RENNKIT™ Cal*Cool™ / Girodisc 2-Piece Rotors

Cal*Cool™ Caliper Cooler Kit for 996 Turbo or Carrera 4S with Larger 350 mm Rotors (not PCCB)

A popular upgrade to the C4S and Turbo are larger diameter rotors – swapping out stock 330 mm rotors to larger 350 mm rotors like the 997 Turbo.  This change provides better braking action and feel.

The only problem is brake calipers over-heat and cook the brake fluid during track use.

Rennkit™ has the solution:  Cal*Cool™ caliper coolers.  A simple modification that allows excessive heat to dissipate to Rennkit’s unique caliper coolers, where conductive and convective heat transfer dissipates excess caliper heat when driving. While parked, conductive and radiative heat transfer continue to effectively remove heat from the calipers.  Track tested – all 4 corners remained below 370F!

Cal*Cool™ caliper coolers are simply inserted between caliper and wheel hub carrier using provided longer and stronger bolts.  Far more surface area than the simple skinny aluminum collars others sell – reduces vibration and fatigue.  All hardware is included, along with easy to follow step by step illustrated instructions backed by the customer service that Rennkit™ is known for.  Come with 2 year limited warranty.
(NOT FOR CARS WITH STOCK 330 mm ROTORS or PCCB Ceramic brakes)

Kit contents: 

  • Cal*Cool™ Caliper Coolers for 350 mm Front Brake rotors
  • High Strength Black Oxide (150,000 psi) Socket Bolts
  • High Temp Heat Transfer Paste
  • Detailed Illustrated Step by Step Instructions (emailed with order):

996 Model :

996 Model :

996 Model :

Cal*Cooler Kit + Girodiscs – ALL 4 CORNERS
Set of 4 Girodisc 350mm 2-Piece Rotors  PLUS Cal*Cooler Kit for all 4 Corners – Save $$$ over purchasing separately!

Upgrades all 4 corners – uses existing pads, or more aggressive track pads.

996 Model :


Girodisc 2-Piece Rotors

For 996 / 997 / 991 Series Porsches®


Why upgrade to Girodisc rotors on your high-performance Porsche 911?

  • Replaces current heavy 1-piece iron rotors with the lighter weight Girodisc 2-piece unit (Aluminum/Iron)
  • Reduces unsprung weight at each corner – more responsive suspension
  • For 996 Turbo and C4S; easily upgrade to larger diameter 350 mm rotors for better stopping force
  • Replace expensive PCCB ceramic rotors with less costly 2-piece aluminum/iron rotors, especially on the track.

The central hat is 6061-T6 aluminum.  The disc is a proprietary cast iron and machined start to finish by Girodisc.  Rotors utilizes a curved vane design, developed in racing to act as a centrifugal fan, forcing cooling air through the disc.


Drilled holes are not used as they tend to crack under heavy use such as at the track. The rotor and hat have a floating mount system, utilizing 8 or 10 high strength alloy steel drive pins, manufactured to Girodisc specifications, with cadmium plating for long lasting corrosion protection. The pins take the load from braking actions while maintaining axial and radial float between hat and disc. The pins are secured with grade 12 cap screws and hardened washers. To keep the rotors from making noise when cold, the pins are mounted with anti-noise spring washers. This allows the rotor to grow with heat expansion, but eliminates rattle and noise associated with floating rotors. This float allows the rotor to self center between the pads.


Bonus:  Once the Girodisc rotors are in place, simply replace the cast iron disc once worn below suggested limits.

We have the rebuild kit as well; iron rings with all hardware and instructions to replace the iron rotors.  Or we can have them done for you.  $350 front or rear.


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