The Girodisc system is a direct replacement for the OE disc however you
must use the same pad shape that is used on the 991 GT3 that came with
the iron rotors from the factory.  The annulus (pad swept height) of
these pads is smaller than the large PCCB pads, this is done to keep the
rotor weight at a reasonable
level and allow far better pad selection.  If we manufactured a rotor
with the same annulus as the OEM PCCB rotors they would be unnecessarily
heavy.

The central hat section of our rotor is
made from strictly U.S. sourced 6061-T6 aircraft specification
aluminum.  The disc is
made from our own 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 to
our own specifications 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.