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AP Racing ⨉ Essex CP9668 Radi-CAL ENP Competition Front Brake Kit for RZ34 Nissan Z



Radi-CAL ENP Competition Front Brake Kit

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AP Racing ⨉ Essex CP9668 Radi-CAL ENP Competition Front Brake Kit for RZ34 Nissan Z

Unleash the full braking potential of your Nissan Z with the AP Racing ⨉ Essex Radi-CAL ENP Competition Front Brake Kit. This performance-enhancing kit integrates AP Racing’s cutting-edge Radi-CAL calipers, a revolutionary design that boasts superior stiffness, reduced weight, and improved cooling, delivering a dramatic boost to braking power and consistency, even under the most intense track conditions. The system includes a proprietary ENP (Electro Nickel Plated) treatment on the calipers to provide enhanced resistance to corrosion, coupled with high-performance J Hook discs for an unparalleled pedal feel and heat management capabilities. With its bolt-on installation, rigorous track testing, and the proven pedigree of AP Racing and Essex, this brake kit is a high-performance, durable solution, tailored to elevate the braking performance of the Nissan Z to racing standards.


  • AP Racing revolutionizes brake technology with its patented Radi-CAL asymmetrical brake caliper design. This groundbreaking advancement thrives on cutting-edge technologies such as Computer Aided Design (CAD) and Finite Element Analysis (FEA). Unlike traditional designs of the past, this contemporary technology allows for the creation of distinctively unconventional calipers with an organic form that pushes the boundaries of innovation. Widely regarded as the pinnacle of brake caliper technology, Radi-CAL calipers have continuously set new standards since their introduction in 2007. Their exceptional performance has been proven on race tracks across various levels of professional motorsport, earning numerous victories and solidifying their reputation as a game-changer in brake performance.
  • Benefits of the Radi-CAL Design
    • Significant Stiffness Enhancement – The Radi-CAL calipers showcase an impressive increase of over 30% in both static and dynamic stiffness compared to conventional calipers. This remarkable stiffness improvement minimizes deflection under load, resulting in superior pedal feel and modulation, even pad wear, and prolonged caliper service life.
    • Substantial Weight Reduction – By eliminating unnecessary caliper mass, the Radi-CAL design successfully reduces the overall weight of the caliper, despite the substantial increase in stiffness.
    • Optimized Airflow – The Radi-CAL calipers are engineered to optimize airflow, allowing air to circulate around and through the caliper more efficiently. This efficient airflow enables superior heat evacuation and cooling, enhancing overall brake performance.
    • Efficient Packaging – With its asymmetric caliper profile and internal fluid porting, the Radi-CAL caliper is designed to fit into tighter spaces efficiently. This thoughtful design allows for more flexible installation options without compromising performance.

CP9668 PRO5000R Calipers – The Everyman Radi-CAL

  • After years of continuous evolution and refinement, the highly anticipated Radi-CAL Pro5000R brake caliper is now available, offering high-performance capabilities for racers of all experience levels. Inspired by F1 and Sprint Cup technology, the design philosophy behind these calipers goes beyond the ordinary, combining lightweight construction with both functionality and aesthetic appeal. Advancements in manufacturing techniques have made them more accessible and convenient without compromising their peak performance capabilities. In essence, these calipers represent some of the most technologically advanced brake systems on the market, making them an ideal choice for any enthusiast eager to hit the track.
  • Traditionally, these intricate calipers were crafted from expensive proprietary aluminum alloy billets, making them prohibitively expensive for average club racers, time-trialers, or HPDE participants. However, the Pro5000R calipers utilize a new drop forging operation that has significantly reduced production expenses and, consequently, the entry cost. This breakthrough in manufacturing has made this remarkable technology accessible to a wider audience, allowing more people to experience its benefits and performance advantages.

