AlphaKing

I plan to attend a few HPDE weekends this summer. I am looking to buy DBA rotors and Carbotech pads just for track use and maintain the stock rotors and pads for street use. Those selections were made based on research and first hand feedback.

I found a seemingly good deal on DBA 4000 series T3 Clubspec rotors. My question is: should I get front and rear rotors, or can I run a more aggressive pad on the rear with the stock rotors on the track and still have decent rear performance while maintaining the life of the stock rotor relatively well? Trying to justify spending another $400 dollars on rear rotors if the stock ones will be sufficient.

Chance575

stock blanks and good pads

AzDave47

I have been running the stock rear rotors with Carbotech Bobcat pads for the street and Carbotech XP 10's for the track and these seem to work fine. These are the original factory rear rotors and previously used the OEM pads.

I use a new set of factory rotors and the Bobcat pads for the street. The OEM rotors and pads worked OK on the track but didn't have the stopping power I was used to from track pads. As soon as I went to track pads I started to get brake fade, fluid boiling and other problems.

Now I run dedicated front track rotors (AFX two-piece rotors with the HD iron rings), Motul RBF 600 brake fluid, and 4" cooling ducts from the front grill into modified factory plastic duct, and 3" ducts fromt the outlet to the rotors and have solved the track cooling problem. I run Cobalt XR2 front track pads.

I have over 40 years of competition track driving and instruct at HPDE's.

Bill Dearborn

Up until I converted over to a Wilwood BBK with two piece rotors the best rotors that I found for the C6Z were the stock front rotors. They would take 5 days of track abuse all for $100 shipped to the house. From my experience the best rear rotor is either the Coleman two piece or the Wilwood two piece. The stock rears would crack after 5 days as well although they never heat checked they just cracked. I actually wore out the Coleman rear slotted rotors. Wore them down till the slots were no longer visible. Looks like the Wilwood rears will do the same.


Bill

philpacs

I suppose it depends how hard you are on the brakes and if that track is hard on them etc. For most people I bet you'll be fine with stock rears rotors with same front pads. As I have found in South Florida tracks, with the heat the stock caliper set up even with a brake cooling kit, AFX rotors, SRF fluid, cobalt, DTC-70 or carbo pads, SS lines etc still cannot dissipate enough heat and I can only get about 3-4 hot laps before they get too hot. I then have to do an extra cool down lap then they still almost melt to the pads(It's hard to push in neutral, piston sticks) etc. My experience with stock rotors is I get one maybe two days before they warp. Still fun but if I had to do it over I'd do a BBK and save the hassle. I've had about 45 track days at one track to really try different set ups.

Bill Dearborn

Warping is just uneven pad deposits which can happen at almost any time with any rotor. They can even smooth out during a session if you keep running the car hard. Cracking means you stop driving.

Bill

AzDave47

Doing Jim Dillon's 4" front cooling ducting took care of my front brake overheating problem. It cost me about $70 in parts and half a day to do the install.

See this link: https://www.corvetteforum.com/forums...-new-look.html

Many may not need this if they are not doing intermediate or above driver groups.

Beast5spdGTA

FWIW, I cracked a brand new stock replacement rotor in 70 track miles, XP24s, rears were XP8s. I also cracked 3 other rotors that weekend at Sebring. The others were (2) DBA single piece after 6-8 days IIRC and one was a used AFX ring with unknown track days (less than a day by me and a friend), but I know it had been cut down before.

AFX 2 pc with HD rings is appearing to work the best so far. Using XP16s currently. Previously had XP10s, XP24s and will go back to XP24s after the XP16s wearout.

I run generally a best of high 2:20s at Sebring with a passenger. Full weight street car with pads, DOT slicks and brake cooling ducts and aftermarket oil cooler. Boiling fluid is pretty common unfortunately. Motul 600 now, ATE was even easier to boil.

AzDave47

Do the cooling in the post above!

ckchan10

That is EXACTLY what I've been looking for! I've been having brake overheating/cracking issues for quite sometime and have been trying to think of a good fix (I run stock brakes with the Quantum ducts). Since this isn't a prefabricated kit, what parts are needed and where did you buy them?

Thanks!
-Danny

AzDave47

PM me your normal e-mail address and I'll send you detailed info, pictures (I don't use a service so don't post pictures here) and a parts list. If you decide to do it, I can give you tips over the phone. Unless you have slim arms (I do), the front fascia may have to come off. I was able to do it without that chore.

I use the quantum ducts, but made a modification the the factory duct outlet to increase it to the full 3" quantum hose size.

