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The factory C8 brakes can stop a Corvette. That's not the problem.
The problem begins when you add slicks, aero, speed, heat, and repeated high-energy braking events and then ask the system to deliver the same pedal, the same modulation, and the same confidence every single lap.
The AP Racing by Essex CP9668 Competition Brake Kit is built specifically for that job: six-piston Radi-CAL racing calipers, enormous 25mm-thick race pads, fully floating 372x34mm 72-vane AP Racing J-Hook discs, stainless pistons, anti-knockback technology, racing seals, and approximately 12 fewer pounds hanging from the nose than the factory Z51 brake package.
A driver can adapt to almost any reasonable brake torque. What destroys confidence is a pedal, bite point, or response that changes as the session progresses.
Caliper stiffness, stainless pistons, racing seals, and rigid lines reduce the variables between your foot and the brake pads.
Highly ventilated racing discs and 25mm-thick pads are designed to absorb and reject enormous amounts of energy repeatedly.
A stiff caliper gives the driver a clearer relationship between pedal pressure and braking torque instead of hiding it behind component flex.
Pads, discs, seals, pistons, and other wear components are designed around the reality that race brakes eventually need service.
We ran AP Racing brake systems exclusively on our C5 race car for seven years. During that time, we never once gave serious thought to whether the braking system was capable of doing what we were asking from it.
We're now asking the same thing from a roughly 3700-pound C8 running slick tires and substantial aero. Still no drama.
That's really the highest compliment we can give a brake system. When you're hurtling toward a braking zone, you have plenty of things to think about already. Whether the pedal is going to be where you left it should not be one of them.
Traditional brake calipers tend to look like boxes because that's a convenient shape to manufacture.
AP Racing's Radi-CAL architecture instead puts material where the caliper actually needs it during a braking event. The asymmetric shape is designed around the dynamic loads trying to twist and distort the caliper while the pads clamp a rotating disc.
The result is an architecture with more than a 30% increase in static and dynamic stiffness compared with conventional caliper designs while simultaneously removing unnecessary mass.
That's how you end up with a six-piston competition caliper weighing only about 6.9 pounds without pads.
Less caliper deflection means less pedal travel wasted bending the caliper, better modulation, and more consistent pad contact across the disc.
The CP9668 weighs approximately 6.9 lb without pads, versus roughly 11.1 lb for the factory Z51 front caliper.
No external crossover tubes means fewer vulnerable parts hanging off the caliper and more efficient packaging around the wheel.
Open space around the pistons and fluid pathways allows cooling air to move through the caliper instead of trapping heat inside a giant block of aluminum.
AP uses machined stainless-steel pistons rather than aluminum. Stainless steel transfers heat far less readily, helping create a thermal barrier between the screaming-hot brake pad and the hydraulic fluid behind it.
The pistons are ventilated and use a domed-back architecture for additional stiffness.
Behind them sit anti-knockback springs. During hard cornering, hub and disc movement can push the pads and pistons backward into the caliper. The next time you hit the brake pedal, you first have to take up that unwanted clearance.
The springs help keep the pistons where they belong, reducing the dreaded surprise long pedal when you arrive at the next braking zone.
Virtually every major detail in the Pro5000R exists because brake temperature on track is dramatically different from anything encountered during normal road use.
Motorsport-style high-temperature piston seals are designed to survive repeated high-heat operation without becoming brittle.
Bellows-style dust boots can burn and deteriorate at racing temperatures. Pro5000R calipers simply eliminate them.
Electroless Nickel Plating provides a durable, easy-to-clean surface that handles the heat and abuse of competition use.
AP offers closely related Radi-CAL calipers that use the same basic pad footprint but different pad thicknesses. The reason to choose the CP9668 is very simple: you want more consumable material.
Plenty of pad for typical 20–40 minute HPDE sessions, time trials, and sprint racing. It is lighter and narrower, giving you more wheel-spoke clearance.
The better choice for multi-hour endurance use, very heavy pad consumption, or anyone who simply wants to change pads substantially less often. The tradeoff is roughly another pound including pads and about 14mm less wheel-spoke clearance.
AP designed the Pro5000R around frequent race-car maintenance.
The standard bridge bolts come out with a simple 6mm hex wrench without removing the caliper from the car.
The CP9668 also includes a quick-change spring-clip bridge. Squeeze it, lift it, pull the pads out. In many cases you'll spend more time removing the wheel than actually changing the brake pads.