Radi-CAL = Massive Dynamic Stiffness Increase

  • Throughout the years, various strategies have been employed to reduce the size of brake calipers while maintaining adequate stiffness. These strategies include robust caliper bridge designs, two-piece calipers with steel through-bolts, the use of exotic materials like Beryllium and MMC, forging instead of casting, and the adoption of monobloc designs. All of these innovations aimed to make calipers lighter, smaller, and stiffer. However, the traditional rectangular, boxy shape remained the accepted standard for calipers.
  • AP Racing has challenged the notion that a rectangular box is the most efficient shape for a brake caliper. They have proven that the conventional design is not optimal. 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 hard mounting points on the spindle.
  • The dynamic load placed on the caliper during braking events causes it to twist or pull into a parallelogram shape. AP Racing recognized the importance of this dynamic force and designed the Radi-CAL caliper specifically to address it. Unlike traditional calipers that were designed in relative isolation from the forces they were meant to combat, the Radi-CAL caliper was intentionally designed around the forces of a braking event.
  • The Radi-CAL caliper optimally distributes its body mass on a diagonal rather than concentrating it at the ends of the caliper. This design allows the caliper mass to support the forces acting on it during braking, as opposed to relying solely on an empty box structure. The redistribution of mass also enables a significant reduction in overall weight by removing non-essential, non-load-bearing material from the caliper body.

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

  • As previously mentioned, the Radi-CAL design philosophy focuses not only on what is present but also on what is absent. The design intentionally relocates caliper mass, creating voids in non-traditional locations. This strategic removal of mass from the caliper body optimizes its overall envelope, 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.
  • The Essex approach to brake kit design has always been centered around efficiency, understanding that anything larger than necessary adds unnecessary weight. The Radi-CAL perfectly aligns with this philosophy. Many brake packages on the market suffer from the issue of wheel fitment. They feature oversized discs and 12-piston calipers that can pose challenges when trying to fit them behind OEM wheels or lightweight alternatives. The goal is to save unsprung weight and allow for the use of smaller, lighter wheels that are more readily available and cost-effective when paired with R compound tires. Properly designed components that prioritize performance negate the need for excessively heavy calipers. Concerns about stiffness due to mass reduction are unfounded. AP Racing’s Pro5000R calipers are not only lightweight but also incredibly stiff, purpose-built for racing applications.
  • One notable feature of the Pro5000R range is the placement of the bleed screws and fluid pathways. The calipers incorporate internal fluid porting, with only two bleed screws positioned 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 need to be attended to during brake fluid replacement. The elimination 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 facilitates increased airflow between and around the pistons and brake fluid pathways. This improved airflow enhances overall system operating temperatures, contributing to better performance and durability.

Two-Piece, Drop-Forged Caliper Body

  • Calipers have traditionally been machined from a single, solid block of proprietary aluminum alloy, known as a monobloc design. With this design, the piston bores and piston seal grooves can only be machined using a right-angle machine tool, which needs to be inserted into the caliper. Machining away all the material with specialized tools and multiple setups to achieve the final shape is a time-consuming and expensive process. Consequently, monobloc Radi-CAL calipers have been priced out of reach for the average club racer, time-trialer, or HPDE participant. However, the development of a new two-piece drop-forging process has made the Pro5000R caliper a reality. This innovative manufacturing technique allows conventional machine tools to access the piston bores directly, resulting in a significant reduction in production time and cost while still maintaining an exceptionally rigid structure.

ENP (Electroless Nickel Plated) Finish

  • One notable weakness of typical aftermarket calipers is their finish. Most aftermarket calipers come with a painted finish, whether it’s red, black, or gold. This painted finish aims to provide an attractive appearance and prevent corrosion in harsh winter conditions. However, when these painted calipers are exposed to track environments, there are associated issues such as chipping, flaking, fading, color shifting, and overall degradation of the finish in a relatively short period of time. Some OEM calipers can even change color from the original shade to an unattractive brown in just one weekend. While some may consider this wear as a badge of honor, the reality is that it doesn’t look appealing. Additionally, the paint particles can end up in undesirable places, as we’ll discuss shortly.
  • Why does this occur? The culprit is heat. Paint and powder coat finishes are not well-suited to handle the high temperatures experienced on the track. Powder coat finishes, in particular, are prone to shrinkage issues. The powder coat layer expands and grows when the caliper is heated, but it doesn’t necessarily shrink in tandem with the caliper body when it cools down. As a result, the loose shell of finish cracks and deteriorates.
  • Paint can also face similar issues depending on its application. If you were to compare several aftermarket calipers from the same manufacturer, you would likely notice slight variations in the painted finish. Some calipers may have thicker coats, while others have thinner ones, leading to slightly different shades of color. Painting requires a precise and controlled environment, and without it, variations in application are bound to occur. A thick coat can make the part appear soft and is prone to cracking, similar to the powder coat issues mentioned earlier. On the other hand, insufficient paint coverage leads to an uneven appearance and inadequate protection for the underlying aluminum. Furthermore, both paint and powder coat finishes undergo significant color shifting when exposed to heat. Red can turn into maroon or black, gold can become brown, and black simply becomes less appealing.