As the earlier post indicated, Jim Dillon from FL did it, posted here and helped me out a lot, so always kudos to Jim. Fortunately his new C7 Z06 comes from the factory with the front duct inlets.

Dave

80atez

I think I'll be doing this mod this winter.. Thanks.

I have added SS brake pistons for heat transfer.

I use Xp8 rear, front are carbotech enduros like an xp12.
I now use front and rear AFX with HD rotors and on my second front blanks. Never cracked a rotor.

I don't switch for street:

Carbotechs are great cold for street.

The Racing brake tech page I think notes that cold pads work as "friction" pads, thus sort of smoothing out the deposits put on during hot cycles. This is partly my own theory, but it seems to work for me, although I don't nearly daily drive my car, hwy only between events..

The dust and noise is really bad, but I don't really care, I ignore it.

Sometimes I sort of "rebed" them to get the dust off, or even go so low as to wash the car, both work.

As for two piece rotor, I think it's really a wash. I like them in theory, but they don't seems to make the car faster, they may last longer, but they are more money. IF I could have found stock rotors prior to buying the hats, I probably would have gone that route. I do hate drilled rotors, though.

I'm pretty sure mix match rear and front rotors and/or pads is just fine. It's not like they talk to each other..


I drive in a cold climate, but those front ducts are just too tempting for me to try. I think that will complete my brake set-up! Thanks again.

AzDave47

ckchan10

I've also experienced this on multiple occasions. Once this happens, is there a way to remove the uneven pad deposits or do you trash the rotor? I've continued to drive for multiple sessions but it doesn't go away.

Also, is there a way to prevent this from happening in the first place?

80atez

There are a lot of writeups on this, I think RacingBrakes has a great one iirc.. The blueish color I think is not really removable and is a good thing, it is harder than the iron in the rotor, something called cementite or what not.... The blackish pad deposit I think can be removed. I've used garnite (sp?) sand paper when putting new pads on, that worked OK. A "light turn" could do it too, although most say you cannot turn rotors for track use.. I think the stock front calipers suffer as the pads wear and they cause uneven pad wear (mostly from heat and poor heat dispersal). Better calipers do a better job. I'll see if my caliper rebuild and SS pistons help next year as I'm still on my first set of pads from that - only did 2 track days last year.. I read of one guy who used dedicated hi-temp racing pads for street as "friction" pads between events, never heating them to the point where they "match" the rotor deposit hardness, so they are always harder. This causes them to scrape and wear the rotor more, thus "cleaning" them. Then on a track day he'd put his track pads back on.. His posts I'll never find again, but it seemed to make sense, and his experience real. I think at some point you have to either run what you got then toss them, as the uneven deposit will feed on itself and worsen.. Rebedding is always worth a try, remembering to get them hot enough, then really letting them cool for 30 min, preferably while still driving without braking.

As for avoiding it, smooth driving is key, and never letting a pad grip a hot rotor without the wheel turning. I think active handling can cause issues, but not sure why as you're always moving when it's on. It could overheat your pads though. If rears are an issue, this may be AH. I suppose ABS may also do it as it is "dribbling" the brakes, but you'd think that is so rapid it would eventually even out, and you cannot easily defeat it anyway..

If I come to a stop light, I keep my car in one spot by using my engine and clutch when my rotors are near hot so as not to spot the rotors.

I have had brakes go from vibrating to smooth on a track day, so I know it can happen. Good brakes like heat.

This is my 2c from my limited experience. Please correct me if you think I'm wrong... Politely..

0Todd TCE

Bottom of the bleeding and bedding info I send with every kit I produce in house:


AUTOMATIC TRANSMISSION ALERT If your vehicle has an automatic transmission your new brake system may be subject to pad transfer and rotor ‘hot spotting’. This is due to continuously applied pressure after stopping where the pads are crystallized to the rotor surface. Creep your car or remove your foot from the brake pedal when possible! Baking pad material to the rotor will lead to a greater chance of rotor pulsation.

ckchan10

Thanks for the reply. Everything you said seems to make sense. I definitely try not to apply my brakes when bedding but sometimes you just can't help it. I'll also try sanding the rotor if it happens again. Thanks!

AzDave47

Make sure to use garnet paper, not sandpaper as 80atez said. It is available at most hardware stores.

ckchan10

Thanks for clarifying..I would NOT have known that!

AlphaKing

Thank you very much for all the advice. I will use the Carbotech XP10 Front with DBA rotors and XP8 Rear with stock rotors for track days and Bobcats for the street. I will also swap fluid with Motul 600, add SS brake lines, and extend the cooling ducts.