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Discussion Starter · #1 ·
This report is a continuation from my original report posted here:

http://www.stingrayforums.com/forum...-track-day-new-c7-report.html?highlight=track

This is the second track day in my car.

What I've done to the car since the first track day:

Replaced brake fluid with ATE Super Blue. Completed a performance/track alignment. That's pretty much it.

The track is Buttonwillow Raceway. Fairly flat and a bit bumpy, but has some really cool, fast sections. The first part of the track is fairly tight, which accentuates any push tendencies a car may have. The back half of the track is fast and flowing. Quite fun with lots of run-off.

Weather was high 60s in the a.m., getting up to mid 80's later in the day.

I set cold pressures at 27 lbs vs 26 lbs since I had a bit of rollover the last time. Pressures ended up around 33 lbs hot and rollover wasn't quite a prevalent.

I enjoyed the car as much as the first day if not a bit more. I felt more comfortable allowing the car to slide a bit on some of the high-speed sections and it was very predictable each time. As mentioned before, the stock tires are about the best I've driven on a track. They have a good amount of grip for the first 4-5 laps. As any street tire, the tend to get greasy when hot and will start to go away. They do this very predictably, however; and never sneak up on you.

The acceleration off the tight corners is very good. The eLSD does an amazing job of allowing you to feed in throttle while maintaining grip. Obviously, getting too greedy will result in the rear breaking traction, but if you finesse the throttle; it gets off the corner really well. Turn-in on the tight stuff illicited some understeer. It became more pronounced later in the day as the track heated up and the tires got hot.
Turn-in on the faster corners allows for some rear rotation that can be managed by picking up the throttle slowly. You can essentially toss the car in and throttle it in order to set the nose where you want it to be. VERY fun!
The car makes it very easy to get a good laptime, especially if you are smooth with inputs. The Vette does require a bit of patience to let the chassis "take a set" before major inputs. This is a bit different than the Porsche which allowed more of a flick. But, if patient, the Vette handles very, very well.

I ran every session in Track mode and manually turned ALL electronic aids off. I do this by holding the TC off button down until both the TC off light and Stabilitrak off light come on.

I checked the oil level 5-8 minutes after each session and never had to adjust the oil level as it was spot on.

The bad news: I wish I had none to report, but the brakes on the car just seem to struggle to provide on-track performance. Even with the Carbotech Race pads and high-temp fluid, plus those pesky rotor cooling rings. I'd still get brake fade before the end of each session. Fortunately, after cooling off; the brakes would come back for the next session. At a fast track pace, the brakes have trouble dealing with the addtional heat generated. I had hoped that the Z51 track package with the upgraded brakes would truly be track capable, but I am beginning to think that my first "it's too good to be true" reaction may be reality.
I'm going to try Castrol SRF and steel-braided lines before my next day at the track in hopes that maybe this will solve it. I am optimistic, but also realstic. If it doens't do the trick, a big brake kit may need to be an investment I make in order to continue enjoying track days in the car.

BUT, I don't want that issue to take away from all of the goodness of this car. It is simply amazing how capable the handling and power are on track. It brings a huge grin to my face every corner and every acceleration.
I can't wait until May 2nd to do it again!

Mike
 

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Nice write up. I've raced at Buttenwillow many times and could visualize your discription of your laps. It's disappointing that the brakes seem not up to the task. I would think the Z51 could for sure. I wonder what the showroom stock drivers do.
 
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Nice review. If the car is almost up to Racerbob's standards, it sounds like it will blow my expectations away!
 

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Any idea on rotor temps coming off the track after noticing the brake fade? That might help us track down the weak point in the system.
 

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Yeah, I'm wondering if the brakes themselves are indeed being mechanically overworked vs. an issue with the fluid/lines. In other words, if 3300 lbs + driver repeatedly stopping after a 460hp acceleration is creating more energy than the brake rotors and pads can dissipate through heat. With the enlarged brakes on the Z-51, you'd hope this wouldn't happen.

Also, a 12/10 combo on the Carbotechs sounds like something I'd use on the S2000. Maybe the weight and horsepower of the Vette need a stronger combo, like 20/12, if you are going fast enough? That'll get you another 150F buffer on the front pads according to their specs.

