ34 Nissan Z & Z34 Nissan 370Z

AP Racing ⨉ Essex CP9451 Radi-CAL Competition Rear Brake Kit for RZ34 Nissan Z & Z34 Nissan 370Z

Experience the enhanced performance of your RZ34 Nissan Z and Z34 Nissan 370Z with the AP Racing ⨉ Essex CP9451 Radi-CAL Competition Rear Brake Kit. Despite the larger size of AP discs, which are 15mm larger in diameter and 10mm thicker, the kit maintains a similar weight to the OEM Sport Package setup. It is equipped with AP Racing CP9451 Radi-CAL four-piston calipers and retains the functionality of your OEM parking brake. This kit also features 365x30mm, 72 vane AP Racing 2-piece floating discs, with each component thoughtfully engineered to resist the heat of prolonged track sessions. The pistons are correctly sized for seamless integration with the OEM master cylinder and ABS system. Whether working in tandem with their front AP Racing by Essex CP9668 or CP9660 Competition Brake Kits, this rear brake kit promises to radically elevate your vehicle’s braking performance.

Radi-CAL

• AP Racing has transformed the brake technology landscape with its revolutionary Radi-CAL asymmetrical brake caliper design. This groundbreaking design incorporates state-of-the-art methodologies such as Computer Aided Design (CAD) and Finite Element Analysis (FEA), pushing the boundaries of conventional caliper design. The Radi-CAL calipers stand at the forefront of brake caliper technology, featuring a distinctive and organic shape that represents a new era of innovation. Since their introduction in 2007, these calipers have consistently surpassed expectations, delivering outstanding performance on professional motorsport race tracks. With a remarkable track record of victories, they have firmly established themselves as a game-changing force in brake performance.
• Benefits of the Radi-CAL Design
  • Significant Stiffness Enhancement – The Radi-CAL calipers demonstrate a remarkable advancement of more than 30% in both static and dynamic stiffness compared to conventional calipers. This substantial stiffness increase effectively minimizes bending when under load, resulting in improved pedal response, precise control, uniform pad wear, and extended caliper lifespan.
  • Substantial Weight Reduction – Despite the significant increase in stiffness, the Radi-CAL design achieves a substantial reduction in caliper weight by eliminating unnecessary mass. This weight reduction contributes to enhanced overall vehicle performance.
  • Optimized Airflow – The Radi-CAL calipers are meticulously engineered to optimize airflow, facilitating efficient air circulation around and through the caliper. This enhanced airflow improves heat dissipation and cooling, thereby elevating the overall performance of the braking system.
  • Efficient Packaging – The Radi-CAL design features an asymmetric caliper profile and internal fluid porting to ensure efficient packaging. This well-thought-out design allows for flexible installation options without compromising performance, enabling optimal integration into various vehicle configurations.

CP9451 PRO5000R Calipers – The Everyman Radi-CAL

• Following eight years of continuous development, multiple iterations, and advancements in manufacturing techniques, the Radi-CAL concept has finally evolved into an affordable solution for racers and enthusiasts at all levels and with various budgets. While numerous products claim to have racing origins, the Pro5000R calipers undeniably possess an authentic lineage. They are direct descendants of the state-of-the-art calipers used in current F1 and Sprint Cup racing. Distinguished by their unconventional appearance, these calipers embody the pure essence of racing design: sleek, minimalist, and exceptionally efficient. While staying true to the previous Radi-CAL design philosophy, they also incorporate remarkable new features that enhance their practicality, convenience, and allure. Essentially, they represent the lightest, stiffest, and most technologically advanced brake calipers ever made accessible to the average enthusiast.
• Traditionally, these intricate calipers were manufactured by machining specialized aluminum alloy billets. The process of removing excess material to achieve the final form proved time-consuming and expensive. Consequently, the price of these calipers remained prohibitively high for the average club racer, time-trialer, or HPDE participant. Fortunately, the Pro5000R calipers employ an innovative drop-forging technique that has significantly reduced manufacturing costs. This breakthrough has made these extraordinary calipers more attainable for a broader range of enthusiasts.

