Custom J Hook Pattern OEM Replacement Disc (Rear 345x24mm- Left Hand)- Toyota GR Supra 3.0 Premium
Part #: 20.05.10023
Custom J Hook Pattern OEM Replacement Disc (Rear 345x24mm- Left Hand / Driver Side) for the Toyota GR Supra 3.0 Premium:
- OEM brake disc that has been custom-machined with the proven J Hook slot pattern
- Improved bite, resistance to cracking, and consistent heat distribution across the disc face
- Promotes an even transfer layer of material for bedding in brake pads
- Matches the slot pattern of our AP Racing by Essex Competition Radi-CAL 9660, Radi-CAL 9668, and World Radi-CAL II Road Brake Kits
***Directional and sold individually - matching Right Hand Disc
J Hook Slot Pattern
When you cut a slot or drill a hole in a disc you impact heat transfer. The area around the slot or hole acts as a cool spot when the disc heats up, which is not ideal. Ideally, heat is distributed uniformly around the disc so it can be hit with the cooling air that is pumping through the disc, radiate outwards away from the disc, etc. Cool spots create stress risers and increase the likelihood of the disc cracking. They also cause the face of the disc to distort unevenly, leading to uneven pad deposits, vibration, and judder.
The OEM discs avoid this
problem by simply leaving the face blank. While the risk for NVH goes
down slightly, so does the pad bite and feel of the disc through the brake
pedal. Competitive aftermarket offerings typically have straight slots,
which tend to leave cool spots across the disc face between the slots.
During exhaustive R&D testing, AP's J Hook design was found to create a constant pathway of evenly distorted material on the face of the disc. The hooks are spaced out as evenly as possible both around the circumference of the disc, as well as from the inside edge (where the hat attaches) to outer edge, with a slight overlap to promote even heat distribution/distortion. In addition to reducing cracking, the even heating of the disc also helps provide an even transfer layer of pad material on the disc when you bed them in.
Additionally, the J Hook slot pattern produces a greater number of leading edges for the pads to bite into vs. a traditional curved slot pattern, and particularly a plain-faced disc. The benefits include more even heat distribution, less propensity to crack, cleaner pad material transfer during bed-in, and more bite.