On track brake failure, 2012 ZO6
 

Took my '12 ZO6 to Watkins Glen. Pedal straight to the floor near the end of the first session into the bus stop. Exciting but all is well.

I have the DBA two-piece rotors, Motul 600, OEM lines, Quantum cooling kit. All essentially brand new. Carbotech 12's up front, 10's in back.

When I got back to the pits there was brake fluid all over both of the calipers and wheels. Not enough to where the reservoir was really low or anything. Just enough to ruin the calipers.

Wheels off, bleed, confirm the bleeders were on firm and reset them, cleaned it all up and went back out.

Second session I was doing the left foot double pump prior to corner entry and while I never lost the pedal, it got soft so I went in.

Same deal basically.

The DBA rotors have three paint markings in them. The hottest one is 1160. It has changed color so my rotors are really hot. I am threshold braking and doing so from 156mph so far but nothing others aren't doing as instructors.

So, I guess I have three issues.

Very hot rotors

Leaking bleeders..

Lastly, now I have ruined the paint on the calipers. Big time.

I've also lost faith in these brakes. I do the brake work. Have for a long time. We all know what a proper bleeder torque feels like. Somehow, these obviously got over torqued and now the caliper bleeder seat must be deformed. Replacing them seems silly, without an upgrade. Upgrades are way expensive.

I believe the bleeder issue is either a weak point by design or they were improperly serviced at some point before I owned it. It just isn't that hard to do right. The car is going in to the dealer Friday but I have no idea how they will react. I bought it in Detroit and this is the first vist locally to a dealer for issues. I think they should be replaced. They are nasty looking and will always leak now.

Looking at StopTech, AP, Brembo etc. but not liking the cost.

I've never had trouble with the bleeders and I think the OEM lines may be your weak point. I just took our 2008 Z06 out of track day service and had to replace the crush washers on the LF caliper as it wouldn't snug up. I think it would be money well spent on a set of braided lines. I've used the lines Rippie sells and just installed a set of Spiegler on my '01 Z06 dedicated track car. The lines Rippie sells have connectors that go straight in - no banjos. The Spieglers do use banjos but I don't know that it would scare me off them. I think it would be money well spent on either or really any braided line.

You may just need a real good flush of the brake system. a student of mine had the same problem at Sebring this spring his mechanic had flushed and bled his Z but apparently there was still bad fluid in there!
(we fixed it so it was a really good bleed that worked)
next try some new bleeder screws first.
If you need to upgrade after that look at the Wilwood from Todd at TCE
http://www.tceperformanceproducts.com/ (forum vendor) :thumbs:

My dad told me about your issue. Assuming you keep your current stock setup:

1) I would certainly put SS lines on the calipers. Don't think that's your problem but it can't hurt.
2) In that car with your speeds I'd switch to Castrol SRF.
3) Get some speed bleeders on there.
4) I had the same thing happen in my dad's GS, and it was indeed boiled fluid. He doesn't brake too hard, but after we switched to RBF600 he hasn't had a problem since, and I haven't boiled the fluid driving his car either. But if it was MY car I'd certainly put SRF in it.
5) I can't believe you're going 156 into the bus stop. That extra 100hp must be nice!
Edit 6) I would also "pad up" to the XP24 in the front. They take alot more heat than the XP12 and it sounds like heat is an issue for you.

But I know how you feel not being confident in the brakes. These cars are too fast not to feel confident in the brakes. My C5 never felt good until I switched to the AP kit. Haven't changed a rotor or even thought about my brakes since. It's pricey but it's better than dieing I always say.

Before doing anything else he needs to find and fix the fluid leak! Have you actually confirmed that it's the bleeders?

- car on jackstands, wheels off

- clean all the fluid off. Use lots of water.

- blow it dry or wait for it to fully dry off.

- start engine then press the brake pedal, hard. 10 seconds or more.

- grab an inspection light, go find that leak

Probably will go SRF once I figure it out. I plan on using ss lines too. It is too hot around those rotors for rubbber. Anyone else seeing 1150 degree rotors or so?
The DBA fronts are two piece but uni-directional vanes. Ie, straight vanes. Wondering if those pull less air?

After the first pedal loss I pretty much did all that flink. In fact a buddy was at a parts store near the Glen and got new bleeders. Carquest. They were the wrong length.

So, I had the wheels off, looked carefully and the fluid was clearly coming out of the outside bleeder valve area, not the inside.

I cleaned it off very well, bled them, inspected the bleeder valves and tightened them down again. If they were leaking before I had no alternative but to make real sure I was snug so I can tell you a loose bleeder was not the issue. I then had a buddy stand on the brakes. No leaks.

It was all down the caliper face and on the wheel. The wheels are fine, the caliper is a mess. Crappy caliper paint for sure on OEM calipers.

I believe but did not check because my brakes were cooler in the pits after driving back in slow, the calipers must be getting close to the temp to boil the fluid if the rotors are 1160.

So, I'm thinking, bleeder leak, then air gets in for a guaranteed pedal to the floor moment and on top of that, I'm perhaps at a fresh dry fluid boiling temps. Could be.