Radi-CAL = Massive Dynamic Stiffness Increase

• Over the years, several approaches have been utilized to reduce the size of brake calipers while maintaining their required stiffness. These strategies have involved robust caliper bridge designs, two-piece calipers with steel through-bolts, the use of advanced 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, more compact, and stiffer. However, the conventional rectangular, boxy shape has remained the prevailing standard for calipers.
• AP Racing has challenged the efficiency of the traditional rectangular box design for brake calipers. They have demonstrated that this design falls short in terms of optimization. When a caliper clamps brake pads against a rotating disc, a significant tangential friction force occurs between the pads and the disc. This force pulls the caliper toward the rotating disc with considerable strength. The caliper resists this force through its rigid mounting points on the spindle.
• During braking, the dynamic load exerted on the caliper causes it to twist or deform, taking on a parallelogram shape. Recognizing the importance of this dynamic force, AP Racing intentionally 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 specifically engineered to accommodate the forces generated during braking.
• The Radi-CAL caliper optimally distributes its body mass along a diagonal axis instead of concentrating it solely at the ends of the caliper. This design enables the caliper mass to better withstand the forces acting on it during braking, rather than relying solely on an empty box structure. By redistributing the mass, the caliper achieves significant weight reduction overall by eliminating non-essential, non-load-bearing material from its 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 takes into account not only what is present but also what is absent. By intentionally redistributing the mass of the caliper, voids are strategically created in unconventional areas. This deliberate mass reduction optimizes the caliper’s size, resulting in an impressively lightweight and compact design. While competing six-piston calipers typically weigh between 9 to 12 lbs, the CP9668 weighs an exceptionally low 6.8 lbs.
• Essex’s approach to brake kit design has always emphasized efficiency, recognizing that excessive size adds unnecessary weight. The Radi-CAL design aligns perfectly with this philosophy. Many brake packages on the market face challenges with wheel fitment, featuring oversized discs and 12-piston calipers that can make it difficult to fit behind OEM wheels or lightweight alternatives. The goal is to save unsprung weight and enable the use of smaller, lighter wheels, which are more accessible and cost-effective when paired with R compound tires. By thoughtfully designing components that prioritize performance, there is no need for excessively heavy calipers. Concerns about stiffness resulting from mass reduction are unfounded since AP Racing’s Pro5000R calipers are not only lightweight but also exceptionally stiff, specifically engineered for racing applications.
• One notable feature of the Pro5000R range is the positioning of the bleed screws and fluid pathways. These 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

• Traditionally, calipers have been manufactured by machining a solid block of exclusive aluminum alloy using a design known as monobloc. In this design, the piston bores and piston seal grooves are machined using a right-angle machine tool that must be inserted into the caliper. The process of removing all the material and achieving the final shape involves labor-intensive and expensive steps, requiring specialized tools and multiple setups. Consequently, monobloc Radi-CAL calipers have been priced beyond the budget of the average club racer, time-trialer, or HPDE participant.
• However, the introduction of a new two-piece drop-forging process has made the Pro5000R caliper a reality. This innovative manufacturing technique allows conventional machine tools direct access to the piston bores, significantly reducing production time and cost while still maintaining an exceptionally rigid structure. With this new process, the Pro5000R caliper offers the same high-performance benefits as the monobloc design but at a more affordable price point.

Hard Anodized Finish

• The primary weakness of typical aftermarket calipers is their finish. Most aftermarket calipers come with a painted finish, such as red, black, or gold. This painted finish is primarily designed for aesthetics and to prevent corrosion in harsh winter conditions. However, when these painted calipers are used on the track, they quickly deteriorate due to chipping, flaking, fading, color shift, and general degradation. Some OEM calipers can even change from their original color to an unsightly shade of brown in as little as one weekend. While some hardcore customers may consider this wear a badge of honor, let’s face it—it still looks unappealing. Moreover, the paint particles end up in undesirable places, which I’ll explain shortly.
• Why does this happen? The culprit is heat. Paint and powder coat finishes are not capable of withstanding the high temperatures experienced on the track. Powder coat, in particular, has issues with shrinkage. When the caliper is heated, the powder coat layer expands and grows, but it doesn’t necessarily shrink back in sync with the caliper body when it cools. This results in a loose and cracked finish hanging on the caliper.
• Paint can also face similar problems depending on the application process. If you were to compare multiple aftermarket calipers from the same manufacturer, you would notice variations in the painted finish. Some calipers may have thicker coats, while others may have thinner coats or slightly different shades. Painting is an art form to some extent and requires a tightly controlled environment. Without such control, variations will always be present. A thick coat of paint can make the caliper look soft around the edges and is prone to cracking off, similar to the issues with powder coat. On the other hand, insufficient paint coverage will result in an uneven appearance and inadequate protection for the underlying aluminum. Furthermore, paint and powder coat can undergo significant color shifts when exposed to heat. Red can turn into maroon or black, gold becomes brown, and black becomes less visually appealing.
• In contrast, the calipers used in Essex Radi-CAL Competition Kits are specifically designed for track use. These calipers are ultra-lightweight, rigid, and durable under all track conditions. They feature a hard anodized finish, which is highly suitable for the demands of the racetrack. When raw aluminum reacts with oxygen, it forms a protective layer called oxidation, similar to rust. The anodizing process capitalizes on this natural phenomenon and takes it a step further by creating a tough layer of aluminum oxide through an electrolytic process. The calipers are immersed in an acid bath and an electrical current is passed through, resulting in an extremely durable and uniform surface. The anodized finish offers superior abrasion resistance compared to paint or powder coat. This means that even if you accidentally hit an anodized caliper with a box wrench while bleeding the brakes, the finish is unlikely to chip off easily. While anodized calipers can still experience some color shift under extreme heat, it requires much higher temperatures to induce noticeable changes, and the shifts are less dramatic. Most importantly, anodized calipers prevent bits of the finish from sticking to the sides of the pistons, ensuring smoother operation and minimizing potential issues.

