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Discussion Starter · #21 ·
@SoCalS5 good investigation work on all of this, it could be due to brake force modulation.

Something interesting is that while installing the 390mm rotor, it felt lighter. The original S’s are quite heavy.
 

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....Something interesting is that while installing the 390mm rotor, it felt lighter. The original S’s are quite heavy.
That's an interesting observation, and it would be good to know the weights of the various OEM rotors.

It makes me wonder if Porsche targets a certain amount of mass in order to achieve the heat dissipation they're looking for, and with the 390mm rotor they were able to reduce the weight due to the increased rotor surface area for heat transfer, and a desire to minimize any increase the rotational momentum. That's a good question.

For anyone wanting to reduce the weight of their steel rotors, there are two piece floating rotors out there, but they can be very expensive. Anywhere from $700 to $1400 for a pair. And unfortunately, there are not a lot of options available for the front 350mm and 360mm sizes.

GiroDisc is perhaps the gold standard of light weight steel rotors. And while they don't list anything on their website for the Macan, several of their Audi rotors are compatible with the Macan. Unfortunately, GiroDisc doesn't publish their rotor specs on the webpages, so it takes some effort to figure out what's compatible.

For the front, the only GrioDisc option I've seen so far is the 390mm rotors for the Audi C7 RS6. I'd just confirm that the rotor hat height is 52.2mm before ordering. I know that the C7 S6/S7 400mm rotors have that hat height , so I'm guessing the C7 RS6 rotors do too. $1400 a pair.

Girodisc Audi C7 RS6 RS7 2-Piece Floating Brake Rotors

For the rear, GiroDisc has 330mm rotors for the Audi B8 S4/S5, and VoshMods contracts with GiroDisc for the 356mm rear rotors. $800 & $1275 a pair respectively.

Girodisc Audi B8 S4 S5 Rear 2-Piece Floating Brake Rotors

VoshMods Exclusive 356mmx26mm REAR Rotors

I've read that GiroDisc will do a special production run in any size if you order a minimum of 10 sets. So that would take a group buy, or a vendor that's willing to make the investment and sell them on their website.

Just leaving this information here in case it's beneficial to someone in the future. Easier and cheaper to stick with the Porsche OEM setup.
 

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Regular front discs for all but the Ceramic and Performance Pack cars are cast iron - including the mounting bell part of the disc where it fits over the hub. The mounting bell part of the PP discs is alumuinium (see happy snap #3 above) and the disc mounts to this bell by some steel axial pins that allow for heat growth, there is also large air gap in this area - this probably accounts for most of the apparent difference in mass. But I am guessing @Davin did not measure the difference in weight, he just wanted to get the job done and try out the new brakes. ;)

Another way the discs can be lighter, is the size of the ventilation slots (wider discs have wider slots) and the number of vanes used in the slots - race brakes will use this method to adjust the cooling of discs so the pads work more effectively (hot dry races compared to cooler wetter races). They can also swap curved vane discs around side to side so the cooling rate is reduced on a cool day and/or for easier (lower braking) tracks - race pads work best in selected heat ranges depending on compound.

The different boosters listed, is probably related to the different number of pistons and the size of the pistons in the front calipers - more pistons that are larger will need a larger diameter master cylinder to displace more fluid and they will also require more boost (line) pressure to give an equal pedal feel - ceramic brakes in particular. Of course it's vice versa for smaller or less number of piston calipers.
 

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Discussion Starter · #26 ·
@muncie in my case, the new rotors have aluminum hats, while the stock Macan S are iron.

In general, rusted iron will be heavier than untrusted due to the added oxygen mass. However, rust will corrode iron and disintegrate it, so less weight.
 

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Couldn’t you just add a spacer on the calliper to fit the 390mm rotor instead of buying a whole new caliper? Like its still the same caliper right ? Just with a longer space from the knuckle am i correct ?
 

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Discussion Starter · #30 ·
Couldn’t you just add a spacer on the calliper to fit the 390mm rotor instead of buying a whole new caliper? Like its still the same caliper right ? Just with a longer space from the knuckle am i correct ?
@Muckman Maybe, but spacers can be quite a risky endeavor. Proper spacer sizing and structural strength can be hard to achieve, and I don't have access to a machinist.

• It's the same caliper minus the additional mounting length.

If you know of anyone creating spacer, hit me for the rear caliper.
 

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@Muckman Maybe, but spacers can be quite a risky endeavor. Proper spacer sizing and structural strength can be hard to achieve, and I don't have access to a machinist.

• It's the same caliper minus the additional mounting length.

If you know of anyone creating spacer, hit me for the rear caliper.
It literally wouldn’t be that hard. Plenty of 911 owners are doing this. If its the same caliper im just going to make a spacer. If the caliper is the same size then there is absolutely no reason to buy new ones
 

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Discussion Starter · #32 ·
@Muckman unless money is burning a whole in your pocket or someone can supply you with details about the calipers 😉

Go for it and let us know how it goes, I would like spaces for the rear calipers
 

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....If you know of anyone creating spacer, hit me for the rear caliper.
Are you looking to change from the 330mm rotors to the Turbo 356mm rotors for the rear? In that's the case, you can just swap out the rear caliper carriers. They are a bit pricy new.....around $250 - $300 each. But you can sometimes find used ones on eBay for a lot less. See the following thread for the Turbo rear caliper carrier part numbers......

GTS to turbo rear brakes
 

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@Muckman unless money is burning a whole in your pocket or someone can supply you with details about the calipers 😉
I can lend some insight and geometry here ..

Top to bottom:
410mm (new Panamera Turbo iron setup)
390mm (old Panamera/Cayenne Turbo iron setup)
360mm (standard Panamera/Cayenne iron setup)

Look closely, the 360mm calipers are a different casting. They don't fit much over that, as they start to get squeezed off the rotor like a beanie. Thus, the pads will start to pull off the rotor. Some of the features that I look for to separate them are:

1) The height of the ridges. The 'turbos' are smoother.
2) Distance from bleeder shoulder to face outline. There's a ~12mm flat on the turbos between the bleeder face/shoulder and the edge of the 'faceplate' outline. The standards have bleeders that originate right out of the end of the face, so to speak.

As for the 410/390 difference, it's the same general casting, but the legs are longer. I believe the new 410's are very similar to the yellow CCM/PCCB (whatever you want to all them) units from years past. Spacing the 390 to get to a 405 or 410mm rotor shouldn't be an issue. I wouldn't sweat putting shear on one more slip plane. Just use steel, and make sure you encompass the full foot area. You can sandblast the surfaces for more 'key' if spacers will keep you up at night.

Volume: All of them have 36mm pistons and the same radial mounting span. So, getting back to the MC/booster issue, there should be no change in pedal feel at all. The upgrade in stopping power comes not from a change in compression, but from the application of the compressive force on a longer lever arm (diameter).

As for bias, grab some Macan Turbo rears or the 356mm rear setup from an S6/S7 and you should be right back where your were (+/-%). (Careful, the S8 won't do because they get 356 by way of a different spindle with the use of a 330mm rear caliper). Leaving the rear alone shouldn't really be an issue either, since the bias will move forward with the PP/390mm front end. It's usually bringing the bias rearward that starts to bring safety into question for obvious reasons. Still, all said and done, there's a lot of wiggle room here, especially with modern ABS/TCS backing you up.

My .02 and a few legit dims. I hope it was helpful in some way.
 

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That's an interesting observation, and it would be good to know the weights of the various OEM rotors.
Rotor data. Largest to smallest. (Front to rear).
 

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