AP Racing by Essex 2-piece J Hook Discs for the 992 GT3 OEM Calipers!01.13.2022
Written by Jeff Ritter
We are excited to announce that our front replacement discs in the OEM 408mm iron size for the 992 GT3 are now available for purchase! The rears are identical to the 991 GT3 and are available here. We also do plan on producing front and rear replacements for the OEM PCCB disc as well, but we aren't quite there yet.
Even more exciting is that we are introducing a new internal vane technology in our front 2-piece discs for the 992 GT3. It is called the Sinusoidal Vane, which AP sometimes refers to internally as the 'Wave' Vane for obvious reasons as you’ll see below. This tech is something that has helped AP Racing brake systems win championships in international GT racing, as well as multiple NASCAR Cup championships here in North America. As one of the most desirable track weapons on the planet, we wanted the 992 GT3 to be the first production car application for this technology in North America. Just as AP Racing's Radi-CAL calipers set a new benchmark for caliper stability, cooling, and durability, the Sinusoidal Vanes have done the same for iron racing discs.
The concept for this disc design originated in NASCAR Cup. Up until the debut of the Next Gen car (for which AP/Essex are supplying the spec brake package), we were cramming our brake systems inside tiny 15” wheels. Trying to squeeze adequate brake thermal mass into a wheel that small is incredibly challenging, particularly when you have a 1,000 HP and 3,000 pounds mashing on them every few seconds from 200 mph…for hours on end! In a wheel that small, there isn’t anywhere for the heat to go, and the durability of every component is crucial. We were constantly looking for ways to provide the Cup teams with increased durability, stability, and cooling, and that’s what led AP to this technology.
Benefits of the Wave Vane disc technology vs. traditional curved vanes:
- Increased thermal stability- Wild temperature swings are what causes discs to crack. When you stand on the brakes for an approaching corner, your disc temperatures skyrocket and the iron expands. As you travel down the subsequent straight, the discs are blasted with cooling air. The longer the straight and the higher the speed, the greater the temperature drop, and the further the iron contracts. This expansion and contraction cycle places a huge amount of stress on the iron and is what causes them to eventually crack. That’s why tracks with relatively slow corners at the end of high-speed straights, followed by another long straight, decimate brake discs (think Watkins Glen or Road America). In an ideal world, once you brought your discs up to race temps, you would keep them at a constant temperature for the entire session. The Sinusoidal Vane brings the discs closer to that goal by decreasing the difference between the maximum and minimum disc temperature by as much as 35%. That means a less dramatic temperature swing and greater crack resistance and durability.
- Reduced maximum disc temperatures by 10%+: Not only are temperature swings less intense with the Wave Vane, the maximum temperatures reached are substantially lower. For example, in one NASCAR test the Wave Vane discs showed a peak temp of 1328F and a minimum temp of 1085F (delta of 243F), while the traditional curved vanes maxed out at 1490F and a min of 1121F (delta of 369F). Not only was the difference between min and max more subdued, the max temperature reached by the Wave Vane disc was 162F lower!
- Increased cooling surface area- Each of the internal Wave Vanes has a larger cooling surface area vs. a traditional curved vane.
- Greater support for the disc face- A disc’s internal vane structure provides the support lattice behind the disc face. Having many internal vanes impacts airspeed and heat transfer through the disc, reduces air recirculation between vanes, and reduces deflection at the disc face. In practical terms, a disc with a high number of vanes is more thermally stable, maintains more even contact with the brake pads (which reduces uneven pad deposits/judder), and is less prone to distortion. In summary, the Wave Vane design provides even greater support for the disc face than AP’s standard curved vane designs.
- Reduced weight- The Wave Vane design provides a slight unsprung weight reduction vs. a similar disc with curved internal vanes.
While we're on the NASCAR topic...Below is our front brake package for the Next Gen NASCAR Cup car which will be hitting a track near you very soon! Every car will have this setup. What's great about these is that they will finally sit inside an 18" wheel. That means the brakes won't be woefully undersized as they have been in the past, and the drivers are certainly loving them!