Well...you really should then consider a BIG Brake Kit for the fronts ...with at least 13 inch quality 2 piece rotors. They are designed to run MUCH hotter and are specially tempered. Stoptech Aeros are *True* floating rotors (allow expansion)..as opposed to say Willwoods, which are not. The 332MM (13") are bigger and thicker than the factory Brembos and are designed to dissipate heat much better. You can step up to 14", but that will cost another $500. You can also just get 2 piece Brembo sizes from RACING BRAKE and use your calipers.

 

Been using Stoptech slotted rotors and I never had cracking issues with them on track days. I recently switched to 2pc.

Nismo-Z are you running on R-Comps?

 

No, not running R-Comps yet. Still on OEM Potenza RE050A on the rear and just switched to Michelin Pilot Super Sport XL on the front. I only got 9 track days out of my last set of Potenza's on the front so I decided to try the Pilots with a little better wear resistance. I’m starting to think about adding camber.
I do ok on the street radials, but I can see how the guys on R’s are a little quicker in the corners. Switching to R’s means an extra set of wheels and a trailer to get them to the track.
When I do switch to R’s I think that’s going to mean a little more brake heat

 

yes it will, even just better and wider street rubber will cause more braking heat.

 

OEM Brakes on my 2008 Nismo 350Z
Calipers: Brembo, four-piston front and two-piston rear.
Rotors: 12.8-inch (330 mm) front and 12.7-inch (320 mm) rear.

Size: I would think going to a 13" or 14" rotor from the current 12.8" isn't going to make that much of an improvement. Any thoughts on that?

 

Holes/Slots or Not: Discontinuities, such as holes and slots are areas that concentrate stress that can initiate crack formation and propagation. I think the photos of cracks at my slotted DBAs and Ronn1 cross-drilled rotors at strong evidence of this. The only reason for holes and slots, that I’m aware of, is to improve braking friction by reducing gas pressures between the rotor and pad. I improved friction by going to a more aggressive pad, which most likely comes with added heat.

 

2 Piece Rotor vs 1 Piece: 2 pieces prevent heat transfer to the hub. Good that it prevents overheating of the wheel bearings. Bad that the rotor heat is cut off from another heat sink source, leading to higher rotor temperatures. The benefit of 2 piece might be that can get the ducted cooling air into the center core of the rotor ring and both sides. With the 1 piece, I can only get cooling air on the inner side of the rotor.

 

If you see the design on the 2pc rotors (for example the AeroRotor from Stoptech) you will see the improved vane designs. Also, the gap between the disk and the rotor hat compliments the vane design and this in turn helps dissipation of heat quicker than the oem rotor. It weights about 3kg's less too.

BTW I just got back from our time attack event at Yas Marina and the Stoptechs did pretty good.

 

It's not just the bigger size (thicker too)..it's the rotor design.

 

I have multiple Road Atlanta track days on my 07 Red Nismo, though I have not seen any disc issues like this! I have only encountered excessive heat, but that has been assisted with ATE Super blue fluid and ducts, neither of which would help stop those kinds of cracks so I will be very interested in what you end up using that is working for you. *subscribed*

 

Brake problem solved based on 2 track days at NHMS running the south oval and 3 days at Mt Tremblant. Real test will be Watkins Glen Aug 22-23.

For Rotors I bought both Stoptech 2pc AeroRotors ($650) and Centric High Carbon Plain 125 Series Rotor ($160). Not wanting to chance ruining the Stoptechs, until I'm sure I've solved the problem, I've been running the Centrics with good results.

Biggest improvemt was likely cutting off the dust shields. Temperature indicating paint on the rotors is telling me I had temperatures between 750°C and 1,000°C at NHMS and betwenn 1,000°C and 1,200°C at Mt Tremblant. Caliper temperatues 143°C left side and 166°C right.

The rear rotors and calipers are running hotter than I would have expected. At Mt Tremblant, rotors were betwenn 1,000°C and 1,200°C and both left and right calipers at 188°C. I think I need to remove of cut off the rear dust shields now.

Front brake ducts are the same 2.5" diameter and positioned below the caliper. If I have overheating problems at the Glen, I'll try to reposition them to get more cooling air into the rotor hat.

Pads are still Hawk DTC-60s, Brake Fuild is Castrol SRF and I use Titanium shims

 

If the stoptechs don't work out for you I've got a big brake kit (4 wilwood piston mounted calipers/ rotors/flex hoses/mounting hardware/rotors and pads) I could give you a deal on. Let me know if you're interested, I could give you more details.

 

I haven't gotten around to running my hoses like you did. If you looking for more direct air! Why not use the side markers...

something like the 370Z RC car?

 

Data is your friend.

750-1000 deg F - iron is all good pretty much

Once on past 1200 - all sorts of bad things happen to gray iron. There are many factors - cooling too much on a straight is bad, heating up too quickly, heating or cooling unevenly as well as the gross max temp attained.



-DBA changed the slot design - that lil straight one on the edge was killing rotors. I run DBA 2 piece on my C5 Z06 - w/ DTC70/R6's I got 4-5 times more life out of front rotors. They have regular slots w/out the extra slot.