Cost Savings: The initial cost of 2-piece rotors are more expensive, everyone knows that. However, two piece brake rotors last considerably longer than any 1-piece grey iron rotor. Real life experience on the track, where enthusiasts are only able to get two or maybe three track days on standard rotors, we are now able to get one or possibly two complete seasons running Girodisc's 2-piece version. With normal daily/street driving, we've had customers clock up to 60,000 miles before needing a new replacement ring. The beauty of a 2 piece rotor design is, when it comes time to replace or service your rotors, you only need to replace the rotor ring instead of the entire assembly.
Curved Vanes: Many Girodisc two piece rotors are directional and utilized curved vanes. What's that? Upon inspection of almost any automotive brake rotor you should notice between the two rotor faces there are a bunch of small columns, these are the "vanes". As your car moves and the rotor spins, air washes through these columns and helps to cool the rotor by removing built up heat. Most OEM or factory replacement rotors utilize Pillar vanes. This type of vane can only cool the rotor with air that gets into the wheel well and passes through it. Girodisc curved vane rotors as mentioned above are directional, so there are left and right casting both with unique curved vane designs. These vanes are designed by Girodisc to create negative pressure inside the rotor as it spins by forcing air out using centrifugal force. The faster you go, the faster the rotor spins, thus more and more air is forced through our two-piece rotor's curved vanes aiding in up to a 40% improvement in cooling.
"Unsprung" Weight Reduction: Girodisc 2-piece rotors, along with most any two-piece rotors help to increase agility and overall handling by significantly reducing unsprung weight from your vehicle. Generally speaking, the more unsprung weight (weight not being supported by the vehicles suspension/springs) you can remove, the better your vehicle will handle and ultimately perform on or off the racetrack.
What Are Floating Rotors? : 2-piece brake rotor construction not only allows the rotor assembly to be significantly lighter, but it also allows for a fully floating "Rotor Ring". Any standard one piece rotor and even 2-piece bolted rotor are fixed to each other with no expansions or contraction movement allowed. As your cars brake rotor heats up they expand. A hot brake rotor ring will have actually grown slightly larger in diameter than when it was cold. The rotor hat also grows as the rotor heats up. This heat cycling, over time, leads to the brake rotor weakening & ultimately cracking or warping. Girodisc floating rotors use a drive pin and spring clip assembly with an elongated hole in the ring so the hat and the rotor can expand and contract freely and un-opposed to one another. This allows racers to run the rotor through countless heat cycles without the risk of warping or cracking their brake rotor.
So that about covers it. If you want a rotor that can withstand heavy repeated track abuse that uses the same technology as dedicated track stars like Porsche GT3 Cup, Ferrari Challenge, Lotus Elise Cup etc... then these are your ticket.