madcorgi

I continue to have big problems with the brakes on my 07 Z51 at the track. Yesterday at the Ridge, in Shelton, WA, the car lost its brakes (as in pedal to the floor) after just few a laps. The rotors and pads were (Hawk DT70s) new, as was the fluid--Motul 600. I also added Z06 brake cooling ducts since the last time I ran the car.

I'm baffled--this is the second time I have lost the brakes at this track. I have run at Pacific Raceways, which is far harder on brakes, without problems. The difference was the pads-- I used Hawk HT 10s, which are a lot softer, and which went metal to metal after the 8 sessions my son and I ran.

A couple of other Corvette guys told me the stock brakes are simply not up to the task of road racing, and recommended Stoptechs. The problem with Stoptechs would require new wheels, since the bigger calipes will not clear the stock wheels.

Anyone have a lower budget suggestion?

Terry

Gearhead Jim

Someone once said:
"People keep fixing their Corvette until it's broken."

I did about a half-dozen track weekends at places like Mid Ohio, Road America and Blackhawk Farms; with totally stock brakes on our C5. Yes, I started every weekend with new pads and good rotors, fresh Ford brake fluid. And yes, the pads were nearly worn out by the time I drove home. But I never had any serious issues with brake performance out on the track.

After the dangerous problems you've had, I'd be tempted to go back to totally stock except for Ford fluid, set a mental speed limit for the long straights so you're not heating the brakes too much, and slowly work up from there. Hopefully, you have the original parts and wouldn't need to spend a lot of money.

You can only be lucky so many times...

RicK T

In addition to waiting for help here, you might also ask in the AutoX/Roadracing Forum where the guys who do that kind of racing all the time hang out. I bet you'll get some good help there. Hope you get it figured out and can have some fun with the car. Good luck.

http://forums.corvetteforum.com/auto...roadracing-23/

oldmansan

Even the Z06 brakes don't fare well at the track. Look at the video where Aaron from PFADT took their new Z06 to the track for it's maiden voyage. The brakes didn't last one session. One of the bolts literally snapped.

I got rid of the stock brakes fairly quickly. IMHO they are not even up to spirited canyon carving. For what it's worth I thought my Lotus Exige's brakes were weak too. Stoptechs on the Corvette. AP Racing on the Exige.




San

HeavyRightFooT

I have never ran the ridge before installing my stoptechs (which I love I gotta say) but ran PIR many times on stock calipers with aftermarket brake lines, carbotech pads and motul rbf600 or ATE super blue liquid and DRM cooling ducts, and never had much of a problem apart the speed at which I was going through both pads and rotors... and PIR will beat on your brakes.

Only thing that comes to mind would be maybe the matching of your pads and rotors, proper bedding of the pads and/to rotors, and maybe you are dragging your brakes too much ? do you have good aftermarket braided brake lines ?

V4kerker

madcorgi do you just have the brake ducts or hoses and spindle ducts also? I have a 07 C6 base that I put brake ducts,hoses and spindle ducts on and been trouble free. I'm running street tires and hawk HP+ pads and stock pads and Valvoline syn 3/4 fluid.

X25

Since installing ducting did not change anything, I'm wondering if it's the rears causing you trouble. Are you running full stability control on? If so, you should switch to either Competitive (which still uses brakes, but less) or off. Stability control uses quite a bit of rear brakes, and perhaps your rears are the ones causing the boil and the eventual fade.

I ran the same track, Ridge Motorsports park with stock Z51 calipers and ST43 pads on blank rotors in my brother's 2008 C6 Z51; had no issues with brakes whatsoever. There are many corners at this track back to back; I'm sure stability control would go nuts if it's enabled.

I think the track that is most demanding on the brakes in our region is Oregon Raceway Park. Even there, the stock brakes with good pads held up nicely. I drove with my '06 Z06 and '12 Grand Sport there as well with no issues.

