Cloudspin

Did you notice the brake pads protruding over the edge of the rotor like this at all? [/QUOTE]

Not that I recall. My car is up in Daytona having the PDK replaced, PWR radiators installed and a tune done so I can't go out and look.

Do you remember what size spacers they included for the caliper? (I believe it had a label on the spacer itself)[/QUOTE]

They are 12mm from Girodisc. You're going to love them. I'm switching pads to Race Technologies RE10 endurance race pads based on recommendation from KA Motorsport and RL'er Trakcar's experience with them on his 991 RS. Next weekend will be my first event with them. They are supposed to be a little easier on the rotors and last longer than the PFCs. We'll see!

scorcherjf

Thanks! They had given me 12mm as well so I thought it might've been a mistake but good to know it's the right one.

Also, they came with extended caliper bolts but now you have me a little worried if one came out. Was it hard to switch to a stud and nut for the caliper?

Cloudspin

The issue as I understand it is a steel bolt into an aluminum hub / upright and the possibility of the bolts pulling out and stripping the threads. From the Tarret website:

Upgrade your 986/996/987/997/981/991 with this Cup style brake caliper stud kit. A must have item for both club and pro racing. The factory bolts will quickly strip out the threads in the expensive wheel uprights, from removing the calipers for maintenance. These Cup style caliper studs will eliminate this problem and quickly pay for themselves. They also allow for quicker and easier caliper installation by guiding the calipers into position. Manufactured from aerospace quality 17-4 PH stainless steel for high strength and corrosion resistance. One kit includes 4 studs, nuts, and washers, complete for one axle. Two kits required for front and rear.

Now Available!!! Our Brake caliper stud kits now include the highest quality available, ARP 12-point nuts. This is a no compromise solution. Made from high strength stainless steel, these nuts will not corrode, have a 180,000 PSI tensile strength, and are compact in size for a better fit in the break caliper bore.

See application chart below for size recommendations.

GiroDisc applications: See adaptor kits below. Use GiroDisc supplied bolt length for stud selection.

62mm & 95mm stud kits include PMNA Cup studs. They are made from high strength steel and are black in color (not shown).

There are several suppliers. I'll try to find who I purchased mine from but here's the link to Tarret:
http://www.tarett.com/items/986-987-...csk-detail.htm

Para82

I'm on the same rotors that came from the factory in 2005.

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scorcherjf

Thanks for the info. When your bolt came out, was it the actual bolt that stripped or the threads in the upright? If the upright is aluminum and the bolt is steel, I would expect the upright threads would be the first to go since steel is stronger? Did you remove and re-use the bolts previously? I know the OEM bolts are supposed to be 1-time use because they stretch or something.

Cloudspin

Yes, bolt pulled out of upright under braking and ruined the caliper and upright.

nwGTS

Bringing this back to life and hoping Mike chimes in if he knows.
My GTS has 5 lug and NOT CLs. So I would just be upgrading from C2S parts. As I understand it, a 997.2 C2S can upgrade to six pot calipers using (1) 997.2 GT3 or 997.2 TT calipers for steel brakes but NOT PCCBs and (2) 997.1 TT 350mm rotors for five lug NOT CL because CL have different rotor offset.

Is the above correct?

Secondly, will an upgrade ALSO need a different sized caliper bolt? If so, what size?

Thanks for chiming in. Putting a parts list together for the next upgrade.

semicycler

997.1 C2S here. I did the turbo 6-pot upgrade and 350mm rotors. After sourcing the calipers I went through the turbo PET diagrams and compared parts that were different then used the turbo part numbers. For example, 997.1 C2S front caliper bolts are M12x1.5 77mm long taken from the part number description (999.067.050.09 pan head screw M 12 x 1,5 X 77). Turbo front caliper bolts are M12x1.5 85mm long (999.067.047.09). Do this for any of the parts you will be swapping.

