Track-Addict

I don't mean because there is to much dust or they fade to quickly.

I'm questioning all the brake vendors out there as to the reason behind the problems.


Are the rotors to small / poor design.

Are the Calipers "weak"

Poor materials ?

It seems to me GM put alot of thought into making these brakes and all I hear is they are garbarge, upgrade ASAP

outnumbered

From everything I have read, they are fine for the average guy doing some HPDE's a year and for the street.

For an advanced driver I am under the impression the drilled rotors eat the pads up. The stock pads will wear too fast.

Adding R compound tires will wear the pads out quicker.

Mine have been great until the last event which required a shedding of about 80mph, and for the first time my pedal was getting soft. They still worked ok but I could feel the difference. I am sure as you requested some Pros or vendors can give more technical reasons.

allanlaw

They are not garbage, and most folks that own a Z will be happy with them for the rest of their life. HOWEVER, for hard track use, the brakes are not well matched to the awesome speeds that the car can achieve, especially on tracks that are hard on brakes (like Road Atlanta). If you can drop 2-3 seconds a lap from what you used to be able to do in your C5 or other previous car, you will be using up a lot more brake, generating more heat, etc. I've not had any problems with the brakes based on the tracks I go to and my braking style - however, I'm anxious to see what new braking system shows up on the '08 Z and may upgrade at that point.

greenshirt77

Happy happy! Joy joy! Another brake bitching thread.

allanlaw explains it nicely, but I'll throw in my .02 anyway.
The stock brakes are fine for the typical driving most people will do most of the time. In fact, they're better than fine.
Everyone seems to forget that the new Z costs what it does because not everything on the car is top notch. Otherwise, the car would cost more, and we'd be hearing people on the forum bitching about the car being too expensive.
That's why parts are upgradable. Swap out and tweak to your liking.
Remember folks, GM made a great road car that can also perform very well on the track. Not a track car that can also be driven on the street.
I think some of you are getting it backwards.

Track-Addict

Sorry thats what the quote un quote " So Bad " ? was for.

Was looking for some tech reasons why they are bad and what did Stop-Tech and others do to make them better than stock.

jvp

A few things:

1. Pad thickness
The stock caliper and rotor design do not allow for a very thick pad. That is, unless you're willing to compromise on the thickness of the pad backing plate in order to get another mm or two of pad thickness.

2. Pad material
Heat is the enemy in this case. If the pad material can't deal with the heat it experiences, then it starts to fail and 'dust' away. Then you end up rubbing the pad backing against the rotor, which doesn't do a very good job of stopping.

3. Pad cost
You buy 6 padlets per caliper up front, and 4 padlets per caliper in the back. Damned things are expensive. And aftermarket companies are just now starting to come out with replacement pads. MOST of them at rediculously high prices. It costs a butt-load of money to engineer and build a pad set-up like that, and the aftermarket companies are going to pass those costs on to you and I, until they've sold a bunch of them.

4. Rotor quality(?)
I'm putting a question mark after this one. Those stock rotors are some meaty pieces. I'm sure they've got fantastic thermal capacity, but I haven't tested them for such. The problem that folks are running into is the cracking. Under hard use, the cross-drilling seems to be a weakness in the rotor, and cracks occur. I don't know how rampant this problem is, however.

5. Heat
Air flow to the stock brake setup sucks. Period. Those "brake ducts" on the car are a joke, and really need to be built better. More air needs to be delivered as close to the hub of the rotor as possible. Not in the general direction of the inside of the wheel, like it is now.

So how does GM fix this? Well, pad material can be addressed fairly easily: use a more aggressive material. However, what does that cost? Decreased street braking performance? Decreased cold-brake performance? More noise? More dust? These things are all considered bad when it comes to street brakes. And remember: first and foremost, the Corvette, in any flavor from the showroom, is a street car. Not a race car. It needs to be engineered as such.

Even if they were to address the pad material issue, there's still the issue of pad thickness. This really can't be addressed easily, unless they make the rotors thinner. Rarely a good idea, especially when we're talking about the heat loads these brakes are seeing. So, ultimately, a different caliper design needs to be engineered. One that allows for both a reasonably thick rotor (need that thermal capacity...) as well as a reasonably thick pad.

It is these things that StopTech and other brake makers help with. Their calipers use a standard pad design; the StopTechs alone have at least 20-30 different choices for pads. The pads are thicker; StopTechs use an 18mm pad. The rotors aren't cross-drilled (you have that choice) and are still reasonably meaty enough to offer the thermal capacity needed.

I'm sure Jeff from StopTech will chime in here to discuss caliper stiffness, et al. I've read their white papers on the subject and agree with their points. But I haven't enough experience to talk to the subject, to I'll leave that to him.

Is this the type of info you were looking for?

jas (brake geek)

Track-Addict

Keep it coming thats what I am looking for.

DJWorm

Both the C5 Z06 and C6 Z06, and for that matter C6, C5, C4, Camaro and many other GM cars and trucks, use PBR Brakes (Australia). PBR also supplies brakes for GM's Australian subsidiary, Holden.