Ventilated, Domed Back, Stainless Steel Pistons

• The use of aluminum pistons in track calipers has sparked an ongoing debate, with some individuals arguing that the pistons and caliper body should expand at the same rate when heated. However, this argument lacks substantiated evidence and validity. In reality, reputable race caliper manufacturers worldwide exclusively rely on stainless steel or titanium pistons in their high-performance calipers due to their superior performance.
• Stainless steel pistons offer significant advantages, especially in creating a thermal barrier that effectively reduces heat transfer to the brake fluid. This barrier helps prevent a soft pedal caused by fluid fade during intense track use. The superiority of stainless steel pistons has consistently been demonstrated across various levels of motorsport. Despite the higher cost associated with them, the Pro5000R calipers from AP Racing feature meticulously machined stainless steel pistons, setting them apart from many aftermarket calipers that utilize pressed aluminum pistons.
• To further enhance piston stiffness, AP Racing has incorporated a domed shape at the back of the piston. While it may appear to be a minor design element, the introduction of domed back pistons in professional racing has received overwhelmingly positive feedback from drivers. The domed back significantly increases stiffness, resulting in an improved pedal feel that can be distinctly sensed. This design has become the benchmark against which all other designs are measured.
• In addition to the domed back, the pistons in the Pro5000R calipers are equipped with ventilation to enhance heat resistance. The presence of air gaps around the edges of the pistons facilitates additional air circulation, contributing to the cooling process around the pistons. These features collectively slow down and repel the influx of heat into the brake fluid, effectively preventing brake fluid boiling and fade under demanding conditions.

Anti-Knockback Springs

• AP Racing calipers feature stainless steel pistons equipped with anti-knockback (AKB) springs, which may come as a surprise to some. However, these springs serve a crucial purpose in addressing the issue of knockback, which can be unsettling when experienced during braking after a series of S-turns.
• Knockback is commonly observed in fixed calipers and occurs when the wheel, hub, and bearings of a car deflect during cornering, causing the brake disc to move out of synchronization with the caliper and brake pads. This deflection pushes the brake pads apart and retracts the caliper pistons into their bores. However, the piston seals do not have enough tension to fully return the pistons to their original position, resulting in slack within the system. When the brake pedal is applied, it continues to drop until the slack is taken up.
• The inclusion of anti-knockback springs in AP Racing calipers helps alleviate this issue by exerting tension on the backside of the pistons. When the disc deflects and contacts the pistons, the springs push the pistons back into their proper position, reducing the slack in the system. This results in less pedal drop and a more confident braking experience, especially when approaching heavy brake zones.
• It is important to note that the inclusion of lightweight AKB springs does not have significant downsides as long as the caliper is designed to accommodate them. When properly designed and implemented, AKB springs do not cause increased drag or wear on the pads and discs. The shape and material of the piston seals are carefully considered to ensure optimal performance.
• In AP Racing competition calipers, the seals are not simply rings through which the piston slides; they are designed with angles and provide initial friction to limit movement. As the suspension compresses and the disc moves laterally, the seals deform slightly, creating tension or friction that must be overcome before the piston starts moving through the seal ring. The AKB springs add additional resistance and assist in returning the piston to its neutral position.
• When properly designed seals and springs are employed, 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, a bit of friction or tension must be overcome to initiate movement. This arrangement ensures that AP Racing calipers do not cause unnecessary drag or wear on the braking system components.
• Overall, the inclusion of AKB springs in AP Racing calipers addresses the issue of knockback, providing a more reliable and consistent braking experience without compromising performance or causing additional wear on the pads and discs.

