Girodisc Rear Replacement Rotor Ring Set - E9x 335iGirodisc is a Braking Technology Company dedicated to developing the best quality high performance braking components and solutions. The company has been in business since 2003 and is guided under the direction of company Principal Martin Meade, who spent five years as an Engineer with Porsche Engineering Services, where he played a role in developing current Porsche technology. PRODUCT INFORMATION Need new rings for your Girodisc 2 Piece Floating
Girodisc is a Braking Technology Company dedicated to developing the best quality high performance braking components and solutions. The company has been in business since 2003 and is guided under the direction of company Principal Martin Meade, who spent five years as an Engineer with Porsche Engineering Services, where he played a role in developing current Porsche technology.
PRODUCT INFORMATION
Need new rings for your Girodisc 2-Piece Floating Rotor Set? We got them. Rings come complete with all new hardware and full instructions for re-assembly; but if you choose you can send us the hats and we will do all the re-assembly and turning of the rotors for only the cost of shipping.
This service is available for the life of your rotors. Price is for a pair of rings and 2 hardware kits. Additional hardware kits are available separately upon request.
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
What is required to install the Girodisc system?
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.
How does reducing weight of the braking system benefit the vehicle?
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.
Why slotted discs?
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 doesnotrecommend drilled discsfor high performance 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.
Note as example the cracking in this OE Ferrari 550 drilled disc after one track day. Also note this custom front disc of a Porsche 993 Turbo after hard use (see photos).
Please see photos attached
Should new discs and pads be bedded in and if so, how?
The answer is yes, for optimum performance, any time different friction materials or discs are introduced, a bedding procedure should be carried out.
Which direction should the discs rotate?
For maximum airflow and superior cooling, the Girodisc system uses curved vanes. For a curved vane internally vented disc, the geometry of the vanes dictates the direction of rotation. A curved vane disc must be installed with the vanes running back from the inside to outside diameters in the direction of rotation. Your discs will come with labels indicating their correct placement on the vehicle. Orienting the disc in this manner creates a centrifugal pump. The rotation of the disc causes air to be pumped from the center of the disc, through the vanes, and out through the outside diameter of the disc. This greatly enhances the disc’s ability to dissipate heat. Discs installed backwards have very limited cooling.
I wish my Dad had lived long enough to have this given to him!
Format: Paperback
As I said for Mr. Vansant's Gettysburg graphic novel, this is perhaps the best visual description of all of the planning, logistics, and follow-up battles that gave the Allies their second front, and began the march to Berlin, and the eventual downfall of Hitler's Thousand Year Plan.
I have studied War History for as long as I can remember - focusing mostly of the American Civil War, World War 2, and Vietnam; three of the United States' greatest turning points in warfare - but my Dad and I shared a huge interest in WW2, watching as many documentaries on it as we could. What most people do not know about the importance of the war is that it is one of the few times that most of the world was not only involved either directly or indirectly, but also it is one that everyone - and I mean everyone, from the footsoldiers, leaders, and civilians - knew exactly why and what they were fighting for. While it seems odd to refer to events so brutal as noble, that is the best way to describe World War 2, since most of the world was involved in it, and why.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 7, 2015
R
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RS
Lake Worth, US
★★★★★ 5
10-year-old grandson loves this book
Format: Paperback
I bought this for my grandson who is very interested in World War II. He has just turned 10. He loves the book. It seems to be the perfect balance between text and pictures. He will learn about the experiences of his great grandparents while learning to read at the same time.
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Reviewed in the United States on August 16, 2020
W
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WiltDurkey
Houston, US
★★★★★ 5
A+
Thought it did a really good job framing the big picture, as well as showing some of the nitty gritty details of the fighting that took place. Even though I thought I already knew a lot about D-Day, I still learned some things along the way.
Note: although I do most of my reading on my Kindle Paperwhite, I read this on my iPad Kindle app instead. I don't expect the graphics to come off too well on a non-tablet Kindle so did not even download it there.
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Reviewed in the United States on July 10, 2016
J
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Joe ostrander
Lake Worth, US
★★★★★ 5
Wonderful middle grade book
Format: Hardcover
This book is part historical fiction and part sci-fi. I bought because we like getting the Newberry award winner every year. We loved this story. It was fun read a book placed when I was kid and see/show my kids how much the world has changed, but it also had a fun time travel element. This coming of age follows a kid and his worries about Y2k. He deals with the death of a friend and worries about everything. We loved this story and it's special sections back i to the future making it easy to believe that time travel is real.
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Reviewed in the United States on August 8, 2025
L
Verified Purchase
L. J. Rinaldi
San Leandro, US
★★★★★ 5
Fantastic
Format: Kindle
Time travel books are fun. You have to wrap your head around how they work out in the end. This time travel book sort of sneaks up on you, in that other things are going on while Ridge, the time traveler, is checking out 1999.
For those who were alive in 1999, we all worried about Y2K, when all the computers would stop working. Scientists worked hard to make sure that it wouldn’t, and at the time, only one bank had trouble after the new year began. Other than that, we were all fine, and life went on.
Micheal, is obsessed with Y2K, and when he learns that Ridge is from the future, it is all he wants to know about, and Ridge can’t tell him, as the event is too close. He can tell him how he got his name, and a little about how life is like in the future, but that is about it.
But Ridge is the first time traveler, and he has no idea if anything he says will change things, so he has to be very careful. He has no idea what he will find when she returns home, and so worries about everything he says.
I really enjoyed this book. I marked several passages that spoke to me. And even the title is such a good thing to bring up and explain, in that it means living in the present time. Not worrying about the future or the past.
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