AP Racing Radi-CAL Competition Rear Kit 340mm - S550 Mustang

The AP Racing by Essex Radi-CAL Competition Brake Kit is a rear brake upgrade for the 2015-2023 S550 Mustang, including Mach 1. It pairs AP Racing CP9450 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 12 lb of unsprung weight from the rear of the car compared with the OEM brakes. Each caliper weighs 5.8 lb without pads, against 8.4 lb for the factory caliper. Each two-piece disc weighs 12.0 lb, compared with 17.0 lb (Mach 1) for the original 330mm disc. The caliper takes a 16.7mm thick pad for long life and heat tolerance. 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 S550 Mustang, the CP9450 caliper mounts radially on a dedicated bracket at 152mm centers with a 44.1mm offset, with an M10x1.0 inlet thread. 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. The disc metallurgy is designed for the temperatures seen on track, for a long service life. Spiegler stainless steel brake lines with a clear sheath reduce compliance compared with the OEM rubber lines. The caliper uses a commonly available pad shape.

Features

• AP Racing CP9450 four-piston calipers
• 340 x 28mm, 48-vane J Hook discs on floating hats
• About 12 lb less unsprung weight
• 16.7mm thick brake pads
• Pistons sized for the OEM master cylinder and ABS

What's Included

• One pair AP Racing CP9450 Radi-CAL Pro5000R racing calipers
• 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 Enkei 20 inch. Check your wheel with the Essex wheel fitment template before ordering.

Fitment