High Temperature, Low Drag Seals Without Dust Boots

• Essex often receives an unexpected question from potential customers regarding the maintenance and rebuilding of calipers in their kits, specifically due to the absence of dust boots on the pistons. This question often perplexes them as it lacks intuitive reasoning. In reality, a product that is specifically designed to withstand the extreme high-heat conditions of track use should require less maintenance compared to brake components intended for low-speed and low-temperature street driving.
• To clarify, there is often confusion between piston seals and dust boots. All calipers feature seals, which are small rubber rings inside the piston bores that prevent brake fluid from leaking around the pistons. OEM caliper seals are not engineered to endure constant exposure to high temperatures without becoming brittle and prone to 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-temperature seals are less likely to become brittle and wear out under the demanding conditions of high-heat track use, resulting in significantly reduced replacement and servicing requirements.
• It is important to note that most aftermarket calipers are designed for year-round road use and come equipped with external dust boots. These rubber boots stretch as the pistons extend, aiming to keep contaminants out of the piston bore. While this concept may initially seem appealing, Essex has observed instances where customers have burned through these boots in a single 20-minute track session. Once the boots are burned, the pistons are left with tattered and burnt rubber fragments that provide no benefits. Considering that the boots are quickly destroyed during track use, it becomes unnecessary to include them in the caliper design, eliminating the mess they create.
• Essex’s focus is on providing durable and reliable calipers that can withstand the demanding conditions of track use without sacrificing performance. By utilizing high-temperature seals and omitting dust boots, their calipers require less maintenance, offer enhanced longevity, and deliver consistent performance on the track.

Simple Pad Change with One Bolts

• When the moment arrives to change your brake pads, it’s natural to not anticipate the task eagerly. However, with the Pro5000R calipers, this process becomes a breeze. Bid farewell to the struggle of using hammers, punches, or pliers. AP’s calipers feature bridge bolts that can be effortlessly removed using a 6mm hex wrench. Swapping out pads will now be quicker than ever before. In fact, you’ll spend more time removing the wheel than actually replacing the pads. This means less time tinkering in the paddock and more time savoring the exhilaration of driving.

Lifetime Professional Reconditioning Service

• Essex proudly holds the prestigious honor of being the official AP Racing caliper reconditioning center in North America. Their team consists of highly skilled service technicians who possess specialized expertise in the meticulous rebuilding of a wide range of AP Racing calipers each year. Esteemed calipers from renowned motorsport teams, including those competing in prestigious events such as NASCAR Sprint Cup and ALMS, are entrusted to Essex. This recognition stands as a testament to Essex’s unrivaled proficiency and esteemed reputation within the industry.
  • Caliper Removal and Shipping – To initiate the service process, simply detach your calipers from the vehicle, thoroughly drain and clean them, and send them back to Essex.
  • Hardness Testing – After disassembly, your calipers undergo Rockwell hardness testing, a meticulous assessment that evaluates their fatigue and stiffness levels. This comprehensive test allows us to determine the extent of wear and make informed decisions on whether the calipers should be rebuilt or replaced. Identifying fatigued calipers is crucial in preventing issues such as pad tapering, increased pad wear, seal leakage, and diminished pedal firmness.
  • Ultrasonic Cleaning – Calipers that pass the hardness test undergo a thorough cleaning process using our advanced ultrasonic cleaner. This state-of-the-art cleaning method surpasses traditional hand-cleaning techniques, effectively removing all dirt, debris, and brake fluid for a pristine result.
  • Inspection and Re-Assembly – Every serviceable component of the caliper, including seals, abutment plates, pistons, and bleed screws, undergoes a meticulous inspection. Any components showing signs of wear or damage are replaced to ensure optimal performance and reliability.
  • Cyclical Pressure Testing – Once rebuilt, the calipers undergo rigorous cyclical pressure testing on our specialized bench. This meticulous testing procedure verifies proper functionality and identifies any potential leaks that may occur under specific pressure conditions. By subjecting the calipers to these rigorous tests, we ensure that they meet our stringent quality standards before being returned to you.

