There is a lot of "mis-information" out there about what will and won't work with the 996TT and it would be nice to have all the info in one thread...

For instance:

Front Brake Issues
GT2/3 Calipers - Direct bolt on
GT2/3 Rotors - NOT a direct bolt on.

To be able to use the GT2/3 Rotor, which is a different offset than the AWD Turbo Rotor Hat, you would need to replace your suspension upright (The part the strut and hub/axle and balljoints/Tie rod connect at) would have to be replaced. This is a DIY that could be done, but an alignment would be needed and these suspension uprights are not cheap.

Alternatives for the OEM wheel? Unless you have a custom brake hat made, the only alternative is to run the 997Turbo brake Rotor with the GT2/3 caliper. The 997 Turbo rotor is 350MM and clears the OEM 18inch turbo wheel, as does the OEM GT2/3 caliper.

What about the Performance Friction Option??? Nope. PFC does NOT offer a Turbo offset hat in their popular rotor setup.

I'll add more to this thread later, but there is a host of mis-information concerning the brake systems, aftermarket kit wheel clearances, and other areas that need to be addressed, including brake lines and types of fluid, along with pad issues...

UPDATE!!!
OEM Options for plus sized brake systems...

UMW - Kevin sells the complete 350MM front and rear OEM 997 rotor and the updated 997 Calipers in a kit. This kit is remarkable in several areas. First, all parts are OEM upgrades, so servicing the systems is a non-issue if you want to retain Porsche OEM parts. Second, the caliper redesign is impressive, especially on the 997T Rear caliper, which is slightly larger and has a new center bridge to aid in stopping caliper flex. The front calipers are standard GT2/3 fare, which is superior to other designs and fits under the OEM turbo wheel. Check with UMW for specials and availability, but this kit is truly the "whole" package and you won't save a dime putting it together yourself, trust me, I tried.

Suncoast - Suncoast offers a front package of the 997T front 350MM rotor/gt3 6piston caliper. It's all Porsche OEM and a decent "start" of an upgrade. This kit will clear the OEM turbo wheel. Check with Suncoast for this kit... The price difference between the suncoast kit and the UMW kit doesn't save you anything if you eventually want to upgrade the rears as well. You'll spend more money in the longrun on the rear setup by purchasing it later.

AFTERMARKET Options
BREMBO big kit 355 MM brake kits. These kits are well made, massive calipers with additional bracing to fight caliper flex, and lighter two piece rotors. The issues with these kits revolve around wheel clearance (none of them clear the OEM wheel) and pad choices *(apparently there are few selections in compounds).

Rotora Brake kits can be had in several plus sizes, including two different configurations for calipers, both four and six piston. The same warning as with the Brembo brake kit applies. Be careful of wheel fitment.

Wilwood Brake company supplies some of the largest and most aggressive systems for raceteams world wide, and are used by many popular teams. They will put together a kit to suit your needs. Beware that their calipers are much bigger than the OEM stuff, and wheel clearance will again be an issue.

For rear axle:
If you won't care about retaining your emergency brake, you can swap your rear rotors to a two piece design as well, and plus them up. Otherwise your only plus sizing for the are the 997 Turbo rotor, and either using your 996 Caliper with a 12MM spacer and 997Turbo bolts, or going to the $1100 997Turbo calipers along with the 997Turbo rotor.

Floating Vs. Fixed two piece rotor design:
Our calipers are a "Fixed" calper design. Using a "fixed" rotor, which our OEM rotor is, adds stress to the overall braking system. It also adds more weight to the rotor. By going with a floating rotor, you will reduce weight, and allow for slight deflection in the rotor as the materials expand and contract under constant heating and cooling. The down side to the whole "floating" rotor design is the noise. On a road going car the noise of the rotor floating in the hat can be a tad bitt annoying.

Rotor "ONLY" options:

Coleman Racing ( www.colemanracing.com ), Stock Car Products ( www.stockcarproducts.com ), and a host of other race car fabrication companies will make you a rotor to your specified size. I've dealt with both companies over the years in a previous life making and selling suspension parts for another platform. Both companies support the hobbie/grass roots guys with tight budgets. They can make you a rotor to your specific offset, thickness, size, and type: solid/slotted/drilled - You tell them what you want and they make it!



This is a Coleman Racing rotor made for another Rennlister that eventually sold the setup to me... I've tracked with it with great success and low rotor/pad wear so far. It used an 8inch 12 bolt rotor hat custom made of aluminum. Mine is a fixed rotor design, since I still drive the car on the street. The hats cost about $550 per pair and the rotor replacements are about $350 per pair plus hardware (12 rotor bolts each) and shipping. The rotor I use is directional vein vented and slotted.

You could certainly get a 330MM stock sized vented rotor made up to replace the OEM 996 Turbo units, keeping the cost down, and run these with the proper pads and brake fluid and have a respectable performer in the brake department.

Pad material choices can impact the life of your rotor. Do your research and talk to those who have experience with various types of pad material. Choosing the wrong pad will shorten the lifespan of your rotor, as the aggressive pad material will eat the rotor quicker. I prefer pagid yellows, and feel that if they're good for a 24 hour of LeMans race, they'll last me quite a while. Porsche uses these pads due to their rotor-friendly nature. Again, good enough for LeMans, Good enough for me!

COOLING THESE BRAKES!!!
One area the OEM brake system suffers in is boiled fluid. Below is a list of the more common performance fluids and their boiling points.

