Fatman0203

No thats exactly what he's getting now. Fender well liners, thanks now I know their name.

maxcooper

Fender well liners line the fender around the wheel. Brake ducts deliver air to the center of the rotor. Just making sure the terminology is clear.

-Max

Fatman0203

Yes yes, he has no ducts, he is going to get some and he will be going to Roebling in the end of may like the 29th lets see how they hold up there. Is that track harsh on brakes? From what I understand Sebring is really tough on brakes and could be a reason why.

skunks

make sure the brake ducts he has will deliver most of the air to only the eye of his rotors, if not (like the cwc ones) it may make the problem even worst (the cwc ones blow air across the entire face of the inside rotor only and this would cause more warped rotors/cracks)

GarySheehan

I have used the Stoptech brakes on our 2002 Subaru WRX USTCC race car for the past 2 years. I have never experienced a rotor issue like this. I usually get through 4 full race weekends before I start getting significant heat checks in the rotor face. Never had a crack that goes to the inside of the rotor.

I can't figure out what's going on here. Even with extreme heat, I would think you'd be getting significant face cracking, not a single big crack.

Gary
Sheehan Motor Racing
www.teamSMR.com

tims

Gary,
Maybe you could give us an idea of the setup you use and maybe the pad material. it may help him understand what it takes in terms of car prep to make the brakes last.

Fatman0203

Well I looked at his rotors closely and they were mostly stress cracks except some cracks that went directly to the (allen?) bolts in the back. None the less Stoptech has been completly helpful about it.

artowar

iTrader: (1)

How about those pictures?

jhillyer

We see cracking from a couple major problems. Rotor expansion pulling against rotor mounts, and rotor expansion pulling against the shape of itself. Plane areas of the rotor like to crack radially, and any slots or cracks are relief of stress in their areas, but slots and holes can guide tension and crack along these altered surfaces. I'm surprised the road racing market continues into single-rotor, single-caliper designs, and does not borrow from offroad and biking with ultra thin sliced-up discs, multiple discs, and sometimes two separate calipers sharing the same brake rotor. I can't think through any cast chunk performing as well as a wafer. Someone help me.

maxcooper

F1 cars from the past had two calipers on one rotor. It seems one rotor and caliper is a more efficient design from a mass standpoint, so as long as you can get away with it, it seems 1/1 is the best way to go.

Fade resistance is largely a factor of how much heat the braking system can absorb or reject, so we see vented rotors (to aid heat rejection) on high performance and race cars.

Cars weigh a lot more than bikes, so I don't think thin, sliced up rotors would survive on a car, generally speaking.

-Max

Travis R

I'd be surprised if your friend was getting the bearing flex that you described earlier. It is my understanding that modern Subarus have pretty wide bearing spacings so they take the loads really well... something they learned from years of WRC. The wide bearing spacing is one of the reasons Subarus have wheels with really high offsets (52mm).
Try more ducting.
Good luck.

Silkworm

Again, heat absorbtion and dissipation. The heat generated slowing a motorcycle is a fraction of the heat generated by a 2600lb car. Compounding on that, cars generally do not have anywhere near the amount of airflow that a motorcycle has around their brakes.

So you build more heat, and you disperse it slower, than a motorcycle. So you build thicker rotors, out of different materials, to absorb that heat until you can disperse during the periods you have where you're not under braking.

Again, not a brake expert, but that's my .02$

Silkworm

Hey Gary, good to have you on the board

Paul Cabana
#33 PS-1
Head-On Photos

rx7tt95

Fatman,
What events does your buddy track at? NASA? Chin? Just curious as I attend most of those events. It isn't silver by any chance? There were a number of cars at the last PDC/NASA event at Sebring on Saturday. Nick (N-Tech) sells plenty of Stoptech stuff for 350Z's and a few of his students are using them without issue as he is himself. And the Z is substantially heavier. I'd definitely lean towards brake ducting as being the issue. I'm sure you're using a good fluid like Motul or Pagid, right?

Fatman0203

Your on the money, but he installed some brake ducts and they seem to be working. He understands that after a few events you get stress cracks and will have to replace them, but either way not after one event. But now they seem to be holding up real good and he is pretty quick with the minor mods done to his car. I think I timed him at a fastest of 2:45:04. What car you got? Nick is here in Florida? I want to look at the N-Tech brake in person for the FD before I decide to buy.

rx7tt95

Yes, Nick is located in Winterhaven. He has a car in the shop right now getting a complete track-only conversion along with the Stoptech front brakes and 99-spec rears. His boosted, fully built engine 350Z has the stoptech kit as well. One of the guys at Saturday's event (350Z) had the 4 wheel 350Z Stoptech kit.

I've stopped tracking as I'm the "official" photographer for NASA. I have a black RX7 with the bronze Volk rims. At Sebring I had my VehiCross and not the 7. Check out the attached pic. Is this him? He was running her pretty darn hard. Notice the RX8 in the background

rx7tt95

Pic didn't post...one more try here

Fatman0203

I saw the 350z with the 4 wheel stoptech kit but honestly, I think either the car needs to go on a diet to be competive in track. I just dont see where the Hell 3300 lbs are in that car.

My friend always drives hard, since the car is rarely his daily anymore it doesnt matter, thus why he beats that crap out of it. He is pretty tough on the brakes too. This weekend he was using the Kuhmos I think but he said he didnt like them, said they were too slippery.

Hey you going to Homestead on June 12? I'll probably see you there if you go.

95MX6

I know he's kinda solved this with the ducting, but when I read about it cracking from the bolts I though is he properly tightening his lug nuts. If he isn't using a good tightening pattern and a torque wrench the rotor could be under a lot more stress than it should be and thus failing at high temps. Even in nonracing conditions a rotor can be warped or cracked in this manner. Of course I doubt this is the reason since he seems to be "in the know".

rx7tt95

Hrm...didn't think of that one MX6...good call! Yes, I'll be there on the 12th. Tried to post a pic but the forum isn't letting me. Imagine that. Microsoft servers suck! Maybe someone else will have better luck? If you have a server, send your e-mail to me and I'll forward the Scooby pic w/the RX8 (rotary content) in the background.

Fatman0203

Can you torque something that requires allen bolts?

Fatman0203

www.freepichosting.com

let me know if that works.

95MX6

Yes there are socketed allen tools that allow for much more torque than the normal allen wrench using normal ratchets and breaker bars, a few weeks ago I was using an allen tool with a 3/8" breaker bar and had to have been applying at least 120 ft/lbs to get a stubborn allen bolt lose.

Fatman0203

Interesting, hmm when I do my brakes, I'll probably need it, and hint my dad into getting a new tool. w00t!