Ventilated, Domed Back, Stainless Steel Pistons

  • Some individuals argue that aluminum pistons are ideal for track calipers, claiming that the expansion rates of the pistons and caliper body should be the same when heated. However, this argument lacks validity and proof. In reality, all reputable race caliper manufacturers worldwide exclusively use stainless steel or titanium pistons in their high-performance calipers. This choice is based on the fact that stainless steel pistons offer superior performance.
  • Stainless steel pistons excel at creating a thermal barrier, effectively minimizing heat transfer to the brake fluid and preventing a soft pedal caused by fluid fade on the track. This superiority has been repeatedly demonstrated across various levels of motorsport. While most aftermarket calipers utilize pressed aluminum pistons, the Pro5000R calipers employ expensive machined stainless steel pistons.
  • To enhance piston stiffness, AP Racing has designed the back of the piston with a domed shape. Although it may seem like a small design element, the introduction of domed back pistons in professional racing received immediate and overwhelmingly positive feedback from drivers. The domed back significantly increases stiffness, which can be felt through the pedal. Consequently, this design has become the benchmark against which all other designs are measured.
  • For enhanced heat resistance, the pistons are equipped with ventilation. Air gaps around the edges of the piston facilitate 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

  • The pistons used in AP Racing calipers are not only made of stainless steel, but they also incorporate anti-knockback (AKB) springs. You might be surprised to find springs in pistons, but they serve a crucial purpose. If you’ve ever experienced your pedal dropping after a series of S turns when entering a brake zone, you’ve encountered knockback. This phenomenon can be quite unsettling. Professional drivers often lightly tap their brakes before a brake zone to combat knockback.
  • Knockback commonly occurs with fixed calipers. It happens when the wheel, hub, and bearings of your car deflect during cornering, causing the brake disc to move out of synchronization with the caliper and brake pads. The degree of knockback varies depending on the vehicle and the amount of deflection observed in the aforementioned components. As the brake disc deflects, it pushes the brake pads apart, pushing the caliper pistons back into their bores. However, the piston seals lack sufficient tension to fully return the pistons to their original position, resulting in slack within the system. When you apply the brake pedal, it continues to drop until the slack is taken up.
  • Anti-knockback springs help alleviate this situation by exerting tension on the backside of the pistons. When the disc deflects and comes into contact with the pistons, the springs push the pistons back into their proper position, reducing the slack in the system. Consequently, there is less pedal drop and fewer nerve-wracking moments when approaching heavy brake zones.
  • There are no significant downsides to lightweight AKB springs 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 taken into consideration.
  • During driving, the suspension compresses, the disc moves laterally, and the pads are slightly pushed away from the disc. It’s 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 an AP Racing competition caliper, the groove where the seal resides isn’t a square cut groove; it has angles. As the pistons slide in or out, there is friction between the outer piston wall and the seal, causing the seal to deform slightly, as illustrated below.
  • A certain amount of tension or friction must be overcome before the piston starts moving through the seal ring. This tension/friction prevents the piston from dragging on the disc once the pistons are pushed back into the bores due to disc/suspension movement.
  • With the addition of AKB springs, slightly more force is 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, a bit of 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, or Quick-Change Spring Clip (CP9668 only)

  • 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.
  • The convenience of the CP9668 caliper goes even further with its inclusion of two bridge options as standard. You can opt for the fixed bridge or utilize the quick-change spring clip that is provided. Opening the spring clip is as simple as squeezing and lifting. This innovative feature makes changing pads faster and easier than ever before.

