AP Racing Radi-CAL Competition Front Kit 372mm - Porsche 997, 991, 981

The AP Racing by Essex Radi-CAL Competition Brake Kit is a front brake upgrade for the Porsche 997 and 991 911 and the 981 Boxster and Cayman. It pairs AP Racing CP9661 Radi-CAL Pro5000R racing calipers with 372 x 34mm, 72-vane AP Racing J Hook discs on fully floating aluminum hats, built for track days and competition driving.

Why upgrade

The kit removes about 3-4 lb of unsprung weight from the front of the car compared with the OEM 991 Base/T brakes despite huge size increase (330mm --> 372mm). Each caliper weighs 6.2 lb without pads, against 9.5 lb for the factory caliper. Each two-piece disc weighs 21.0 lb (with hat), compared with 22.1 lb for the original 330mm disc. The caliper takes a 18mm thick pad for long life and heat tolerance. The caliper takes pads from all major pad manufacturers. 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 Porsche 997, 991, 981, the CP9661 caliper mounts radially on a dedicated bracket at 180mm centers with a 42mm offset, with an M10x1.0 inlet thread. 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. 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 18mm thick pad shape. Ventilated, domed-back stainless steel pistons keep heat out of the brake fluid for a very firm pedal.

Features

• AP Racing CP9661 six-piston calipers
• 372 x 34mm, 72-vane J Hook discs on floating hats
• About 3-4 lb less unsprung weight
• 18mm thick brake pads
• Pistons sized for the OEM master cylinder and ABS

What's Included

• One pair AP Racing CP9661 Radi-CAL Pro5000R racing calipers
• One pair 372x34mm AP Racing CP7177, 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. Essex has confirmed clearance with APEX SM-10 18x8.5 inch, APEX SM-10 18x9 inch ET46, OEM Porsche Carrera T ( inchS4 inch) Wheels 20x8.5 inch ET49 and Volk Racing TE37 Ultra 19x8.5 ET52. Call us about the Porsche 718 Boxster, Porsche 718 Boxster GTS, Porsche 718 Boxster GTS 4.0, Porsche 718 Boxster S, Porsche 718 Boxster T and Porsche 718 Cayman before ordering; we have not confirmed fitment for them yet. Check your wheel with the Essex wheel fitment template before ordering.

Fitment