Girodisc upgrade on 991 GTS with Centerlocks
#76
Ditto what mdrums said. I do the same. The stock calipers don't need to be changed.
#77
A1-032 Girodisc
I installed the A1-032 Girodisc on the front end of my coupe and upgraded to GT3 brake pads, and A2-032 rotors in the rear with OEM pads. Kit comes with longer caliper bolts and 12mm spacer for rear setup. The large front six piston calipers allow for large diameter rotors. The kit also came with new front caliper bolts (OEM size); rear caliper bolts are longer than the OEM bolts. There is sufficient room where the Girodisc rotors will not rub on the calipers and the GT3 pads sufficiently cover the surface area on the front rotors.
OEM FR Rotor Diameter: 340mm
Girodisc Fr Rotor Diameter: 350mm
OEM Rear Rotor Diameter: 330mm
Girodisc Rear Rotor Diameter: 350mm
A1-032 - Front Rotors (350mm) with GT3 Pads
A2-032 - Rear Rotors (350mm)
OEM FR Rotor Diameter: 340mm
Girodisc Fr Rotor Diameter: 350mm
OEM Rear Rotor Diameter: 330mm
Girodisc Rear Rotor Diameter: 350mm
A1-032 - Front Rotors (350mm) with GT3 Pads
A2-032 - Rear Rotors (350mm)
The following users liked this post:
Martin S. (09-02-2023)
#78
Rennlist Member
Thanks for the info. I'm getting my new to me 991.1 GTS prepped for some time trials work. I'm sticking with OEM for now, but these upgrades might be my next step if they don't hold. I'll put fresh SRF fluid in there and I'm pretty easy on brakes as a driver (all they do is seem to slow you down). I can usually go a whole year of races in my E36 on one set of pads, haven't changed the rotors in a few years. Slower, lighter car though of course.
#79
Rennlist Member
Great and informative posts.....but t seem the I am confused (Again).
But what is the function or the five (5) studs on the inner side of the hat? Haven’t had the wheels off my 2017 991.2 GTS in over a year and I am confused about the purpose and function of these 5 studs. Also, what is the size of the Allen wrench the fits these studs? And what is their correct torque setting?
But what is the function or the five (5) studs on the inner side of the hat? Haven’t had the wheels off my 2017 991.2 GTS in over a year and I am confused about the purpose and function of these 5 studs. Also, what is the size of the Allen wrench the fits these studs? And what is their correct torque setting?
#80
Rennlist Member
This may be a duplicate post, for give me if hat is the case.
Getting ready to buy a set of front A1-032 rotors for my 991.2 Carrera GTS.
I am, wondering about the the function or the five (5) studs on the inner side of the hat? Haven’t had the wheels off my 2017 991.2 GTS in over a year and I am confused about the purpose and function of these 5 studs.
Also, what is the size of the Allen wrench the fits these studs? And what is their correct torque setting?
Getting ready to buy a set of front A1-032 rotors for my 991.2 Carrera GTS.
I am, wondering about the the function or the five (5) studs on the inner side of the hat? Haven’t had the wheels off my 2017 991.2 GTS in over a year and I am confused about the purpose and function of these 5 studs.
Also, what is the size of the Allen wrench the fits these studs? And what is their correct torque setting?
#81
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#82
Rennlist Member
More on Floating Rotors
My friend Bobby G sent me this. I can't seem to upload the pic he refers to, but you get the idea. I'll continue to try uploading the pic.
It's somewhere in the link below.
See how the brake'sAluminum Hat and Rotor Ring are coupled together by "T-Bobbins" that allow some "float" motion between the parts. This float allows the disc to expand radially and laterally when heated. The amount of motion is small and indicated in RED. This helps to maintain the shape of the disc minimizing cracking and improving overall brake feel as the rotor heats up.
ALSO the float the disc to remain centered in the caliper under suspension loading in corners - this is all important for trail braking feel.
The Wafer Springs take up the float slack so the system doesn't rattle in use. The original 930 Turbo discs were fully floating and the noise complaints made Porsche start using solid bolted hats without bobbins.
Anyone who can't wait, I can email the pic to you....send me a PM if you want it. The info on file with chamerly@apexperformance.net He is my GiroDisc "hero" and dealer. This guy is epic.
t-bobbin-floating-brake-rotor-1788533714.jpg
t-bobbin-floating-brake-rotor-1788533714.jpg
It's somewhere in the link below.
See how the brake'sAluminum Hat and Rotor Ring are coupled together by "T-Bobbins" that allow some "float" motion between the parts. This float allows the disc to expand radially and laterally when heated. The amount of motion is small and indicated in RED. This helps to maintain the shape of the disc minimizing cracking and improving overall brake feel as the rotor heats up.
ALSO the float the disc to remain centered in the caliper under suspension loading in corners - this is all important for trail braking feel.
The Wafer Springs take up the float slack so the system doesn't rattle in use. The original 930 Turbo discs were fully floating and the noise complaints made Porsche start using solid bolted hats without bobbins.
