my post was not clear. first question is the 997 turbo from rotor the same as the 996 gt2 front rotor, the same question for the back. also is the gt2 back caliper the same as the c4s back caliper except for a built in 10 mm space to accomadate the 350x 28 rotors?

997 turbo front rotor differs from 996 GT2/3 rotor. While the caliper is the same, turbo ( read 4WD ) front rotor has different "hat depth" than RWD front rotors. Parts are interchangeable so that you can use turbo rotor on a RWD front axle with 1.5 mm shim between the rotor hat and wheel hub ( to get it centered to the caliper ), but you are not able to use RWD front rotor on a 4WD front axle. At least not without a fitment issue. BUT I know ( and have also seen ) that it has been done...rotor will touch caliper's "pins" ( = ie. it is not centered corrcetly ) and to avoid that pins have either been grinded or hammered in...scary.

I do not have any knowledge about C4S's rear calipers, but a wild guess is that while C4S has the same brakes than a turbo, rear calipers will equal turbos' ones and thus also GT2's.

I have 997 Turbo discs and calipers front and rear on my 996T. They are a complete bolt on and give you you larger 350mm discs and 6 pot front calipers. The fronts are the size as the 996 GT2/3 but have a 2mm different offset.

There are 2 ways to do this:

1. get 350mm rotors and get the Vivid caliper spacer so that you can run your stock front/rear calipers on the larger discs

2. Retrofit the entire 997 Turbo front/rear brake setup to the 996T. Make sure you use the bolts that come from the 997T since they are longer than the factory 996 caliper bolts.

I find that the entire 997 system works very well, but due to increased hydraulic requirement the brake pedal needs ever so much more travel. You can get around this by

1. Sticking to the vivid setup that uses stock calipers with larger discs.
2. Upgrade just the front calipers/discs (the 6 GT2 and GT3 use the same master cylinder as the turbo) so that should work great.
3. Upgrade to the 997 brake setup all around and maybe haven't looked into this yet, upgrade the brake master cylinder to the 997 model?

PETE--- thank you for the inflormation: if i read you corectly i could use the gt2 calipers all the way around (bolt on/without mods). i could use the gt2 rear rotors with out any fitmnet issues but would either have to get the 997 turbo ft rotors or use the gt2 with the 2 mm spacers behind the hats. is this correct? the brakek peddle would have slightly more travel because of the 6 pots up front? thank you again

where is the best place to get 997 turbo front rotors for street use? sunset porsche?

pete is see you cannot use the gt2 ft rotors on a c4s becasue it would be out oo far correct? thank in advance mike

would it be possible to somehow fit the bigger, 380mm rotors, from a 997 GT3 on a 996? has anyone done this before?

Not correct.

4-piston calipers from 996 turbo and 6-piston caliper from a GT2 ( or GT3 or 997 turbo ) have exact the same piston area and thus the same volume, it's just divided in a larger effective pad area in 6-piston caliper.

The same main cylinder will do the job just fine.

GT2 / GT3 mkII / 997 turbo calipers all around.

GT2 / GT3 mkII rear discs.

997 turbo front discs.

OEM master cylinder, if it has the same #number than turbo's one ( if you're planning to upgrade a C4S ). I did the upgrade to my C2 with following parts:
997 turbo calipers, pads and discs ( at front with 1.5mm spacer )
996 turbo MC ( C2's own is smaller ) and booster
996 GT2/3 front wheel carriers

Braided stainless hoses, Motul M600 brake fluid etc

Yes, that's correct.

pete
the c4s master cylinder must be smaller also? do you need the 1.5 mm spacer on a c4s 997 , if you use 997 rotors? are you sure you can use 996 gts back rotors on a 997 c4s? thanks in advance mike, did you get the 997 rotors from porsche? do other people sell 997 rotors , i dont race the car just street use (example vertex)

my phone # 206 920 0332,petrporcheman@aol.com

This is accurate from what I've read. However the 997T rear calipers utilize larger pistons and thus afffect pedal travel.

I have this setup on my car. You will feel a slightly spongier pedal with more travel. One simple fix is to upgrade only the fronts.

Ari you're correct, it seems that 996 turbo's rear calipers have 30 & 28mm pistons while 997 turbo has 2x 34mm pistons, that's significant difference.

Technical manual should state the size of main cylinder, 996 turbo's one is 25.4mm for both front & rear, stroke is 18mm.

Where do I get the 1.5mm shims for this upgrade?