GiroDisc Porsche 911 Carrera / C4 (991.1) 350mm Slotted Rear Rotors
SKU: 63415898052

GiroDisc Porsche 911 Carrera / C4 (991.1) 350mm Slotted Rear Rotors

Sale price$588.60 Regular price$654.00
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Description

GiroDisc Porsche 911 Carrera / C4 (991.1) 350mm Slotted Rear RotorsSold priced in pairs Welcome to GiroDisc! Brake rotors have long been the overlooked link in performance car braking systems. Traditional 1 piece brake rotors are heavy and retain heat, diminishing their effectiveness and adding unsprung weight that adversely affects handling. When GiroDisc was founded in 2003, we made it our mission to design and manufacture 2 piece brake rotors that would perform flawlessly at the limits. Our fully floating design


Sold/priced in pairs


Welcome to GiroDisc!

Brake rotors have long been the overlooked link in performance car braking systems. Traditional 1-piece brake rotors are heavy and retain heat, diminishing their effectiveness and adding unsprung weight that adversely affects handling.

When GiroDisc was founded in 2003, we made it our mission to design and manufacture 2-piece brake rotors that would perform flawlessly at the limits. Our fully-floating design uses tension hardware to ensure that our rotors are silent on the street, but ready to go on the track.

By specializing in this area, we can dedicate our efforts to push our engineering and manufacturing to the highest levels in the industry. Customers around the world have found success maximizing the capabilities of their existing brake systems by installing GiroDisc rotors. This often negates the need for a pricier, more complex upgrade like a big brake kit.

GiroDisc is headquartered in Bellingham, Washington, where we design, engineer, manufacture and fulfill orders on site.


The primary purpose of the Girodisc system is to reduce unsprung and overall vehicle weight. The secondary purpose is to increase the ventilation and cooling capacity of the brake disc while retaining it's original dimensions. This is accomplished by using two-piece disc construction. The central hat section of the disc is made from 6061-T6 aircraft specification aluminum.

The disc is made from cast iron, to the same specification and material as used by professional racing organizations. It is 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 high strength alloy steel drive pins, manufactured by Girodisc 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 clips 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.


Important Questions Answered

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.

 

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 63415898052

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avalancheryder
Fort Morgan, US
★★★★★ 5
Absolute game changer for chronically dry feet/cracked heels
Size: S (up to size 7)-Beige
I had recently bought a pair of silicone heel/ankle wraps to fill out my boot a little since I noticed my heels were lifting when I was skating. I tested them out around the house and noticed they left my heels softer while the rest of my sockless feet got quite dry. So I got these full foot silicone socks to see the effect of having my whole foot covered. I slather the entirety of my feet with Dr. Scholl's Severe Cracked Heel Restoring Balm (love how convenient it is to apply it to my feet with the solid stick form) and then slip them into these silicone socks. After just a couple hours, when I pull out my feet they're (a teeny bit sweaty at first), but then overall soft and smooth and have absorbed the balm fully leaving barely any residue in the silicone sock. I find these silicone socks generally comfortable; I wear them in the evenings while relaxing on the couch, take them off after a couple hours and let my feet breathe a bit, and then reapply my balm and socks and wear them to bed. If I wake up in the middle of the night, which I almost always do (not because of the socks), I'll take the socks off and allow my feet to breathe again. I wear a woman's size 6 shoe and the small size is pretty comfortable. However, I made the mistake of wearing them while being on my feet for a couple hours straight during household chores -- they must've somehow cut off my circulation a bit with the standing, so I wouldn't recommend wearing these silicone socks while being active. And since they're not exactly my foot size, they slide around sometimes and will start to feel tight at my big toe. But if that happens, I just tug on the toe area of the sock to give my big toe more wiggle room and problem solved. Prior to wearing these socks, I was soaking and doing heavy duty exfoliation of my feet every week. These socks seem like they'll work to help me extend the time between soakings and exfoliations. The 5 pack is a great value. So far none have torn, so they seem rather durable. Not sure what I could even do to tear a hole in these.
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Reviewed in the United States on January 16, 2026
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Beverly Durham
Draper, US
★★★★★ 5
Works wonders
Size: M (up to size 9)-Beige
Works wonders for dry feet, like really dry, hard feet.
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Reviewed in the United States on February 23, 2026
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Therapy by the Sea
Belleville, US
★★★★★ 4
EXCELLENT FEET MOISTURE PROTECTION
Size: S (up to size 7)-Beige, Size: S (up to size 7)-Beige
Why did you pick this product vs others?: I have burns on my feet and needed something that I could put burn creme on and still walk around in with. I tried other silicone footsie but they would teae really easily. So far these are doing really well for this purpose. They are holding their shape too. The only caution I have is the same with all silicone footsies: They can be slippery on wet floors, so also wear with socks over them. The biggest issues is when they say a size they mean it. The silicone used in these have little give in them, so they won't stretch out and loose their shape. That can be a good thing, or not so good, depending on how well they fit your feet and what your intent is with wearing these. The other issue is if they fit snug around those toes, that tends to be where the first tear in the material will happen. Because of how these are made, the tear is actually more like cracking in the material and once it occurs you won't be able to get much use out of the sock after that. If you are planning to wear them around the house or for long term use, I suggest going up a size or look for the toeless options.
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Reviewed in the United States on July 5, 2025
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Shawna
Boise, US
★★★★★ 3
Silicone socks
Size: M (up to size 9)-Beige
The socks are sized large. The quality of the silicone is good. But they slide around on your feet if you try to walk, making them difficult to use and a bit uncomfortable. Unless you are able to sit for long periods of time the likely will not work well. Recommend looking for a better value.
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Reviewed in the United States on October 27, 2024
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Ann
Port Orchard, US
★★★★★ 5
Effective
Size: L (up to size 11)-Pink
Fantastic. I put lotion on my feet & wear them when I go to sleep. I often wake up during the night and will remove them to find my feet soft and smooth. They are strong and fit my size 10 womens’ size.
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Reviewed in the United States on March 27, 2026

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