Anyone who can't wait, I can email the pic to you....send me a PM if you want it. The info on file with chamerly@apexperformance.net He is my GiroDisc "hero" and dealer. This guy is epic.
t-bobbin-floating-brake-rotor-1788533714.jpg
t-bobbin-floating-brake-rotor-1788533714.jpg
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Martin S. (09-03-2023)
#85
Rennlist Member
I just ordered a set of from GIRO DISC rotors from my 2017 991.2 GTS from Apex Performance, specifically from Clark (chamerly@apexperformance.net). He is drop shipping these to me in San Diego from GIRO located in WA state. As mentioned earlier by me and others, Clark is very helpful.
Cost? At $1,300 list price a set, they are more expensive than OEM, but the performance benefits more than make up for the increased cost. Also, keep in mind, .the GIRO rotors are available separately, reuse the hats, for $850, which includes new mounting pins. Next upgrade, get GIRO rear rotors.
I have had GIRO front rotors in the past, on my former 2004 GT3. Had the car on the rack on many occasions, excellent brake performance and no possibility of rotors cracking. The lighter weight is always a positive.
Update, I just received my new front Giro Disc rotors. As Sidvicious7 mentions in an earlier post, the new rotors come with 2 sets of front caliper bolts. Now that's a nice touch! My DIY partner and I are installing the Giro Disc rotors soon. I can hardly wait.
Cost? At $1,300 list price a set, they are more expensive than OEM, but the performance benefits more than make up for the increased cost. Also, keep in mind, .the GIRO rotors are available separately, reuse the hats, for $850, which includes new mounting pins. Next upgrade, get GIRO rear rotors.
I have had GIRO front rotors in the past, on my former 2004 GT3. Had the car on the rack on many occasions, excellent brake performance and no possibility of rotors cracking. The lighter weight is always a positive.
Update, I just received my new front Giro Disc rotors. As Sidvicious7 mentions in an earlier post, the new rotors come with 2 sets of front caliper bolts. Now that's a nice touch! My DIY partner and I are installing the Giro Disc rotors soon. I can hardly wait.
Last edited by Martin S.; 09-09-2023 at 07:03 AM.
#86
Rennlist Member
Update, I just received my new front Giro Disc rotors. As Sidvicious7 mentions in an earlier post, the new rotors come with 2 sets of front caliper bolts. Now that's a nice touch! My DIY partner and I are installing the Giro Disc rotors soon. I can hardly wait.
The 991.1 GTS rotor can be made to fit, but that requires adding additional 3 mm spacers added to the four (4) GiroDisc custom caliper bolts, added to the 6 mm spacers that are sent with the 991.1 kit. As I have mentioned in other related threads, GiroDisc and Clark at Apex Performance took good care of feeble me. They replaced the "wrong" front rotors with the correct front rotors. They have been installed on my 991.2 Carrera GTS, and the incorrect correct are in the process of being returned.
Last edited by Martin S.; 10-30-2023 at 10:35 AM.
#87
Racer
This thread is full of great information.
Girodisc all around + GT3 pads for fronts could be the next upgrade for me.
Does anyone know if Giro+GT3 pads squeal like race pads or are they are quieter, like stock GTS setup ?
Girodisc all around + GT3 pads for fronts could be the next upgrade for me.
Does anyone know if Giro+GT3 pads squeal like race pads or are they are quieter, like stock GTS setup ?
The following users liked this post:
Martin S. (10-30-2023)
#88
I for one can say, the noisiest squeal I have had to experience was with the stock rotors and stock pads. Maybe it was a factor from my heavier Targa 4 GTS.
I have found great success in quiet brakes by lubricating 2X per year (Spring changeover to summer wheels/tires and Fall changeover to winter wheels/tires) with anti-squeal grease on all contact points of the pad;: back of pad and caliper piston contact points, and rim of frame of pad where it makes contact with caliper springs.
#89
Racer
Read around in the forum. There are various factors that contribute to brake squeal.
I for one can say, the noisiest squeal I have had to experience was with the stock rotors and stock pads. Maybe it was a factor from my heavier Targa 4 GTS.
I have found great success in quiet brakes by lubricating 2X per year (Spring changeover to summer wheels/tires and Fall changeover to winter wheels/tires) with anti-squeal grease on all contact points of the pad;: back of pad and caliper piston contact points, and rim of frame of pad where it makes contact with caliper springs.
I for one can say, the noisiest squeal I have had to experience was with the stock rotors and stock pads. Maybe it was a factor from my heavier Targa 4 GTS.
I have found great success in quiet brakes by lubricating 2X per year (Spring changeover to summer wheels/tires and Fall changeover to winter wheels/tires) with anti-squeal grease on all contact points of the pad;: back of pad and caliper piston contact points, and rim of frame of pad where it makes contact with caliper springs.
#90
I don't do track driving but normal driving (citw, motorway) and spirited drives on back roads.