jls288gto

Ok, this was my first HPDE with the Vette, heres the story:
VIR full course, temp today of about low 70's. I was running 2:20 laps and getting brake fade by the 6th lap. Braking on the backstraight at about the 3, and at the 5 on the front. I am a little frustrated that the brakes were fading. Here is what the car has done to it.

07 C6 with Z51, DBA 2pc front rotors, stock Z51 rear rotors. Hawk DTC-70 front, 60 rear pads, ATE superblue fluid (freshly bled at the track), foglights cutout for 3" ducts to front spindles. The engine is stock, running stock wheels with Toyo R888s with multiple events on them.

I know that in hotter weather it will only happen quicker, and I thought the foglight ducts would stop any fade from the posts by people who have done it. Any input on helping stop any fade would be great!

stevensa

You have all of the Active Handling and Traction Control turned off right?

RX-Ben

You could always spend a few more bucks and get RBF600 brake fluid, which is a bit better than the ATE, though I don't think anything will save you if the nannies are pretty active.

PaConehead

You didn't mention brake lines among your mods, if you're still on OEM rubber lines, that could be the source of your fade.

MJM

Something is wrong.

With those lap times, ambient temps, and high-temp brake fluid you should be good to go.

jls288gto

had the competition mode on.

good thought, still factory lines...

Just for curiosity, what is a good lap time at VIR for a basically stock C6 non-Z06?

stevensa

Comp mode is most likely causing your issues, dragging the brakes all over the place.

RX-Ben

I think Travis has the TTA record with a 2:04.6, in a C5Z. That would be stock engine and some form of smaller grippy tires, depending on how he spent his points.
A C6Z with R comps and good pads could be a bit faster.

jls288gto

Ok, but non-C6 Z06?

RX-Ben

Opps, well, you have the same hp, You probably have another 100lbs, maybe. So, a good time would be in the 2:10 range.

Bill Dearborn

Define what you mean by brake fade? Did it take more effort to stop the car as the brakes heated while the pedal was firm, or did you have a long pedal and had to pump the brakes to get the pedal up, or did you have a spongy brake pedal? The solution for each of those could be different. Since you have a C6 Z51 your brakes are susceptible to the same pad taper issues that occurred on the C5s. Inspect your front brake pads and see if they are tapered along the length of the pads. Pad taper can cause a very long brake pedal where the pedal sometimes will drop very low upon first application. A quick double pump will bring it up where it will be firm for that application. One way of doing that is to use your left foot to tap the brake a couple of times while heading down the straight. Same thing can happen if you have a wheel bearing that is loose since that can cause brake piston knock back.

If the pads overheat you usually have a hard brake pedal but the car doesn't stop well. If you boil the brake fluid you will have a spongy pedal (different than a long pedal) that may take a double pump to get sufficient pressure on the pads. The difference between 70 degrees and 100 degrees ambient temps has little to do with brake issues as that 30 degrees is nothing compared to the 1600 degrees you may be generating when stopping.

Also, your issue could be with the rear brakes Vs the fronts so you need to focus on both ends of the car.


Bill

travisnd

A good time for a stockish LS2 C6 on stickey street tires is in the 2:10 range. I recently set the TTA record with a 2:04.6, but my car is gutted and running on 255/35/18 Hoosier A6s. The engine is stock and the suspension is stock other than Pfadt poly bushings and T1 swaybars.

For brakes I'm running DBA 2-piece rotors up front (love them), Stoptech SS brake lines, Carbotech XP12/XP10s, and ATE superblue all with DRM duct extensions and ECS spindle ducts.

I've never had any issues with brake fade. I fight taper by lubing my caliper slide pins before each track weekend and flipping my pads side to side after each day.

You'll need to provide more detail as Bill mentioned for us to better help you. I highly doubt it's brake fade running the components you are and turning 2:20s. If you have comp mode on AH is probably coming on more than you realize and working the rear brakes. My dad used to go through a set of rear pads in one weekend w/ comp mode on in his old '04 Z06. Once he turned it off that stopped for good.

jls288gto

The pedal would go down, then i would pump it and it would still drop down significantly, but firm up more.... does that make sense?

travisnd

Fade is when the pedal is firm but the car isn't stopping. The pads are overheated and the friction produced goes way down.

Sounds like air in the system. I'd check everything over re-bleed and re-lube the slide pins. Even when my brake pads are near the end of their life my pedal is still firm and no need to pump the brakes up.

jls288gto

10-4....

looks like I'll put stainless lines on, check pads for tapering and lube the slide pins. Then disarm the competition mode and try that on the next VIR day.

Appreciate all the info!

AU N EGL

brake fluid is boiled. Need to do a full flush of the brake fluid. ATE is great brake fluid, but needs tobe flushed each day on the track.

Do not worry about lap times. Just be smooth as you can be.

In sort notice you be in the low 2:10s

travisnd

That's a bit extreme to me... no need to flush between each day at the track. At most a few pumps at each caliper if any. I've never boiled ATE superblue and I don't bleed the brakes after a day on track if they still feel fine. I bleed them as part of my prep before the weekend.

trapp

Consider Titanium shields for the brake pads....(at least for the fronts) it really helps keep the heat from the calipers and fluid...I noticed a difference immediately.

tispeed.com

travisnd

Yes... I run these as well. They're fantastic and they'll also keep the rubber piston boots from melting

John Shiels

take fluid out of the equation and use SRF. Your stock lines in good condition are not giving you fade. You bleed some of your fluid but how old is it?