Pistons Sized Specifically for Your Car

  • The piston sizes in the brake systems are carefully selected to closely match the OEM brake torque on a specific axle. This means that front systems can be easily installed on stock cars without any adverse effects or negative impact on the ABS system. There’s no need to replace the stock master cylinder or the OEM rear brake system.

Lifetime Professional Reconditioning Service

  • Essex serves as the official caliper reconditioning center for AP Racing in North America. Their team of skilled service technicians specializes in rebuilding hundreds of AP Racing calipers each year for top teams in motorsport, such as NASCAR Sprint Cup and ALMS.
  • Removal and Shipping – Simply remove your calipers from the car, drain and clean them, and ship them back to Essex.
  • Hardness Testing – Upon disassembly, your calipers undergo Rockwell hardness testing to assess their fatigue and stiffness loss. This test helps us determine the extent of wear and recommend whether the calipers should be replaced or rebuilt. Tired calipers can lead to issues like pad tapering, increased pad wear, leaky seals, and loss of pedal firmness.
  • Ultrasonic Cleaning – Calipers that pass the hardness test undergo thorough cleaning in Essex’s state-of-the-art ultrasonic cleaner. This process removes all dirt, debris, and brake fluid, delivering results that surpass hand-cleaning methods.
  • Inspection and Re-Assembly – All serviceable parts of the caliper, including seals, abutment plates, pistons, and bleed screws, are inspected and replaced as necessary to ensure optimal performance.
  • Cyclical Pressure Testing – After the calipers are rebuilt, they undergo rigorous cyclical pressure testing on a specialized bench. This testing ensures proper functioning and identifies any leaks that may only manifest under specific pressure conditions.

Discs – AP Racing Competition J Hook

  • The AP Racing J Hook discs featured in this system are the ultimate choice for endurance racing. These high-performance components are built to withstand the most demanding conditions you can subject them to. Renowned for their durability, these discs have a proven track record in professional racing, having secured 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 companion for drivers seeking top-notch performance and longevity 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. This expansion poses a challenge for one-piece disc designs. 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 for accommodating this expansion. As a result, the edges of the disc distort and lift, 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 long brake pedal.
  • In contrast, two-piece discs are specifically engineered to compensate for disc expansion when heated. This compensation is achieved by incorporating “float” into either the disc itself or the disc hat/bell. In the case of the image below, the float is integrated into the disc. If you closely examine the picture, you’ll notice that the mounting holes for the hat attachment bobbins are not circular but oblong in shape. These channels enable the hat mounting hardware to slide as the disc heats up and expands, allowing the disc to maintain its true position within the caliper without distortion. This design approach minimizes distortion, stress cracks, and pad taper, ensuring optimal performance and longevity of the braking system.

Mounting Hardware and Anti-Knockback Spring Clips

  • Upon close inspection of the mounting hardware utilized in Essex’s Competition Kits, you’ll discover several often overlooked details that set them apart from inferior products. These components are purposefully designed and not just generic bolts sourced from a local retail store. They are custom-made in the USA exclusively for Essex and AP Racing, the same components employed in professional racing applications.
  • As previously mentioned in relation to 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 employ anti-knockback spring clips at every alternate disc attachment point. For instance, a ten-bolt disc assembly would incorporate five spring clips, while a twelve-bolt disc would feature six. These spring clips serve to maintain the alignment between the disc hat and the iron ring, while still permitting radial expansion and floatation of the disc. Furthermore, they provide the added benefit of preventing any rattling or noise from the disc hat and iron disc assembly.