If you can, at the next day you do, borrow a non contact IR thermometer from someone in the paddock and get the rotor temps (or buy a cheap one from Harbor Freight, you can also use this for your tire temps).
 

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Discussion Starter · #8 ·
FormulaRedline- Yes, the thermometer is a great suggestion and I used to have one in the toolbox.
I've had no previous experience with the Carbotechs and went with the vendors recomendation for the car. Very well could be the wrong compound. So many variables......
 

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Yes, for sure. Hard to know before you try them. The vendor may have also thought you were going for a typical track day, but maybe you were driving at a bit of a higher level if you already knew the course? The pads I could get away with on a random DE day and the pads I need when doing a Time Trial at my home track are probably different. I really only use one type of pad but I certainly wear them at different rates depending on the event.
 

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Discussion Starter · #10 ·
Just spoke to Adam at Amp'd Motorsport (Carbotech vendor). He's a good guy and willing to swap the pads if that is what I truly believe to be the issue. He feels that the XP12 should be more than adequate especially given its ability to handle up to 2000 degrees. I keep coming back to those pesky cooling rings and wondering if they truly help or hurt. Maybe they dissipate heat towards the brake lines and fluid?
 

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I just did a very quick search, so it would probably be good for you to look a little more in depth, but I found C6 Z06 owners, which I would expect to have similar characteristics/requirements, split between using XP16 (replaced by the XP20) and XP12. The racers were more likely to be using the XP16...so that might be it, but I wasn't really seeing any complaints per say on the XP12, so it might not be.
 

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Discussion Starter · #12 ·
I think in order to attempt to pinpoint the issue, I'll run the SRF fluid and make no other changes. Well...not true- I am also adding the steel braided lines.
 

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I can''t imagine ATE Super Blue wasn't doing the job (but who knows). It will be interesting to see if the lines make a difference.
 

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I think in order to attempt to pinpoint the issue, I'll run the SRF fluid and make no other changes. Well...not true- I am also adding the steel braided lines.

Where can I get SS brake lines? I cant find them any where for a 2014 Corvette
 

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Any body able to figure out how much brake fluid is needed when switching to DOT 4?
 

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I install SS braided lines on all my track cars before I even attempt running them. I have seen too many cars lose their brakes for this very reason. SRF is a good choice. I would have assumed that with the Z51 package the brake lines would have been installed at BG. What are they thinking? There is no mention of them on the ZO7 either, so that is troubling.
 

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Any body able to figure out how much brake fluid is needed when switching to DOT 4?
When I look ad my receipt for have my dealer switch to DOT 4, is says quantity "8". I'm just not sure if it's litres, quarts or what. The unit price was $5.95.
I don't use the cooling rings on track, I haven't experienced brake fad yet this year with the stock set up. Maybe the two tracks I've been on haven't been big and fast enough? Next year I'll be trailering it to Calabiggie next year. That's the best track we have in Ontario. That'll test the car and me.
I also would lower the air pressure after the first session back down to 26psi. It made tires feel less greasy for the second sessions. When I checked the edge of the tread the wear had not gone past it. So I felt I was rolling the tire just enough.
Call me naive, but I just wonder how Spring Mountain can run all it's cars stock and have no issues. I would think if there were any issues with the car, they would upgrade everything so they wouldn't get sued when a student blows through a braking zone.
 

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Stainless steel brake lines anyone?
 

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Stainless steel brake lines anyone?
Get Goodridge SS brake line kit and change fluid to Castrol SRF. If you plan on tracking the car regularly then the fluid should be changed at least annually. BTW don't keep opened bottles, brake fluid deteriorates rapidly when exposed to air.
 

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An option to help shed some heat that we have used on our purpose built track cars is from Kluhsman Racing. KRC Racing then go to "products" then "KRC full parts list" then to "custom" and scroll down until you see the brake pad insulators. Not sure if they have them pre-made for C7 yet but they can make them in house. It is space shuttle nose cone material. Works really well. The hotter the brakes get, the better it works. It's pretty bizarre but we found it really worked.
 
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