TheKomoman

My wife is stepping up to Hoosiers so it's time to step up the brakes in her C6Z. I run the AP 8350 setup on my '02 C5Z and I'm considering putting the same setup on her car so we can share spares rather than just upping the compounds on the factory brakes. I would assume that would net her better braking performance as well but I'd like to hear experience of anyone that has put 8350's on a C6Z.

Secondly I would like to improve the pedal feel on my C5Z. The pedal travel is very long and that is independent of bleeding or fresh pads. The pedal isn't soft, it just travels a long way before I get response and it leaves my foot below the level of my gas pedal, a heel-toe pedal installed by previous owner, and that makes blipping far more difficult than I'd like. I have no C5 experience beyond this car so I'm wondering is a long pedal common in C5? I intend to put the factory gas pedal back in but it still feels like that brake pedal should respond faster than it does and I know that self-preservation kicks in and keeps me from being comfortable enough to push farther.

I've done a lot of reading and searching here before posting but nothing that jumps out at me. So thoughts, experiences, suggestions all welcome and very much appreciated!

CHJ In Virginia

Can't help much on the C6 question, but here is some input on the C5. There is something not right on your brake system. The pedal travel is way too long if it is sinking below the gas pedal. My C5Z with Wilwood BBK takes 1.5" travel to start pad engagement. Full on ABS stop engagement is about 4.5" travel.
Several things come to mind on your travel problem. 1) too much play in hubs - replace with SKF race hubs 2) Improper bleed - do again and use a TechII to cycle the ABS unit and make sure that there is no air in it. 3) Improper size master cylinder for your front calipers. The volume of the pistons might be larger than the MC can easily deliver. You did not mention what type of rear calipers you are using - if aftermarket multi piston units they could also contribute to the volume problem.
Good luck on getting it figured out.

UstaB-GS549

I have the AP kit on my C5 Z06 and pedal travel is minimal. I would check all the things mentioned by CHJ.

You might want to check the three bolts holding the bearing to the upright. If they are loose it could be a factor.

Is the long travel only on track? If so, I would look more for something causing piston knock back. Are the AKB springs in the calipers?

TheKomoman

You're not the first to suggest checking the hubs, definitely on my list, especially since it's a known weakness. I'm running the factory rear brakes so hopefully it's not a master cylinder issue, seems like the AP kit is pretty regularly installed so probably not the issue. Hate paying for brake bleeds since they're so easy, but a lack of TechII hardware in my garage will force my hand on that one if I don't find another obvious problem.

The AP's certainly come with AKB springs, but I haven't pulled them apart to look for them. The long travel is hard braking, I can brake around the paddock without having to push way in, but I don't street drive the car. I'll check the upright bolts.

Thanks very much guys!

mbeckers

I had the AP 8350 calipers on my C6Z and I was very happy with them. I did not experience the long pedal feel as you described in your post. I had Hardbar's T1 kit and they were a good improvement over the stock system.

Supercharged111

You know, my car has the long pedal too and I've always felt that it's never been quite as stiff and responsive as it should be. I just learned to accept it. Then I bought a Camaro road race car (CMC for you NASA folks) and it came equipped with C5 front brakes and Hawk DTC60 all around. The Hawks seem to take a few laps to get up to temperature, but that Camaro has sooooooooo much more communication in the brake pedal than my Corvette it's not even funny! Same front brakes, but they feel a jillion times better once up to temperature. I barely noticed a difference between cold and hot pads in the Corvette. My guess? ABS pump, it's the only wildcard between the MC and the calipers. I don't even think it's air in there, I just think there's something in there giving way. Some mysterious bellows or an aging rubber piece? Or maybe just an inherent design flaw.

ZedO6

Based on what you describe above ...fresh pads, clean rotors, fresh bleed, long pedal. I'd agree with CHJ, either you have air in the system or somehow have the wrong master cylinder which isn't moving enough fluid.

To diagnose loose hubs, idle through the pits and saw the wheel half a turn each way and apply the brakes. The pedal should be at its worst. After that stop try it again with the wheel straight and you should feel a notable difference. IMHO, pedal travel from loose hubs won't get much worse when the brakes are hot.

z06801

On my C5 Z06, the Doug Rippie master made a huge difference, always a consistent pedal

JerryTX

I'll vote no way the AP 8350 is adequate on a C6Z for an aggressive driver. They didn't survive on my 440rwhp 3250lb C6. Look at a bulky built 6 piston like stoptech st-60 or Brembo or the new 6 piston AP stuff being kitted for the C6. Talk about caliper flex and soft pedal..

paoutlaw

One thing that is not mentioned are the brake hoses. If the stock rubber lines are still on your car, they could be a problem. Replace them with stainless brake lines to the caliper for a much firmer feel. Other than that, it sounds like you have air in your brake system. Anytime you get the brakes very hot the brake fluid may boil. When the brake fluid boils, air will be in the brake system and you will need to bleed the brakes. Hope this helps.