Discs – AP Racing Competition J Hook

• The AP Racing J Hook discs featured in this system epitomize the epitome of endurance racing performance. These components of exceptional quality are meticulously engineered to withstand the most challenging conditions you can subject them to. Renowned for their remarkable durability, these discs have a proven track record in professional racing, with multiple victories and championship titles earned in prestigious events such as ALMS, Rolex, and Grand Am. The outstanding performance and established reliability of the AP Racing J Hook discs make them the ideal choice for drivers who prioritize uncompromising performance and long-lasting endurance in their racing pursuits.

Two-Piece Floating Design with Aluminum Hat

• When exposed to heat, iron brake discs, like most metals, undergo significant expansion, leading to an increase in diameter and circumference. This expansion poses a challenge for one-piece disc designs, as they lack provisions to accommodate this expansion. As shown in the image below, when heated, the outer edges of the disc pull away from the center, resulting in distortion and lift, which is known as coning. When the disc is vertically mounted in the caliper, coning directly impacts the contact between the brake pads and the disc, leading to uneven wear, tapering, and an extended brake pedal.
• On the other hand, two-piece discs are specifically engineered to address the expansion caused by heat. This is achieved by incorporating “float” either in the disc itself or in the disc hat/bell. In the example provided, the float is integrated into the disc. If you closely examine the picture, you will observe that the mounting holes for the hat attachment bobbins are oblong rather than circular. These channels allow the hat mounting hardware to slide as the disc heats up and expands. This design ensures that the disc maintains its proper position within the caliper without distortion. By minimizing distortion, stress cracks, and pad taper, this design approach guarantees optimal performance and long-lasting durability of the braking system.

Mounting Hardware and Anti-Knockback Spring Clips

• Upon closer examination of the mounting hardware used in Essex’s Competition Kits, you will discover several often overlooked details that distinguish them from inferior products. These components are not generic bolts sourced from a local retail store; instead, they are custom-made exclusively for Essex and AP Racing in the USA. These high-quality components are the same ones utilized in professional racing applications.
• As previously mentioned regarding piston springs and knockback, effectively managing the lateral movement of the disc is crucial during track driving. To address this, we incorporate anti-knockback spring clips at every other disc attachment point. For instance, a ten-bolt disc assembly would include five spring clips, while a twelve-bolt disc would have six. These spring clips play a vital role in maintaining alignment between the disc hat and the iron ring, while also allowing for radial expansion and floatation of the disc. Moreover, they provide the added benefit of preventing any rattling or noise originating from the disc hat and iron disc assembly.

Hat Design

• In addition to their other notable advantages, floating two-piece discs provide an additional benefit of reducing heat conduction to the hubs and bearings. This reduction in heat transfer plays a significant role in minimizing wear and tear on these crucial components, resulting in an extended lifespan. The disc hats, an integral part of the assembly, are meticulously crafted from 6061 heat-treated billet aluminum, ensuring exceptional strength even in high-temperature conditions. To further optimize 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. It is worth noting that the hats feature scallops on the underside, which promote efficient heat dissipation along the outer face of the disc once they are installed.

Internal Vane Quantity and Quality

• The design of AP Racing J Hook discs distinguishes them from OEM-style discs and other aftermarket brands, especially in terms of their internal vane design. 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, which can cause turbulence as air passes through. This design prioritizes disc face stability and cost efficiency rather than efficient heat evacuation. Another vane design seen in certain OEM discs is the straight, non-directional internal vane, which offers better airflow than pillar vanes but still falls short of the directional vanes featured in AP Racing discs.
• AP Racing discs utilize directional vanes that are optimized to spin in a specific direction, maximizing the airflow 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 meticulously engineered to promote smooth airflow and enhance cooling performance.
• Furthermore, AP Racing discs surpass many aftermarket discs in terms of 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 decreased 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.
• A close examination of the internal vane design clearly reveals the unique features of AP Racing J Hook discs. These discs have 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 enhances the airflow performance.
• It is essential to emphasize that the majority of cooling air entering a brake disc originates from the backside of the discs, particularly when brake ducts are utilized. 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 provides a clear and unobstructed path for cooling air to enter and flow through the disc, while the OEM discs feature narrower inlet ports and potential obstructions that hinder the flow. Consequently, the AP Racing disc maintains significantly lower temperatures, reducing the likelihood of cracking and wear.

