andrewhake

Nothing at all wrong with those rotors. Use a better pad. The issues you are describing sound pad related not rotor related. You are trying to say that a 299x32mm rotor has less heat capacity compared to a 299x24mm rotor with less veins. You should definitely not be replacing rotors just because you see some micro cracks on the surface. I do agree that a "float on rotor" design instead of "float on hat" would be better though, but might not be possible with this caliper and rotor size.

decepticondc5

I think you are looking at this on a bit too small of a time scale. Per one corner/braking event, sure, its very likely there is little to no thermal benefit from the urge setup... The OEM setup has no problems with a single braking event either. Problems arise when you are asking the brakes to take the abuse lap after lap after lap and this is where a BBK comes into play. I think the only real conclusion that can be drawn here are that the DTC-30 is just the wrong pad for this application. When you run a pad that is operating outside of its heat range its causes you to stay on the brakes for longer periods of time and that is the real killer here.

Urge

We appreciate the feedback of our kit.

We did spec this kit to reduce weight and improve cooling. As you noted the thermal mass is about the same as OEM. Removing the hub mass from each rotor, our disc has about 10% more thermal mass at the edge of the rotor where it counts the most. Additionally, the 60% larger vane width, >2X increase in number of vanes and directional vanes keep the brakes running significantly cooler than OEM. Any thermal test will prove this.

Having a larger thermal mass simply means you have a larger heat capacitor, so it just means it will take a little longer to fill up, but if it does not dissipate heat quickly, then having a larger thermal mass delays the inevitable. We feel our rotors will dissipate heat significantly quicker than OEM and quicker than non AP comparable kits.

We specifically choose not to offer the 325x32mm AP rotor as they added 5 lbs of rotational mass per corner and felt they were overkill for the S2000 application. Using rotational momentum estimations, it is like adding 30-40 lbs of static weight to the car.

After selling 60+ sets with >25% being high horsepower boosted cars or dedicated track cars, we have not had one claim of our rotors being under sized until now. We have had another vendor and several customers who have not had personal experience with our kit ask for bigger rotors based upon theory. Again, they have not tried our kit personally. As far as the short track racing, it is by far the most abusive brake environment possible as the cars are applying full braking force ever few seconds 4 times per lap. Watch, any NASCAR short track race and they run maximum ducting at those tracks and longer tracks they tend to use the least amount of braking even though the speeds are much higher as Aero drag helps quite a bit.

That being said, your personal feedback is important to us and something we want to investigate earlier. I went back and check our email conversations and you never mentioned felt the kit was undersized or mentioned early cracking. You did mention the clicking and we asked to try a few things. We followed up 3 times after some back and forth and did not hear from you again. I agree with other feedback on this thread. I think there is an opportunity to try a different pad or add ducting. Maybe remove the dust shields if you have not already.

Adding a much larger rotor has downsides to costing and weight and we felt those compromises are not worth it and stand by that decision based dozens of customer emails and 8 S2KI reviews on our site. Additionally, we have sold less replacement rotors than kits over a 5 year span implying the rotors are lasting quite a bit. We also have direct feedback from several track focused customers that our kit has lasted tens of track days and many more sessions before needing replacement.

We would be willing to work out an offer on other pads, new rotors and cooling suggestions to keep your weight down and fix the issue you are having. Please contact us at your convenience.

DefSport

maybe they are worse than the pics show, but looking again, they really don't look bad to me.

As for Hawk pads being a problem, total crap. Those rotors would have been fine with DTC-60s. The 30s are marginal on the front of anything.

With a lightweight rotor you are absolutely forced to a higher temp range pad. And yes, I would agree you probably have the same or slightly higher peak rotor temps in braking zones as a stock rotor due to a similar thermal mass. Which makes perfect sense on why you need a similar pad. I think you'll get a tad more life out of these rotors than stock, but not a substantial amount more.

if you want to try to run a more street based pad, you'll need a much larger and somewhat heavier rotor.

gptoyz

Take a look at this graph.

The DTC-60 has about 30% more mU or cF than the DTC30. The DTC 30 is by no means sufficient for track duty.

