AP Racing Radi-CAL Competition Rear Kit 340mm - Subaru WRX VB

The AP Racing by Essex Radi-CAL Competition Brake Kit is a rear brake upgrade for the 2022-2025 Subaru WRX (VB). It pairs AP Racing CP9451 Radi-CAL Pro5000R racing calipers with 340 x 28mm, 48-vane AP Racing J Hook discs on fully floating aluminum hats, built for track days and competition driving.

Why upgrade

The kit removes about 5 lb of unsprung weight from the rear of the car compared with the OEM brakes. Each caliper weighs 4.85 lb without pads, against 6.3 lb for the factory 1-piston Sliding Caliper. Each two-piece disc weighs 11.1 lb, compared with 13.2 lb for the original 290mm disc. The caliper takes a 16.75mm thick pad for long life and heat tolerance. The OEM parking brake keeps working. Every component is designed to resist the heat of extended track sessions. Pistons are sized to work seamlessly with the OEM master cylinder and ABS.

Caliper and disc construction

On the Subaru WRX VB, the CP9451 caliper mounts radially on a dedicated bracket at 152mm centers with a 44mm offset, with an M10x1.0 inlet thread. Anti-knockback springs behind the caliper pistons limit pad knockback. The anodized caliper finish resists wear and deterioration at high temperatures. Stainless steel caliper hardware gives a long service life even with frequent pad changes. There are no dust boots to burn up at track temperatures. Pads change with one bolt, with no caliper removal. The championship-winning 48-vane AP Racing J Hook discs are fully floating. The discs use anti-knockback, anti-rattle attachment hardware.

Features

• AP Racing CP9451 four-piston calipers
• 340 x 28mm, 48-vane J Hook discs on floating hats
• About 5 lb less unsprung weight
• 16.75mm thick brake pads
• Pistons sized for the OEM master cylinder and ABS

What's Included

• One pair AP Racing CP9451 Radi-CAL Pro5000R racing calipers in Anodized Finish
• One pair 340x28mm AP Racing CP6565 heavy duty 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.

Specifications

Video

Fitment notes

This rear kit fits the vehicles in the table below, which we confirmed against two sources using US model years. Essex has confirmed clearance with Rays Gram Lights 57 18x9.5 inch ET38. Check your wheel with the Essex wheel fitment template before ordering.

Fitment