The caliper gets most of the attention, but the disc is where the kinetic energy of the car actually becomes heat. Consequently, a huge amount of the engineering in this system lives in the rotor assembly.
The iron ring can grow radially as temperature increases without forcing the aluminum hat to follow that expansion, reducing coning, distortion, stress, and uneven pad contact.
Left- and right-specific curved internal vanes actively pump cooling air through the disc instead of relying on a simple non-directional internal structure.
AP's J-Hook slot pattern provides pad-face cleaning and bite while promoting more uniform thermal behavior across the disc face.
Heat-treated aluminum hats reduce unnecessary rotating mass while reducing heat conduction into the hubs and wheel bearings.
That sounds obvious, but accommodating thermal expansion is one of the fundamental differences between a serious racing rotor and a conventional one-piece road-car disc.
When a constrained iron disc heats and expands, it can distort into a cone. Once that happens, the pads are no longer meeting a flat disc. Pad taper, judder, inconsistent pedal travel, and cracking can follow.
AP's fully floating architecture allows the iron ring to expand relative to the hat while continuing to run true in the caliper. This is not a styling feature. It's how a racing disc survives repeated thermal cycles.
A common approach to building a "big brake kit" is simply to make everything enormous.
Essex takes the opposite approach: use enough brake to survive the job, then remove mass anywhere it isn't contributing to performance.
~12 lb lighterThe complete CP9668/372 front system removes approximately 12 pounds of unsprung mass from the nose compared with the factory C8 Z51 brake package.
Essex selects piston sizing specifically around the C8 so the front kit works with the factory hydraulic and electronic systems rather than treating the Corvette as a generic chassis with a brake bracket attached to it.
Caliper piston area is selected to work with the factory master cylinder rather than requiring a wholesale hydraulic-system redesign.
Piston sizing and brake torque are chosen to closely mimic the original axle relationship so the factory ABS system can remain.
The front CP9668 package can be installed with the OEM rear braking system or paired with the corresponding AP Racing by Essex rear kit.
Diameter is only half of brake-to-wheel fitment. The CP9668 is a wide six-piston caliper, and spoke shape and offset determine whether a wheel clears the outside face of the caliper.
Essex has confirmed several factory Z06 and Forgeline wheel applications without spacers, but wheel fitment should always be verified for your specific wheel before ordering.
Important: the OEM C8 19-inch Trident front wheel does NOT clear the CP9668 without a wheel spacer.
Download Wheel Fitment TemplateThe Pro5000R architecture prioritizes track performance, heat tolerance, low mass, rapid servicing, and pedal consistency.
That means features you might expect from an OEM street caliper—most notably external rubber dust boots—are intentionally absent. Competition pads can also make noise, and depending on pad dimensions and whether a tension kit is installed, some pad rattle may be present.
If your priority is silence, road salt, winter corrosion protection, and never thinking about brake maintenance, you're looking at the wrong category of brake system.
If your priority is repeated braking at race-track temperature, you're in exactly the right place.
We actually prefer it that way.
Brake compound selection depends enormously on tire, vehicle weight, track, driver, session length, temperature, and personal preference. Stuffing a generic set of pads in an expensive race brake kit simply so the box can say "pads included" doesn't do anyone a favor.
The CP9668 uses a widely available motorsport pad shape, allowing you to choose the compound that makes sense for your car rather than paying for a set you were going to throw on the shelf anyway.
We stock G-LOC pads specifically for the CP9668 / CP9669 family in the proper 54mm radial depth and 25mm thickness, supplied without the eyelet that otherwise needs to be ground off before installation.
Pad-tension / anti-rattle hardware is optional rather than included. This allows the caliper to accept pads from many manufacturers while giving customers who care about paddock and street NVH an additional noise-control option.
Shop G-LOC Pads For CP9668 / CP9669Read the complete Essex C8 front-brake installation procedure before taking the car apart. One particularly important C8-specific step: disconnect the battery before opening the hydraulic system.
View Installation Guide →Print the template at 100% scale and physically check your wheel. Wheel diameter alone does not guarantee spoke clearance around a CP9668 caliper.
Download Fitment Template →These kits are expensive. So are tires, entry fees, engines, bodywork, and mistakes caused by arriving at a braking zone without complete confidence in the pedal. AP Racing Competition systems are built so the brakes become one less variable between you and a fast lap.
