Checking in for any updates with those that have installed the Girodisc rotors and how this is working on track. I'm finally about ready to order parts and also wanted to see if anyone knows if the compound on the GT3 pads is actually different from the Carrera S pads? I'm thinking about running stock GT3 pads for both street and track as I'm only going to do 2-3 track days a year (famous last words) and don't want to swap back and forth.

Also, any issues removing the rear rotors with the internal parking brake? They were a major PITA on my GT350 so I'm hoping they are much easier to change on the Porsche. I'm probably going to run the Girodisc on the back as well.

Also any of you installing CC plates and if so which ones?

I have Girodisc rotors on the front and rear, Pagid Yellow pads all the way around, and brand new Michelin Pilot Sport Cup 2's and everything worked flawlessly on the track. I still think the weakness of the 991.1 S is the somewhat spongy initial feel of the brake pedal. I've checked a few other 991.1's and they are all the same. The Porsche mechanic told me this is "normal due to the over boosting of the brakes." Once you get through that subtle dead band the brakes are rock solid. Zero fade. When I changed out the rear rotors I did not have any problem with the rear drum brakes for the parking brake. The fit without adjustment seemed fine. After the job was done the parking brake works fine and all is good. I would just make sure you have the large Phillips screwdriver to take out the two fasteners that hold the rotor to the hub. I have a hand impact driver which helped get them out since they were a bit snug. Next time, I know I will have some of these Phillips screws handy to replace them. I put a dab of anti-seize on them when I put them back in to ensure they are easy to take out next time. Hopefully that's a long ways away.

I didn't move to the GT3 pads...the 911.1S Pagid Yellow pads worked fine. Good luck.

Thanks. I have a hand impact and it came in handy when I installed some wheel spacers. The brake pedal is a bit spongy and I'm either going to run Endless or Castrol SRF brake fluid to see if that might firm up the pedal a bit.

Anyone else know if the GT3 and C2S brake pads are different compounds?

I'm not sure how aggressive the GT3 pads are but aggressive race pads can have a grinding sound to them. Hard to believe that a GT3 pad, or any other for that matter, could not be used with Girodisc rotors. They are iron like all the others. Pads typically leave deposits because they aren't bed in properly. Not sure if a GT3 pad needs to be bed but I'm sure it can't hurt.

Still trying to determine the difference in compounds between the GT3 and C2S pads.

Further support to the proposition that, perhaps, I need to bed them in properly even after a track event. Wish I could help about compound. I was sold just on bigger surface area of pad

@mdrums and @zoiks are you using the stock brake lines in the rear with the 350mm Girodisc rotors? Any caliper clearance issues over the studs?

to the OP and others who have caliper studs and got the A1-032 hats- when you say you did not need longer studs, what stud length did you have initially? I have 85mm all around, and don't see how its possible i won't need longer studs by going from a 340mm to 350mm rotor, regardless of the size/shape of the hat. maybe I misunderstood...

For both the front and rear, when i tighten the caliper into place with a washer, I have maybe 2-3 threads showing... so not much left at all in terms of spacing.

I just purchased Giro's, DS2500s and studs from Clark at Apex. He is telling me the front studs are the same as stock but the rears need to be 97mm. Haven't installed yet though.