Hat Design

  • In addition to their other advantages, floating two-piece discs offer the added benefit of minimizing heat conduction to the hubs and bearings. This reduction in heat transfer helps mitigate wear and tear on these valuable components, ultimately contributing to their longevity. 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 are treated with a hard anodized coating. 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, allowing heat to dissipate effectively 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 pillar vane designs found in many OEM discs, AP Racing discs employ a different approach. Pillar vanes consist of interconnected posts or pillars that join the two halves of the disc, creating turbulence as air flows through them. This design is primarily focused on disc face stability and cost efficiency, rather than efficient heat evacuation. Another type of vane design seen in some 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 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 swapped from side to side. 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 facilitates 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, the 60+ vane discs offered by AP Racing demonstrate enhanced resistance to coning, distortion, and cracking. They also deliver benefits such as reduced brake fade, minimized judder, more consistent pad contact, and extended service life.
  • In comparing the internal vane design, one can observe the distinct features of the AP Racing J Hook disc. Notably, the AP Racing disc exhibits 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’s important to note that most cooling air entering a brake disc originates from the back side of the discs, especially 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 offers a clear and unobstructed path for cooling air to enter and flow through the disc, whereas the OEM discs feature narrower inlet ports and potential obstructions hindering 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 made on 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. Ideally, heat should be distributed uniformly across the disc so that it can be effectively cooled by the airflow and radiate away from the disc. 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, leading to uneven pad deposits, vibration, and judder.
  • OEM discs address this issue by leaving the disc face blank, avoiding the formation of cool spots. While this reduces the risk of noise, vibration, and harshness (NVH), it also results in a decrease in pad bite and the tactile feel of the disc through the brake pedal. On the other hand, many competitive aftermarket discs feature straight slots, which tend to leave cool spots across the disc face between the slots.
  • Extensive research and development testing conducted by AP Racing led to the development of the J Hook design, which creates a consistent pathway of evenly distorted material on the disc face. The hooks are strategically spaced out around the disc’s circumference and from the inside edge (where the hat attaches) to the outer edge, with a slight overlap to promote 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 over 50 years of experience in designing brake components, AP Racing has a remarkable track record. Their components have been used on cars that have won more than 750 Formula 1 races, showcasing their expertise and reliability. In fact, during any given race weekend, you can find AP J Hook discs on 75% or more of the NASCAR Sprint Cup grid.
  • Drawing from these extensive experiences, AP Racing has developed a proprietary iron alloy that exhibits exceptional durability. This alloy is specifically designed to withstand the demanding conditions that you intend to subject it to. Unlike OEM discs, which prioritize cost-effectiveness and ease of production, the design objectives for AP Racing’s discs are vastly different. Their focus is on delivering high performance and reliability, ensuring that their products can withstand rigorous use without compromise.

Caliper Brackets & Hardware

  • The caliper brackets included in this kit are precision-machined from heat-treated 6061 T6 billet aluminum, renowned for its strength and durability. To further enhance their resilience, the brackets undergo a hard anodizing process. The same high standards is maintained as those used in professional racing, using aircraft-grade hardware that meets stringent quality requirements.
  • A notable advantage of their brackets is their thoughtfully designed cutaway feature. This design allows for precise fitting of various brake duct kits currently available in the market. The cutaway design ensures a snug and secure fitment, enabling efficient cooling and airflow to the brakes, an essential aspect for optimal performance on the track.

Brake Ducting

  • Essex does not recommend the use of aftermarket brake ducts in conjunction with their Competition Brake Kits. Based on 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 hinder the installation of properly-sized hoses that can provide adequate 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 an overall increase in system temperatures. Considering these factors, we do 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 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, we encourage you to reach out to us to discuss possible solutions.
  • It is crucial not to bolt 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, with no objects sandwiched in between.

Spiegler Stainless Steel Brake Lines

  • These Competition Kits come equipped with top-of-the-line stainless steel brake lines, renowned for their exceptional quality. Spiegler lines stand out from competing options due to their extensive range of features, which provide unparalleled performance advantages.

