AP Racing Radi-CAL Front Kit 372mm - S550 Mustang

The AP Racing by Essex Radi-CAL Competition Brake Kit is a front brake upgrade for the 2015-2023 S550 Mustang, including Mach 1. It pairs AP Racing CP9668 Radi-CAL Pro5000R six-piston calipers with 372 x 34mm, 72-vane AP Racing J Hook discs on fully floating aluminum hats, built for track days and competition driving. Clears OEM 19 inch wheels without spacer and fits inside many popular 18 inch track wheels.

Why upgrade

The kit removes about 30 lb of unsprung weight from the front of the car compared with the OEM brakes. Each caliper weighs 6.9 lb without pads, against 10.2 lb for the factory caliper. Each two-piece disc weighs 20.1 lb, compared with 34.4 lb for the original 380mm disc. The 25mm pad is thicker than the 15.8mm factory pad, so it lasts longer and absorbs more heat between changes. 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. It works with the OEM rear brakes or a matching AP Racing rear kit.

Caliper and disc construction

On the S550 Mustang, the CP9668 caliper mounts radially on a dedicated bracket at 180mm centers with a 42mm 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 two bolts or a quick-change spring clip, with no caliper removal. The championship-winning 72-vane AP Racing J Hook discs are fully floating. The discs use anti-knockback, anti-rattle attachment hardware.

Features

• AP Racing CP9668 six-piston calipers
• 372 x 34mm, 72-vane J Hook discs on floating hats
• About 30 lb less unsprung weight
• 25mm thick brake pads
• Pistons sized for the OEM master cylinder and ABS

What's Included

• One pair AP Racing CP9668 Radi-CAL Pro5000R six piston calipers
• 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.

Specifications

Video

Fitment notes

This front kit fits the vehicles in the table below, which we confirmed against two sources using US model years. Check your wheel with the Essex wheel fitment template before ordering.

Fitment