The temperature it can hold at maximum braking torque would have probably melted the DTC30 - that's really where you will destroy the inferior pad.

Btw, what pad were you using in the rear?

If you compare your bbk with your oem setup using the same pad, you should get significantly more life out of the front pad. The rears being not vented and also a slider will probably continue to wear at the same rate.

What you will gain vs the stock brake setup are:
- less unsprung mass (in theory better handling, better acceleration, better handling)
- quicker heat dissipation - larger pad
- boil less brake fluid
- less rotor drag, since the rotor will be allowed to float between the pads

I'm sitting about a low 2:01 on my stock CR with DTC60s and rs3v2s. The 60s will probably your raw time as you spend less time slowing the car down.

Bullwings

I agree with others in echoing that your selected pad was not up to snuff.

People have used the ST40 328x28 kit with the provided pads and had problems at the track due to the pad not being able to handle heavier track use. A change in compound completely fixes that. Stick with a DTC 60/70 or equivalent for the front - it's what i used with my ST-bbk.

gtracer

DTC pads are horrible in my opinion. Little to no modulation and very harsh on discs. They would also leave loads of deposits and often cause vibrations.

I would strongly suggest running some ducts for cooling and Pagid RS19 or 29. I think they came out with a new compound that is even better than the 19/29. RS 44 i believe!

DavidNJ

First, I thought you did a good explanation between thermal capacitance and cooling. They reach an equilibrium but there is massive heating and cooling; IzzyRacing has added a brake rotor temp sensor. Their video (in an S2000) around VIR should really make it clear: The fade is all in the pad.


That said, you have the wrong pads. Maybe, just maybe, a DTC30 would work on the rear. 130hp Spec Miata's run it on the rear, but they do that to reduce rear braking relative to the DTC-60s they run on the front. Those pads are done by 900F and your fronts are probably way hotter than that. 900F is less than 500C in the video.

I think the DTC50s, if they are available, are maybe the best choice in the Hawk lineup. However, they aren't available for every caliper. They are less temperature sensitive than the DTC-60 with a higher coefficient. If you need the extra 100F or so a DTC-60 provides there are other problems. This is Hawk's writeup on the DTC-50: "The DTC 50 has tremendous stopping power with an industry leading initial bite. It also has a very predictable Mu gain throughout the torque curve, providing the purest of drivers the most desirable pedal feel on the track."

Which brings us to rotors. there are lots of 11.75x32 rotors out there for AP floating mounts. It is the standard size for 500hp, 3000lb super late models on asphalt. I have one...with AP calipers. AP has a 28 vane and 60 vane for stock cars. The CP3862 is the 60-vane rotor. It should have more than enough thermal capacity.

Net: change the pads and if you don't have them, add cooling ducts.

imstimpy

As many have experienced, you and myself included, a big brake kit does not mean you can now get away with running street pads at the track. I ran Carbotech XP10s on my SoS rotors and I run XP10s on my StopTechs. What you are seeing, as was already said, is a pad operating outside the thermal range. A fade, in this case, likely has far more to do with the pad going beyond its operating temp and far less to do with the thermal capacity of the BBK. Think of it this way: the pads have to stop the car no matter an OEM rotor or a BBK rotor; the pads still have to convert the same energy into friction and heat regardless. The advantage of the BBK is to act as a larger heatsink, providing better thermal stability to draw the heat away from the pads and to avoid contributing to the pad temperature.

To me, your rotors look like what I call "pad smearing" and it cleans up with some driving on the street or track braking within pad operating temperature. If you are really concerned about the rotors, get some thermal paint and find out just how hot they are getting. I wouldn't be, though, I'd switch to an appropriate track pad and enjoy.



I have not used any Hawk pads besides the HP+ for autocross. I feel I have found the sweet spot with the car's power, weight, 255 street tires, and the brakes' thermal capacity with the Carbotech XP10s or the Cobalt XR2s. Anything more aggressive and modulation suffers; anything less aggressive and pad longevity suffers.

decepticondc5

a little off topic but what is up with that massive amount of counterweight on the wheel?