N15 Design 355mm Radi-CAL Brake Kit w/ AP Racing CP9660 Caliper – E46 M3




Based on the AP Racing CP9660 Pro5000R Radi-CAL caliper, the N15 Design 355mm brake kit for the E46 M3 was designed for the harsh environment of track and race use. We spent months developing and testing the kit on a high downforce, high grip, and high horsepower car to ensure each component of the kit performs flawlessly and is appropriate for the application.


The CP9660 caliper was designed with motorsports in mind. The design goal was to achieve maximum stiffness with the lightest weight possible. Material in non-crucial parts of the caliper was removed to keep the weight down.


An 18mm pad is standard for this caliper and is available in a commonly available pad shape. Nearly all pad manufacturers have their compounds in this shape, so you will never have problems finding a pad to compliment your existing rear setup.


Pad knock-back is all but eliminated with this caliper, even when the pads are run down to near the backing plate due to the anti-knock back springs installed behind each piston. In our testing, we have also found that it is no longer necessary to set the pads on the straight before entering a braking zone. We have also found that rotor hat anti-rattle clips/springs included in many other kits are not necessary to prevent knock back.


The AP Racing J-Hook rotors provide excellent consistency and wear characteristics due to their advanced metallurgy even when running an aggressive brake compound. The fully floating aluminum hat/rotor combination allow the rotor ring to expand and contract freely, reducing the potential for rotor cracking due to heat cycling. Replacement parts for the kit are readily available from us or AP Racing, so you will never have to worry about where you will find parts.


In our testing, we found that the 355mm (14″) rotor size is the appropriate size for the power and weight of the average E46 M3 track/race car. Smaller rotors result in rapid brake pad and rotor degradation. Larger rotors resulted in over cooling and increased rotor degradation.


We also focused on making sure the mounting hardware is suitable for the application. The N15 Design caliper adapter bracket is CNC machined from 6061 aluminum and aligns the caliper perfectly on the upright. Many manufacturers use bolts instead of studs on their brackets which can result in stripped threads during a rushed rotor swap. We went the extra mile and spec’d motorsport grade studs and metric jet nuts (for clearance purposes on the caliper), so you never have to worry about finding the right socket or stripping your brackets. All of our hardware is bolt on, and no modifications to the knuckle are required.


Included in the kit:

  • (2) AP Racing CP9660 Calipers, Left and Right
  • (2) AP Racing 355x32mm J-Hook Rotors, Left and Right, Fully Assembled to Hat
  • (2) N15 Design Caliper Adapter Brackets, hardware pre-installed
  • (2) Front brake lines
  • (2) AP Racing Caliper Temperature Stickers
  • Various Mounting Hardware





Additional information

Weight 55 lbs
Dimensions 20 × 20 × 20 in