Leaning heavily towards the StopTech front calipers, rotors and new pads.

As an aside, I don't know what the Carbotech 12 front pads are temp rated at but they felt awesome all session until I must have gotten it all so hot this happened.

I wonder if at the super hot temps I'm generating, the aluminum caliper expands differently than the steel bleeder and hence the leak. That and they were likely over tightened at some point and that may not have helped the bleeder where it contacts the caliper seat and seals it.

I've had leaking bleed screws in the last where a piece of gunk was stuck in the seat. To check, completely remove bleeders and let fluid flow out. Look down with flashlight for debris. If anything is in there, use needlenose pliers or hook to retrieve.

A word of caution... Brake fluid gets everywhere so be ready.

That will fix it :thumbs:
if your hitting 158 before the bus stop, your putting some serious hurt on stock brakes :D

I run StopTechBBk front (ST60) and rear (ST40), and My car (2004 Z06) has a high hard pedal and ZERO track issues!!!!:thumbs:

This is after washing them as best I can tonite with wheels on. With the wheels off it did only appear to be the outside bleeders though.

That is always a scary situation! Yes definityl sounds like an issue with either the bleeder valve or hole being stripped or over tightened previously. Definitely replace the bleeder valves...and maybe replace the caliper just to be safe.

Did you cycle the ABS when bleeding?

I spent several track days drinking around with the brakes. Finally broke down and got the 380mm brembos. Now I swap fluid once a year and swap pads before each event and have never had a brake problem since. Plus the capability of the car is much improved.

One note, bleeders do not seal with the threads. The threads simply allow for pressure to be applied to the bleeder when installed. The cone on the end of the bleeder screw does the sealing. Just like an "AN" fitting. Very little torque need be applied. If the cone of the bleeder and/or it's mating area in the caliper is distorted or has debris the seal will be poor. It is often mistaken and installers crank down on the fittings creating permanent damage. You can change the bleeder with a new one, but the caliper is aluminum so if it has been damaged you are out of luck.

I would never again track the car with the stock defective show brakes. Mine spit the pistons out on a brand new car and damn near killed me. I had to slalom all kinds of large objects on the parking brake while downshifting ... And the only warning was the tiniest bit of fade on the last corner prior to the straight. If i had not let up i would be toast.

I have stoptechs now and they are worth the money for sure. And in 3 track days will probably have paid for themselves.

No. I cycled it on track.

Agreed. Super description. What confuses me is why they don't leak pressure checking them in the pits but on track at the hottest temps do leak.

Different metals between bleeder and caliper. Crappy caliper? Maybe they are in fact starting to weep as the car warms on track but the process takes a number of laps to get to the point where the result is pedal to the floor.

To know I'd have to come in after maybe five laps and see if they are leaking. Wasn't able to do that because I didn't know it was happening.

If the bleeder is not OEM it may not have the correct angled sealing surface. This is an issue with C5 calipers. When hot, there may be enough variance in the metals (steel vs aluminum) to cause a leak due to the sub-par seal.

The potential reasons for failure seem to have been covered fairly well already. I gave some input in a similar thread the other week that can be seen here. I put a few points about leaking bleed screws in that one. The OEM C6Z06 brakes are not a very good track setup, period. That has been proven over and over again. Every component in the system has weaknesses. Even with aftermarket discs they aren't a great solution.

I'd ask that you take a hard look at our front six piston Endurance front kit.
You can read our blog for recent reviews.

Someone on a different forum asked me to do a comparison to the StopTech ST-60 front kit, and it is relevant here:

I was actually the sales manager at StopTech for roughly five years before taking on my current role at Essex/AP Racing. While at ST I was also involved in just about every part of the process of bringing their products to the market (production, product mgmt., component sourcing, etc.). I doubt there is anyone more uniquely qualified to compare their system to ours. Below is a comparison of the components in our kit vs. those in the StopTech setups, but this info also applies in the same manner to other high performance street big brake kits (painted calipers, aluminum pistons, dust boots, drilled discs, etc.) currently on the market.

Here's the breakdown as I see it.

Calipers
Essex version of the AP Racing CP5060 six piston vs. StopTech ST-60 six piston

Anti-knockback springs
AP Racing has them, StopTech does not. People severely underestimate how valuable these springs are. After going through S turns, you'll have a much lower pucker factor in the next brake zone with the AKB springs installed.

Piston type
StopTech= cast aluminum
AP= machined stainless steel, domed back, ventilated
Stainless steel is far superior at keeping heat out of your brake fluid vs. aluminum. The domed back on the AP pistons adds substantial stiffness, which can be felt as a firmer pedal. The ventilation on the piston edges allows for more cooling air circulation. All of these features add up to greater heat rejection around the piston area, ultimately leading to a lower chance of brake fluid boiling and resulting fade.

Weight
StopTech ST-60 is 8.9 lbs.
Our version of the AP Racing CP5060 weighs 6.2 lbs. without pads...approximately 3 lbs. lighter per side than the StopTech ST-60.

Dust Boots
StopTech is a street caliper, and as such uses dust boots. The AP CP5060 has none. If you've ever run dust boots on the track, you'll find that they burn up and cause a big mess almost instantly. Their only value is if you're driving on winter or debris/dirty roads. As soon as they go on track they essentially lose all value.

