GiroDiscs Front Brake Rotor Kit Slotted for 964 with 993TT Caliper Upgrade

Item Number: GIR-A1-046

Detailed Description

Compatible Models: 964 with 993TT Caliper Upgrade

The GiroDisc system is a direct replacement for the OE disc on select model Porsche's with factory iron rotors. No modifications are necessary. The disc will bolt directly to the car and work with OE calipers perfectly. By upgrading your brakes with lightweight high performance replacements as opposed to a big brake kit, your factory bias is maintained as well as your ABS efficiency. The GiroDisc front rotors are approx 21.0 lbs vs. 25.6 lbs for the stock units. This reduction in rotational and unsprung weight allows for quicker acceleration and suspension response.

The central hat section of this rotor is made from strictly U.S. sourced 6061-T6 aircraft specification aluminum. The disc is made from a proprietary cast iron, poured in the USA and machined from start to finish in house at GiroDisc. The rotor utilizes a curved vane design, developed in racing to act as a centrifugal pump to force cooling air through the disc.

The rotor and hat have a floating mount system, which utilizes 8 or 10 high strength alloy steel drive pins, manufactured by GiroDisc in the USA and cadmium plated for a long lasting corrosion resistance. These pins take the load from braking actions while maintaining the axial and radial float between the hat and disc. The pins are secured by grade 12 cap screws with hardened washers. In order to keep the rotors from making noise when cold, the pins are mounted with anti-noise spring washers on the rotor side which allow the rotor to grow with heat expansion but eliminate the rattle and noise associated with floating rotors. This float also allows the rotor to self center between the pads.

Once the GiroDisc system is in place, simply replace the cast iron rotor when needed.

Important Notes

During checkout, please include your car's specific year/make/model in the notes section to ensure the kit is shipped with the correct hats and hardware.
Product listing is for upgrade kit, slotted only. Please contact us for drilled/slotted applications.
Rotors are sold/priced per pair.

About GiroDisc

GiroDisc is a brake technology company that is dedicated to the development and manufacturing of high quality brake components and brake systems. GiroDisc products are designed and engineered for both street and track applications with a comprehensive product line of two-piece floating rotors that are designed to be a direct replacement for the factory rotors. The two-piece floating rotor will improve braking performance, reduce unsprung weight and utilizes the factory calipers and e-brake.

Unlike many “big brake” packages on the market, GiroDisc rotors also retain the factory brake bias and outstanding pedal feel. High quality construction and premium grade materials provide improved wear, increased rotor life, minimized coning and greater cooling efficiency. GiroDisc rotors come slotted and are also available with an optional drilled pattern.

The relentless pursuit of enhanced performance has earned GiroDisc multiple victories in Porsche endurance racing. GiroDisc combines valuable lessons learned at the track with the latest technologies to develop the highest performance brake systems for Porsche.

GiroDisc Slotted Rotors

Frequently Asked Questions

Q: What is required to install the Girodisc system?
A: The Girodisc system is a direct replacement for the OE disc.
No modifications are necessary. The disc will bolt directly to the car and work with OE calipers and pads perfectly. Once the Girodisc system is in place, simply replace the cast iron rotor when needed. Some discs are larger in diameter and come with caliper spacers. If longer bolts are required, they are also supplied.

Q: How does reducing weight of the braking system benefit the vehicle?
A: The Girodisc will generally weigh between 4 – 8 lbs less than the oe disc it will replace. This is due to the heavy cast iron hat section being replaced with lightweight, high strength aluminum. The mass of any vehicle requires energy to accelerate or decelerate. Reducing the vehicle mass improves acceleration, and requires less energy to be dissipated during deceleration. Rotating mass requires additional energy in order to increase or decrease its speed of rotation. Decreasing the mass of the disc has a great benefit due to reduction in rotational inertia. This will allow more of the braking force to be available to decelerate the vehicle, not the disc.
Additionally, the mass of the brake system is also unsprung mass. Reducing the unsprung mass has the additional benefit of improved suspension performance, resulting in enhanced ride and handling. Rotating masses require additional energy to vary the plane on which they turn. The lighter the disc, the quicker the response of the vehicle steering due to the reduction in gyroscopic effect/rotational inertia of the disc. As an example, compare the weight of the Ferrari 360 OE disc at 18.2 lbs, and the Girodisc at 14 lbs. The Girodisc is 4.2 lbs lighter per disc. Replacing all four discs will save 16.8 lbs of rotating, unsprung mass.

Q: Why slotted discs?
A: The edges of the slots continuously clean and refresh the pad surface. This will allow the pads to have a maximized friction surface always available. Additionally, they prevent containments from collecting between the pad and disc interface.
The disc is lightened, decreasing its rotational inertia.
Slots prevent the formation of a water film on the disc in wet weather, maintaining the best brake response.

A note on drilled discs:
Girodisc does not recommend drilled discs for high performance track applications. The rapid heating and cooling cycles will cause cracking on the friction surface of a drilled disc. The use of high friction or racing pads will exaggerate this condition. Most pad manufacturers specifically recommend that their race pads not be used on a drilled disc for this reason. Girodisc can drill discs for an additional fee, if the customer is aware of the potential hazards of drilling the discs.

Girodisc brake kits are available in drilled/slotted configurations for high performance street use, please contact us for more information.