Disc Burnishing / Bedding Service

  • If proper preparation is neglected before taking your brake discs out on the track, you may encounter issues such as juddering, vibration, and cracking. However, conducting the necessary preparations at the circuit can be challenging, as it consumes valuable practice time and can pose hazards to other drivers in close proximity. Additionally, on-track preparations lack consistency due to external factors like changing weather conditions or traffic, which can hinder the repeatability required for optimal bedding and constant stopping and restarting.
  • To address these concerns, Essex now offers a professional burnishing service available to all customers. Initially reserved for 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 maximum efficiency from AP Racing disc brake sets.
  • It’s important to note that the pads you receive 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 burnish the discs in the pad compound of your choice, ensuring the benefits of the procedure while using the pads provided in your kit.


  • Saves 25+ unsprung lbs. from nose of the car vs. OEM brakes, despite being considerably larger.
  • Features AP Racing CP9668 Radi-CAL Pro5000R six piston calipers.
  • Jewel-like ENP caliper finish is incredibly durable and easy to clean.
  • 372x34mm, 72 vane AP Racing disc.
  • Uses 25mm (1 inch) thick brake pads.
  • 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 AP Racing By Essex Rear Brake Kit.

What’s In The Box

  • One pair AP Racing CP9668 Radi-CAL Pro5000R six piston calipers in ENP Finish (Electroless Nickel Plated).
  • One pair 372x34mm 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.
    • Racing brake pads are a highly personal choice – Many manufacturers include a set of inexpensive, low quality pads with their brake kits – Rather than artificially inflating the price of the system with a set of pads you probably don’t want anyway, they’ve decided to remove the cost from their system and allow customers to choose the pads that best suit their needs / wants – When purchasing this kit, you are able to choose one set of front pads at a substantial discount vs. the retail price.
    • DS1.11 – The DS1.11 has a lower mu than the 3-12 and is known as a moderate brake pad for endurance racing compounds; it requires more pressure on its pedal but provides drivers with declining torque when temperatures rise. A few find that this offers better control over street tires, although it doesn’t last quite so long due to less aggression against discs. It still boasts impressive max temperature resistance though not up par with the 3-12’s, being mainly recognized based upon sensation -with fade resistance serving well in this circumstance too.
    • DS2500 – When it comes to the track, you always get better performance from a dedicated race pad. That being said, the DS2500 is an excellent hybrid street / track pad on offer which has moderate bite and good resistance against fading; as well as manageable dusting and noise levels compared to other street pads. Some vehicles may emit some squeal when this pad’s used in its designated role – however if your needs include high-speed driving / canyon runs or occasional light track use (with road tires), then there isn’t anything that beats the DS2500.
    • DS3.12 – The latest iteration in Ferodo’s impressive DS line, the DS3.12 released in 2019, was designed from ground up to handle all of the high demands placed on a vehicle by modern sports cars: increased horsepower and aerodynamics meant heavier curb weights that require stickier tires. Testing has revealed that out of any pad compounds available from many manufacturers, only the DS3.12 offers an impressively flat torque curve across a wider range of temperatures than ever before – meaning each time you hit your brakes around turns or tracks it will always feel consistent no matter how hot they get for reduced wear rates without damaging discs too much compared to other Ferodo pads. It also features higher mu properties requiring less pressure applied onto pedals when braking frequently so performance remains unfaded despite hotter temps; making this revolutionary new compound not just better than related products but likely be seen as soon as gold standard after testing is completed.
    • DSUNO – If you are a customer who appreciates the effectiveness of the DS1.11 brake pads yet would like increased stopping power, check out the DSUNO pads. While this compound does not provide as much longevity in comparison to the DS1.11 product, its peak friction coefficient (mu) is greater once optimal operating temperature has been reached on-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.
    • One of the great benefits of the AP Racing calipers in this system is that they are designed to accommodate pads from a wide range of manufacturers – Each manufacturer builds their pads with specifications that are slightly different – As such, pads from different manufacturers, or even from different batches, won’t always fit in the calipers in exactly the same manner – Some pads are a snug fit, while others may rattle around and produce noise – The Essex Designed Pad Tension Kit is designed to dramatically reduce pad movement inside the caliper, along with just about all resulting noise – Please note that each caliper requires one Pad Tension Kit (2 per).


  • 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.

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.
Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.
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