Seals
Both calipers have quality, high temperature seals.

Pad choice/cost/size
The ST-60 and AP Racing CP5060 use the same basic shape (it was originally an AP Racing shape, implemented many years ago. The D54 radial depth version we use in the CP5060 has an additional 3 mm of surface area along the lower edge, giving a bit more pad volume vs. the D51 pads in the ST-60. Pricing on the two pad shapes is the same.

Stainless Steel hardware
Both calipers have quality stainless steel hardware.

Footprint/size
In addition to weighing much less, the CP5060 has a smaller footprint and tends to offer superior wheel fitment.

Finish
StopTech= painted. Look pretty, but will not look as good after hard use. Red turns maroon/brown, etc. Paint and powdercoat tend to color shift dramatically at track temps. If you're driving through road salt however, they will be better protected than anodized.

AP Racing= anodized. Look 'racier' (like what you see on full-blown race cars like the factory M3 racers) and do not color shift nearly as much. I tell people that they go from grey to ugly grey.

Bracket
Both have high quality anodized aluminum brackets and aircraft quality hardware.

Rebuild Service
Essex offers a lifetime professional reconditioning service. For a $150/caliper you can send your calipers to Essex and have them rebuilt by the same techs who service calipers for NASCAR Sprint Cup and ALMS teams. StopTech can rebuild I believe, but I'm not sure how formalized their procedures, policies, and prices are at this time.

Discs

Design
Discs from both manufacturers are quality castings that are crack resistant and will last a long time under heavy track use. That said, the AP Racing discs are a heavy duty 72 vane internal construction, and patented J hook face slot are the #1 choice at the elite level of motorsports (NASCAR, ALMS, DTM, Super GT, etc.). The exact same discs in our kit won the 2012 championship on Corvette Daytona Prototypes. The StopTech's are only a 48 vane disc with a conventional slot pattern.

Disc hats
Both have a quality design and are made from high grade, anodized aluminum. Both are optimized for weight and airflow.

Weight
Essex/AP Racing hat/disc=17.6 lbs.
StopTech hat/disc= 21-22 lbs.

When you combine the caliper and disc weights, our system weighs 9-10 lbs. less per side vs. StopTech or 20 more lbs. off the nose of the car.

Spare Disc Price
Even though the AP discs offer far more features, pricing is almost the same as StopTech's recently increased price per disc. Replacement iron prices per disc are as follows:

$359 Essex/AP Racing Sprint Kit (355x32mm)
$360 for the StopTech 380x32

Other Items

Wheel Fitment
Our Essex Comp kits sit inboard of the StopTech setup a bit, offering superior clearance. I'd need to check to find the specific difference. Obviously with a smaller diameter disc, our kit will fit many/most 18" wheels, whereas the StopTech kit will not.

Brake Lines
Both systems came with a high quality set of brake lines. The Spiegler lines in our setup use all stainless steel fittings made in Switzerland (assembled and tested in Ohio). The fittings on the ST lines are not quite to the same spec.

Racing Pedigree and Brand Equity
While I'm far from a brand snob, I'd say it's safe to say that AP Racing gets the nod in terms of brand equity, racing heritage, and pedigree. StopTech has had good success in the lower ranks of racing (World Challenge, Grand Am, etc.), but AP dominates at the elite level. Virtually all of the factory Corvette race cars use AP Racing (including the C5.R, C6.R, and C7.R), DTM, etc. Not to mention AP dominates many of the 'money-no-object' markets when teams have a brake choice (non-spec) such as NASCAR Sprint Cup (which btw are extraordinarily tough on brakes, even though they're typically going in a circle!), Super GT, ALMS etc..

While our system is a bit more expensive than the standard StopTech ST-60 kit, you're getting a lot more technology for your money. If you peruse the list above, you'll see that every component in our kit meets or exceeds their specification, and is more closely aligned with professional-level race components. That is intentional. When you factor in the fact that the higher specification components will need fewer replacements, the running costs over a year or two will balance out quickly, essentially negating the initial price difference. You'll also be saving about 9-10 lbs. unsprung weight per front corner with our kit!

Ultimately both companies make a great product. I had an ST-60/ST-40 14" BBK on my Z06 while I worked at StopTech (and an ST-40 kit on my 350Z). Both were solid products made by good people. I'm also still friends with a number of their employees (since I hired and trained most of their current sales staff). When we put our Essex Competition Kits together however, I tried to look at every piece of the StopTech system and produce something that eclipsed its performance, all while keeping the costs at a level that the average enthusiast could afford. My past employment there put me in a perfect position to accomplish this task, and I believe we have succeeded...more technology borrowed from pro racing, higher specification, lower running costs, better fitment, etc. I believe what we're doing is taking things to the next level for the average club racer, HPDE student, and autoX'r, and giving them access to previously unobtainable technology and performance.


We have a complete matching rear big brake kit that you could buy later if needed.

Also, Essex is a forum sponsor, and I've helped tons of guys here with brake issues (and will continue to do so).:cheers: