AP Racing by Essex Radi-CAL Comp Brake Kit - Rear CP9451 (15-21 WRX/STI)

Advantages Over OEM Brake System

Our CP94X/340mm Radi-CAL Competition Brake Kit offers our customers the following advantages over the OEM brake system:

AP Racing Radi-CAL calipers are the stiffest, lightest, and most technologically advanced calipers available at any price

Calipers use a commonly available brake pad shape

Ventilated, domed back, stainless steel pistons keep heat out of the brake fluid and provide an ultra-firm pedal

Mitigation of pad knockback via anti-knockback springs behind the caliper pistons

Anodized caliper finish that is resistant to wear and deterioration at elevated temperatures

Stainless steel caliper hardware for a long caliper service life under frequent pad change conditions

High temperature, low drag seals that will hold up to track temps= less rebuilding and longer service life

No dust boots to burn up

Simple pad change with one bolt, no caliper removal required

Lifetime professional caliper rebuilding support by Essex (at a fee)- pull off your calipers, send them to us, we clean, inspect, and rebuild them

Available disc burnishing service ensures that your kit arrives ready to be installed and driven hard immediately

Championship winning, 60 vane, fully floating, AP Racing J Hook racing discs

Anti-knockback/anti-rattle disc attachment hardware

Replacement iron disc rings available at an extremely competitive replacement price ($329 each).

Disc metallurgy specifically designed to handle the temps typically seen on track offer a long service life

Highest quality, Spiegler stainless steel brake line with clear sheath that reduces compliance over OEM rubber design

“Radi-CAL” is a blanket term used to describe AP Racing’s patented asymmetrical brake caliper design. Radi-Cal technology is grounded in Computer Aided Design (CAD) and Finite Element Analysis (FEA), and allows for organic, alien-looking designs that are a radical departure from conventional caliper designs of the past. Radi-CAL's are widely considered the pinnacle of current brake caliper technology. Since their inception in 2007, these revolutionary calipers have amassed a lengthy string of race victories at all levels of professional motorsport, while redefining brake performance expectations. For more details on the design concept and what these calipers have achieved in professional racing.

The key benefits of the Radi-CAL design:

Massive Stiffness Increase- A 30+ % increase in both static and dynamic stiffness vs. conventional calipers allows for far less deflection under load, which means superior pedal feel & modulation, more even pad wear, and longer caliper service life.

Considerable Mass Reduction- Removing all extraneous caliper mass lowers the caliper weight, despite the huge stiffness increases.

Optimized Airflow- Air moves around and through the caliper more efficiently, providing superior heat evacuation and cooling.

Efficient Packaging- The asymmetric caliper profile and internal fluid porting allows the caliper to fit into tighter spaces.

WHAT'S IN THE BOX?

One pair AP Racing CP94X Radi-CAL Pro5000R racing calipers

One pair 340x28mm AP Racing CP8972, 60 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 our 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 our system with a set of pads you probably don't want anyway, we've decided to remove the cost from our system and allow our customers to choose the pads that best suit their needs/wants. When purchasing our kit, you are able to choose one set of front pads at a substantial discount vs. the retail price. Please use the drop-down menu to select your pads.

Pad Tension Clips (frequently referred to as anti-rattle clips) are NOT included with our Competition Kits, but we do offer them as an option if you're concerned about NVH. One of the great benefits of the AP Racing calipers in our 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.

Vehicle Fitment

• 2015 - 2021 Subaru STI
• 2015 - 2021 Subaru WRX

WARNING: Operating, servicing and maintaining a passenger vehicle or off-road vehicle can expose you to chemicals including engine exhaust, carbon monoxide, phthalates, and lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. To minimize exposure, avoid breathing exhaust, do not idle the engine except as necessary, service your vehicle in a well-ventilated area and wear gloves or wash your hands frequently when servicing your vehicle. For more information go to https://www.P65Warnings.ca.gov/passenger-vehicle.