Exclusive AP Racing J Hook Slot Pattern

• When modifications such as slots or holes are introduced to a brake disc, they can impact heat transfer in various ways. These modifications may create cool spots around the slots or holes as the disc heats up, which is not ideal. Ideally, heat should be evenly distributed across the disc to facilitate effective cooling through airflow and radiation. The presence of cool spots can lead to areas of stress concentration and increase the likelihood of disc cracking. Moreover, cool spots can cause uneven distortion of the disc’s face, resulting in uneven pad deposits, vibrations, and judder.
• Original Equipment Manufacturer (OEM) discs address this issue by leaving the disc face blank, thus avoiding the formation of cool spots. While this approach reduces the risk of noise, vibration, and harshness (NVH), it also results in a decrease in pad bite and the tactile feedback experienced through the brake pedal. On the other hand, many aftermarket discs on the market feature straight slots, which tend to create cool spots across the disc face between the slots.
• Through extensive research and development, AP Racing has developed the J Hook design to provide a solution to these challenges. The J Hook design creates a consistent pathway of evenly distorted material on the disc face. The hooks are strategically spaced around the disc’s circumference and from the inside edge (where the hat attaches) to the outer edge, with a slight overlap. This design promotes even heat distribution and distortion across the disc, thereby reducing the risk of cracking. Additionally, the uniform heating of the disc facilitates 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 remarkable legacy spanning over fifty years in brake component design, AP Racing has an illustrious track record that speaks for itself. Their components have played a pivotal role in the triumph of cars that have claimed victory in over 750 Formula 1 races, a testament to their expertise and unwavering reliability. In fact, when you survey the NASCAR Sprint Cup grid during any race weekend, you will discover that 75% or more of the cars feature AP J Hook discs.
• Drawing upon this wealth of experience, AP Racing has developed their own exclusive iron alloy, renowned for its exceptional durability. Every aspect of this alloy is meticulously crafted to withstand the harsh conditions it will encounter. Unlike OEM discs that prioritize cost-effectiveness and ease of production, AP Racing’s disc design objectives are set apart. They maintain an unyielding focus on delivering unparalleled performance and unwavering reliability, ensuring that their products can endure the most demanding usage without any compromise.

Caliper Brackets & Hardware

• The caliper brackets provided in this kit are meticulously crafted with utmost precision 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 adhere to the same high standards employed in professional racing, utilizing aircraft-grade hardware that meets stringent quality requirements.
• One notable advantage of our brackets lies in their thoughtfully designed cutaway feature. This unique design allows for seamless compatibility with various brake duct kits available in the market. The cutaway design ensures a precise and secure fit, enabling efficient cooling and optimal airflow to the brakes—a crucial element for achieving peak performance on the track.

Brake Ducting

• Essex, drawing on their extensive experience, advises against the use of aftermarket brake ducts in conjunction with their Competition Brake Kits. Their experience has revealed challenges in achieving effective airflow from the front of the car to the center of the brake discs due to packaging limitations. The narrow diameter of the duct hoses and restricted space within the fender well make it difficult to properly install adequately sized hoses that can provide sufficient cooling. Moreover, many aftermarket systems direct cooling air to incorrect locations, resulting in uneven cooling and temperature variations across the disc surface. These temperature differentials can contribute to premature cracking.
• Furthermore, the plates used to attach brake ducts at the wheel hub can inadvertently trap heat against the inner disc face, leading to increased system temperatures. Considering these factors, Essex does not recommend the use of aftermarket brake ducts.
• If your vehicle is equipped with OEM brake ducts that channel air into the wheel well or has 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 possible solutions.
• It is crucial not to attach 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 placed in between.

Spiegler Stainless Steel Brake Lines

• The Competition Kits are supplied with stainless steel brake lines renowned for their exceptional craftsmanship. Spiegler lines set themselves apart from other options in the market, providing a comprehensive array of features that deliver unparalleled performance advantages.