Brand Wet Dry
Castrol SRF 518°F 590°F
Motul RBF600 420°F 593°F
GS610 417°F 610°F
AP-600 410°F 572°F
Brembo LCF 600 399°F 601°F
ATE-Super Blue 392°F 536°F
Valvoline 333°F 513°F
Castrol LMA 311°F 446°F
Ford HD 290°F 550°F
Wilwood 570 284°F 570°F
PFC-Z rated 284°F 550°F
AP-550 284°F 550°F

Most race shops recommends Castrol SRF or Motul RBF600 or Brembo LCF 600 due to their high wet boiling points. All brake fluids absorb moisture, some faster than others (except silicone which is not recommended for anti-lock brake systems). Castrol SRF resists moisture contamination (non-hygroscopic) more than any other fluid tested, therefore change intervals can be greatly extended. This reduces the effective cost over a season of tracking. Many drivers say that they can run the same fluid all year long with only bleeding off the fluid in the calipers for each event. This way a can or two will last all year. Other fluids (hygroscopic type) require additional flushing of the system for each track event to maintain the lowest percentage of moisture and the highest boiling point. For cars over 3000 pounds on high speed road courses every race race engineer I've spoken with recommended brake fluids that do not fall below 400°F wet boiling point. I prefer to bleed my brakes before each weekend and I personally use Motul, due to the cost per bottle. I don't like to open a bottle of brake fluid and then re-use it 30 days later, because I'm concerned about the hygroscopic nature of brake fluid and the amount of moisture in the air. Once you open a container of fluid, it should be used and discarded. Others will argue this, but brake performance is one area I don't mess with... $20 worth of discarded fluid after a bleed is worth it to me... I use it over the course of a weekend and then chuck the unused remains.

Brake cooling goes beyond fluid. You need cool air to duct into the area of the brake/wheel assembly to cool the rotor/caliper/pad/wheel bearings/balljoints... yup, your suspension benefits from cooler air... Next time you have a wheel off, notice the heat shields Porsche designed to help stave off heat soak... Fresh air helps all the way around...



My DIY brake cooling ducts I originally used... These worked effectively but hung down to low and were dragged on speed bumps or other "stuff" that wasn't flat. I've since replaced that system with the GT3RS race cooling ducts made by Porsche. They also hang a little low, but will perform well and get more air into the wheel housing than the stock 996TT units without the hose/ducting route issues.

Brake lines: A popular "upgrade" on many platforms is braded brake lines. I am not so sure that the OEM porsche brake lines need replacing. When I spoke with a couple of race shops, they adviced that the lines fromt he factory were more than sufficient and many left them alone... I bought some steel braded lines from Pelican Parts with the intention of installing them, but opted out after the several discussions with shops who had success without swapping...

One area you must be aware of is pad wear. Do NOT let your pads drop below 1/4inch of thickness if you track your car. The amount of heat generated when tracking your car is more than the 1/4inch of pad material can protect your piston cups/seals from.

Tools of the DE trade...

I recommend bleeding your brake system before each event. A motiv pressure bleeder is an excellent "one man" tool to aid in bleeding in a very short period of time. Along with that, I use a catch bottle from CDOC and I bleed the circuit from right rear, inner bleed screw, to right outter bleed screw, then left rear inner to left outter, right front inner bleed screw to right front outter, then left front inner blled screw to left outter. I generally don't pressurize my Motiv beyond 14# and I never use the system to "add" fluid. I simply top it off at the end of the bleed.

Mike

 

Mike great post!!! Next get together I need to come over and check your brake set up out. I would really like to see your cooling set up.

 

mike - great write up! Can you explain why going to a two-piece rotor in the bake sacrificies the ebrake?

 

Great write-up. What about weight savings? Do you have the weights for all these rotor options. I think that is more important that stopping power for those of us who don't track our cars. Thanks

 

I refuse to support internet brands
Mike

 

Subscribed! Great post, thanks!

I am researching for an upgrade in the near future...

 

Excellent Post and suggestion on a sticky thread.
Thank you for spending your time to put all the info together.

 

One good mentioning is that the 997TT brake kit with its calipers and disks is a direct bolt-on for the 996TT. There are some sets lying around because people changing to PCCB's in their 997's due to weight saving.

I have the full GT2 6-pot front kit from Manthey-Racing. Modding the suspension uprights was not needed. Only the pins in the calipers needed to be modded a bit because the wheel hubs are different in the Turbo because of the 4WD.

Anyway I have those in GT2 specs going to my car next. Hope they last!

I'm using these Pagid Yellows myself (have tested both RS19 and RS29) and the Porsche rotors do not last long with those! They start to crack really easily (both 330mm TT and 350mm GT2) after some hard track driving.
That's why I am trying next the PF rotors. And yes I got some additional cooling (the GT3 Cup brake ducts)...

But don't be too afraid of cracking the rorots - with Pagid Yellows the brake bite is really excellent!

One worthwhile option can be the GT3 Cup disks when using the 6-pot GT3/GT2 system. They are a bit lighter and much cheaper (when bought from Porsche Motorsport) but of course they won't last long in heavy cars like ours.

 

Thanks for all your efforts in assembling this data for us.

 

This is a great thread, thanks for all of the clarifications. Can someone please explain how the 997TT set up differs from using the 6 pot GT2/3 caliper with the 997 rotor. Is there a big difference in the calipers?

thanks
Kenny

 

The GT2 rotors will work if they are machined, I've used them.

 

Mike-great post and thanks...

Just out of curiosity-what symptoms will breaking exhibit when the brake fluid goes bad i.e. has absorbed too much moisture?

 

I refuse to support internet brands

Mike

 

There wont be any symptoms, OR BRAKES




J/K Long pedal, which you really dont notice much in these cars because the pedal feel is pretty bland. But if you have to put the pedal to the floor to stop, time to slow down and take a break, and bleed them even at the track.

 

I refuse to support internet brands

Mike