The Outlaw

JRitt@essex

I know it's been debated many times, but I believe the C6Z has a handling advantage largely due to the tire widths vs. the C5Z. As such, it gets through and out of many turns quicker. The engine difference between the two cars is tremendous. I've driven both on track, and the 7.0 L made my LS6 feel like a dog. Terminal velocities are higher on the straights, which means more energy to turn into heat. Combine that again with more tire under braking = more heat capacity required.

My advice for a C6 Z06 on Hoosiers would be our new Endurance six piston/355mm kit. It clears the OEM wheels easily, offers more heat capacity in the discs than our CP8350 kits, larger pads, ventilated pistons, etc. We designed this kit specifically with your situation in mind...C6Z on stickies. There are competitive kits out there, but nothing has the laundry list of heat-resisting components that our new kit has. It even has the exact same discs that the Corvette Daytona Prototypes won the championship with last year...72 vane, AP Racing endurance J Hook units.

Pre-orders for the six piston kit are open this week with a few nice bonuses (free shipping, fluid, etc.), but close next week when the kits will start shipping. Shoot me an email and I'll give you all the details. Or you can see more details in this thread. It's a bit more money than the smaller kit, but keep in mind the greater heat capacity will mean that you're burning through spare pads and discs less frequently than you would be on the smaller kit, so long-term running costs will balance out.

As for the long pedal, there is something wrong. I'd chase down what others have said. Our CP8350 Sprint kit was designed for use with the OEM master cylinder (as was the new six piston kit), so no integration issues there. If you can't sort it out and want to escalate things, myself or our engineers can try to help...contact me as above. Between the Hardbar T1 version of the kit, and our own Essex Sprint kit CP8350 kit, there are hundreds in the field. I've never had anyone complain about a long pedal. It should be high and hard.

I forgot to mention...our kit saves 24 lbs. of unsprung weight off the nose of a C6Z06!

TheKomoman

Thanks to all who responded!

For the C5Z I really don't think it's as simple as a bleed and go, I've done several bleeds on this car and not had any luck with changing that. I will be checking the items mentioned above, especially the hubs.

For the C6Z there's a lot of food for thought, not the least of which being whether I want to spend a bunch of money converting this car or perhaps just buy something "finished."

Thanks again to all and to any who may still contribute.

KNSBrakes

Any reason you won't at least try the C6Z w/ hot(ter) braake pads? While they might not be the ultimate they are still a big fixed caliper setup that can deliver. Add brake ducts and go run it.

TheKomoman

I figured I'd start there, absolutely, and I put brake ducts on it a long while back. Just trying to flesh out my thoughts long term. After reading some of the ASA/tube frame threads I can't help but wonder if long term that might be the way to go for both of us instead of caging our current cars, etc etc etc.

KNSBrakes

I think I'd sell a street car a buy a prepped track car (Corvette or otherwise) rather than build one. Much faster and cheaper I bet depending on how much mods you already have done/can undo.

I spent quite a bit more than my car is worth.

ZedO6

A quick look around CF and there are WAAAY too many caged track prepped C5's and C6's for sale (and for reasonable money) to consider doing that to a street car.

TheKomoman

Agree with you both, and that's what has my head currently spinning, since my decision is really x2!! I swear sometimes running two cars costs 4x the time and money....

The C6Z aside from brake ducts, harness bar and race seat is still stock so that one is easily return to street car duty. And frankly we're on our second LS7 (first replaced under warranty) so that lump makes me nervous anyway. The C5Z was another forum member's hybrid track/street car that was leaning hard towards track and I've taken it a little more that way. It has T1 bars, Pfadt coilovers (Gen 1), the AP brake kit, roll bar (just the bar, no cage), 2 race seats, big aluminum radiator, etc so that one is a bigger question.

ZedO6

Well the C5Z IMHO may be far enough along to keep going. I've done the street/track/back to street to sell thing several times with Porsches and BMW's. Keeps things fun and you can bail out for not a huge loss since you are still selling a "street car". Of course I was not looking for FTD with these cars, just keeping my skills sharp without breaking the bank like when I was racing.

However, when you're making irreversible modifications. Drilling and cutting for a roll bar, won't be easily explained at sale time. Also, consider that the C5Z is probably worth half what the C6 is worth, makes that decision easy. Toss in the LS7 concerns....which is why I track a C5Z.

As for running two cars....no easy answer there!

cruzin2

I found that with carbotech pads, titanium shims and cooling to the rotor, I got 90% of the way there. This may be enough for you, don't know.

After I starting running 3-4 track days a year, the rotor and pads costs got excessive. I was running through a set of pads and rotors every 3rd track day.

I ended up finding lightly used brembos that are amazing! No more bleeding fluid at lunch time at the track. Zero fade at big tracks like mid-ohio. I've run 5 track days on one set of pads and 10 days on the same rotors. Probably have at least one more day on the pads and 2-4 on the rotors.

ZedO6

I'm there right now...which Brembos and what rotors? I'm tired of marginal brakes that really compromise an otherwise very capable track car.

Apologies to TheKomoman...no hijack intended.