Disc Burnishing / Bedding Service

• Ensuring proper preparation of your brake discs before taking them on the track is crucial to avoid potential issues such as juddering, vibration, and cracking. However, conducting these preparations at the circuit can be challenging, time-consuming, and may pose risks to other drivers. Moreover, on-track preparations can be inconsistent due to factors like changing weather conditions and traffic, making it difficult to achieve the desired level of repeatability for optimal bedding and consistent performance.
• To address these concerns, Essex now offers a professional burnishing service to all customers, extending this service beyond their racing clientele. This service allows individuals to have select Competition Brake Kits pre-burnished at Essex’s facility. Leveraging their extensive experience in 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 maximum efficiency from AP Racing disc brake sets.
• It is important to note that the pads included in your kit will not be pre-burnished. In other words, the burnishing procedure for the discs does not have to be performed with the exact set of pads that come with your kit. Essex will perform the burnishing process on the discs using the pad compound of your choice, ensuring that you can enjoy the benefits of the procedure while using the provided pads from your kit.

Features

• Weighs roughly the same as the OEM Sport Package setup, despite AP discs being significantly larger (15mm larger in diameter and 10mm thicker)
• Retains OEM parking brake functionality
• Features AP Racing CP9451 Radi-CAL four piston calipers
• 365x30mm, 72 vane AP Racing 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 our front AP Racing by Essex CP9668 and CP9660 Competition Brake Kits.

What’s In The Box

• One pair AP Racing CP9451 Radi-CAL Pro5000R racing calipers.
• One pair 365x30mm AP Racing 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.
  • Choosing the optimal racing brake pads is a matter of personal preference. Unlike other manufacturers who include low-quality pads in their brake kits, Essex takes a different approach. They have removed the cost of pads from their system, allowing customers to have complete control over their pad selection. When you purchase the kit, you have the freedom to choose a set of front pads that align with your specific preferences and requirements. Essex provides this opportunity at a significant discount compared to the retail price, ensuring that you can customize your brake setup without incurring unnecessary expenses. This places you in full control, empowering you to precisely tailor your braking system according to your preferences.
  • DS1.11 – Widely recognized for its exceptional performance in endurance racing, the DS1.11 brake pad remains a popular choice among racers. Positioned within the moderate range of endurance racing compounds, it offers a lower friction coefficient (mu) compared to the 3-12 pad. As temperatures rise, the DS1.11 exhibits decreasing torque, providing enhanced control when using street tires. Although its interaction with discs is less aggressive, resulting in a potentially shorter lifespan, it still demonstrates remarkable resistance to high temperatures. The DS1.11 is highly regarded for its ability to deliver excellent fade resistance in the demanding conditions of endurance racing.
  • DS2500 – When it comes to track performance, dedicated race pads often deliver outstanding results. However, the DS2500 brake pad stands out as an impressive hybrid option suitable for both street and track use. It provides a moderate bite, offers good resistance to fading, and generates manageable levels of dusting and noise compared to other street pads. In certain cases, there may be some squealing with specific vehicles when used in its intended role. If your needs include high-speed driving, canyon runs, or occasional light track use with road tires, the DS2500 is highly recommended.
  • DS3.12 – Introduced in 2019, the DS3.12 is the latest addition to Ferodo’s esteemed DS line of brake pads. Designed from the ground up to meet the demanding requirements of modern sports cars with increased power and aerodynamics, it sets new standards in performance. The DS3.12 offers exceptional performance for heavier vehicles that utilize stickier tires. Extensive testing has demonstrated its ability to maintain a remarkably consistent torque curve across a wider range of temperatures compared to other pad compounds from various manufacturers. This ensures consistent braking even in high-temperature conditions, reducing wear rates without excessive damage to the discs. Additionally, the DS3.12 exhibits higher friction coefficient (mu) properties, requiring less pedal pressure for consistent unfaded performance in hotter temperatures. With its revolutionary design, the DS3.12 is positioned to become the benchmark pad after undergoing rigorous testing.
  • DSUNO – If you appreciate the effectiveness of the DS1.11 brake pads but seek increased stopping power, the DSUNO pads are worth considering. While these pads may have a 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 possess a significant advantage: they are engineered to accommodate brake pads from various manufacturers. Each manufacturer has its own unique pad dimensions, resulting in slight variations in fit. This means that pads from different manufacturers or different batches may fit the calipers with varying degrees of tightness or play, which can potentially lead to noise generation. To address this issue, Essex has developed the Essex Designed Pad Tension Kit. This specialized kit is designed to reduce pad movement within the caliper, minimizing associated noise and providing a quieter braking experience. It is important to note that each caliper requires one Pad Tension Kit, and a complete set of calipers would require two kits.

Applications

• 2009-2021 Nissan 370Z – Z34
  • Application Type – Track
• 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.