In my opinion, GS/Z06 calipers are very adequate especially if you don't have competition tires. Z51 is pushing it a bit, but again, with no competition tires or 100+ HP from stock, I think they are still adequate, at least in our local tracks.

The biggest problem with GS/Z06 calipers, again in my opinion, is how low thickness specs of the brakes pads are. Once they go below a certain thickness, they will start transmitting the rotor heat to the calipers, and you know the rest

timd38

I am by no means a brake expert, but nothing in your brake system has really changed. I don't believe that pads and rotors will cause your pedal to go to the floor and the brake ducts also would have no effect.

You may have an issue with master cylinder.

I, like oldmansan, got rid of the stock brakes and replaced them with Wilwoods, using the stock master with no issues. I go to Road America and they have two real long straights and the cars stops fine. Just keep in mind that the older I get the faster I was.....

taken19

I would guess that it's either the nannies being active too much on the track or one corner hanging up. Have you greased the pins recently or inspected the pistons?

Other options include the master as stated before or ABS modul,e which would inform you on the DIC.

Pull each corner and inspect for obvious signs of overheating on the pads, rotor, etc.

oldmansan

Good point about the nannies using more rear brake in normal mode.

San

madcorgi

I run with the nannies off. The Ridge makes the car undriveable with them on, IMO, because of all the elevation changes. They come on a Pacific too, the way I drive turns 3B and 6, so I turn them off there.

I thought about the master cylinder, and will replace it when I go to bigger brakes, but much more is going on.

Here's an interesting theory: when my son and I ran Pacific, we ran fairly soft Hawk HT 10s and had no problems, other than the fact that they were all used up after one day. Since then, I have used much higher temp, more aggressive pads, like Hawk DT 70s. I wonder if the softer pads became the sacrificial part of the system, such that the heat was dissipated as they wore away, instead of transferred the calipers and fluid? The more aggressive ( i.e., high heat) pads have not worn past about 70%, even with the brake fade, but they have gotten white hot on the backing plates and toasted the rest of the system, causing me to think that they are transferring heat right through to the rest of the system. In fact, the fromt calipers got so hot that they burned the cheesy rattle-can paint off the front rotors, so now they are the correct gray color again. The rears are still yellow, so I don't think the problem is rear brake induced

I also experienced intermittent nanny interference during the problems. I think the is some sort of sensor that switches all the nannies back on when it senses low brake line pressure, despite the fact you have turned them off.

Another fun fact. The front rotors are identical, so the vanes on the right side actually run backwards. And, sure enough, it's the right side that was getting the brunt of the beating, with the rotors becoming deeply scored.

I'm bummed that none of the aftermarket brake kits I've found won't clear the stock wheels, as I really like them.

Terry

oldmansan

Not a fan of cast wheels for the track. I run forged wheels. I went 5 sizes larger front and rear and still saved weight over the stock setup.

San

taken19

I hear that Wilwood brakes will clear the stock wheels with a 1/4' or 3/8' spacer.

timd38

I have a set of 2009 wheels and Wilwoods brakes and I only have a 1/4" spacer on the front. I don't think you need longer studs if you only use a 1/4" spacer. I have long ARP studs, so I can tun over 1/2" spacer if I want.

I went with Wilwood for a couple reasons. Good reputation, lots of product choices, great customer service, and they fit stock wheels.

Did I mention that the work really good too.

madcorgi

I thought the stock wheels were forged Speedlines.

X25

Indeed as far as I know, the OEM wheels are very light for their price. I have a second set of wheels for track use, and I still bought OEM wheels since they are the best bang for the buck.

madcorgi

Which Wilwoods did you get? The ones they recommended to me are the W6AR/ST kit.

Terry

Gering

Nice Looking Lotus!!!

JCtx

While on that subject, even Ferrari owners say their Brembo carbon-ceramic brakes are crap on the track. For serious track duty, no stock brakes are satisfactory. And it's the same with tires, suspension, etc.

madcorgi

Very true.