There are dust shields between the rotors and the wheel hub that are larger on the turbo as well. It's not really necessary to change them out but consider it. I also had to fabricate a short section of brake line up front because of the differences in the way it attached to the uprights. Was rather easy to do with standard straight brake lines from the auto parts store and a tubing bender/flarer. The rears just bolted up without issues.

nwGTS

Before I start applying this to my build sheet I was verifying that 997.1 C2S and 997.2 C2S uprights and hubs are the same. Are they? I saw your thread with the above info before and my next steps were to verify they were the same but I couldn't find that info.

Essentially, if we can verify 997.2 and 997.1 C2S brakes are the same then I'll just copy/paste this which would make this part of the process a lot easier.

semicycler

The OP wanted larger front brakes. He started his journey by swapping the wrong piece, the rotors:
Correct - the calipers are interchangeable with the proper mounting bolts but the rotors have different offsets between 997 NA/turbo and GT3.

Yes the offset is different for a GT3 only. GT3 calipers and Turbo calipers are interchangeable but the rotors are not because of the upright offset difference. The GT3 rotors do not fit a NA or turbo 997. With two piece rotors the outer rings are interchangeable with GT3's but the inner hats are not (different offsets). You need 997.1/997.2/Turbo hats. GT3 hats do not fit. To answer directly, keep your 350mm two piece rotors and install the GT3 6-pot calipers or Turbo 6-pot calipers. Either of these two 6-pot calipers will sweep the entire area of the rotor - no more 20mm inner unswept ring.

Yes the uprights are the same part number 997.341.157.25 between 997.1 2S and 997.2 2S. Technically the 2S vs 4S uprights are different part numbers but the caliper mounting holes and rotor offsets are the identical in this case. There are minor differences in the 997.1 base models too but again the caliper mounting holes AND OFFSETS are the same between 997.1 and 997.2 NA/turbo. It's the GT3 upright offset that is different.

As for hubs all 5-bolt pattern hubs all have the same mounting points between all 997's and 996's, maybe even other series too (71.6mm center bore, 5x130mm bolt pattern). This means 5-bolt pattern wheels and spacers are interchangeable provided the wheel offsets are similar. GT3 wheels fit non-GT3 cars unlike the rotor problems.

One other note: master cylinders are different between the 4-pot and 6-pot brakes. Most do not change them out during a bigger brake upgrade. But consider adding it to your list or upgrading when servicing anything in the brake lines (swap the master if the slave fails).

TL;DR: Calipers are interchageable using the correct caliper bolt length. Match the rotor size to the caliper (330mm vs 350mm). But rotor offsets are different for the GT3. So to step up to 350mm brakes on a NA 997, use turbo 350mm rotors only. Then either put a spacer on your original calipers (leaves an unswept area on the rotor) or swap to turbo or GT3 larger 6-pot calipers (full rotor sweep area coverage).

nwGTS

^^^^Terrific explanation, thank you.

Petza914

I swapped 997.1 PCCBs and Big Reds between 2 997.1 C2S cars so a 4-piston caliper onto an original 6-piston car and vice versa and left both master cylinders alone - both cars drive and brake perfectly.

Cloudspin

I'm approaching 80k miles on mine and am considering proactively having the calipers rebuilt and replacing the caliper studs and s/s braided lines (both 4 years old and over 80 track days). Current brake setup is one of the strongest aspects of my car but 80k is 80k and am open to adding the master cylinder to the list. Can you share the part # of the 6-pot master cylinder? I did a 1/2 a$$ search a couple months ago and came up with the same part # for .2 C2S and GT3. Thank you!

semicycler

The one you want is 997.355.910.30. When in doubt use the Turbo S version for the closest model year you have.

997 C2S uses 997.355.910.10. It looks like the C4S/Targa S/Turbo/GTS/GT2/GT3 already have the correct part 997.355.910.30. There are some variations on this for base models or if you have the ceramic brake package option code I450. So you only would need the upgraded master cylinder if you have a base C4 or a NB C2/C2S.