PBR upgraded the brakes from the C5 Z06, and they are better. They are sufficient for the average guy who does not track the car or engage in any AutoX. However many feel they did NOT go far enough and in fact have some design and marketing errors....basically a half-assed effort. I personally was very dissapointed.

The OEM C5 Z06 brakes were easy to upgrade for track work. The weakest link was the cheap and poor metuallurgy on the Brazilian made rotors which made them warp and crack easy. A side fault was the calipers which tended to spread with hard track work which led to pad tapper. However they could be made to work on the track with:
- Cryo'd & Heat treated rotors
- Stress relieved rotors
- Racing brake Fluid
- Racing pads
- SS Braided Brake Lines
- Cooling Duct Extensions
- Spindel Ducts
- SS or Titanium Caliper Pistons
And, of course you can always go with a big brake replacement instead.

The C6 Z06 were supposed to address some of these shortcomings and be more track ready and have more stopping power.

PBR did increase the rotor size and the swept area. They also increased the cooling to the front brakes with bigger ducts. However the huge increase in HP really makes them marginal for the track. IE the improvement did NOT match the power improvement.

- The real stupid and embarrasing blunder IMHO was the fact that they only made LEFT hand rotors and therefore the right side rotors do not cool as efficiently as the lefts on the track as the cooling vanes are backwards. Not a big deal on the street but they suck on the track. It is almost laughable.
- They also did not go to a 2 piece hatted rotor when they increased the rotor size. Therefore the new rotors weigh a TON and are great boat anchors. To get around that they opted to drill the rotos to lighten them. Drilled rotors tend to crack when heated due to the increase in potential stress risers. So now we are in a vicious circle and back to square one with rotors that tend to warp and crack and are now heavier even with the holes.
NOTE that drilled rotors do not cool any better.

The Calipers are a better design and stronger. They do not spread when used hard.

The individual padlets are a novel idea and are infact easier to change. They reduce the oppurtunity for side to side taper. But the use of the individual padlets does reduce the cross section of pad material and drops braking focre somewhat. There are however a number of problems with the padlets.
- They are too thin, therefore they wear faster and cannot accept a lot of heat
- The OEM pad material is not agressive enough for the track (that was expected)
- They are more expensive than a set of regular racing pads
- The drilled holes in the rotor cause them to wear faster
- The caliper pistons are seperated from the pad with a shim that only contacts half the pad! Therefore the pads will now taper from top to bottom.

So even if you use a racing compound on the padlets they have created a whole set of additional problems.

Although the C6 Z06 brakes offer a slight improveemnt over the OEM C5 Z06 brakes they are now installed on a car with +100 HP and are a dissappointment and the net result is only marginal braking improvement.

The real downside is that it is not even worth the effort to improve and upgrade them for the track. It is easier and cheaper to go with an aftermarket big brake system. Stop Tech is filling this gap and Gary at HardBar has some real nice custom 2-piece hatted rotors as well as a Caliper replacement.

greenshirt77

Sorry I couldn't give any "tech" reasons, but I'm curious- what difference will it make?
If someone's not happy with the stock brakes, there are multiple options for upgrading them. Why complicate things by dwelling on all of the minute details regarding the "why?", instead of just concentrating on a solution.
The stock brakes are not horrible brakes by any means, but for those that find them sub-par, swap those babies and be done with it!

Track-Addict

I really don't want to upgrade my brakes after all I just paid 78K for my car but I bought my car to put on the track and autocross.

I would like to see if it's worth changing a few parts.

For example change the pads and rotors but leave the calipers.

So I'm gathering intel

However I'm leaning toward a full kit

Boulder GT3

I'm right where you are. In my experience it's just not worth screwing around with the brakes. When you go to the effort to get to the track and so on you want to be able to drive hard and not have to baby the brakes or work on the pads and rotors. Front kit for me shortly.

Track-Addict

Call me a nut job but I can't do just a front kit.

I couldn't stand to look at my vette with Corvette logo rear calipers and Stop Tech front. Can I special order my Stop Techs with the Corvette Logo.

J Ritt

DJ Worm covered the bulk of it. As he said, the brake requirement of this car is a big leap forward vs. the C5Z. The speed of the car is the key element, which is what he was getting at. If you look at the first equation on this page, you'll see that the last variable is velocity. http://www.stoptech.com/tech_info/Th...%20Systems.pdf
Notice that V is squared...that's the key. Gnerally speaking, when the C6Z gets to the end of the same straight, it is traveling quite a bit faster than a C5Z would be at that same point. The thermal requirements increase exponentially as velocity increases, while mass increases are linear. A lot of my customers say, I added a roll cage to my car, along with an oil cooler, and a big radiator. I need more brake now that my car is heavier...um, not that big of a deal really. Now, take the guy that guts his interior, puts on lightweight wheels, sticky tires, an exhaust, intake, heads and cam. He will weigh less, but he will be exiting corners faster, have more power down the straight, and hit substantially faster speeds at the end of said straight. Even though his car weighs less, his thermal requirements will be much greater because of the increased velocity, which is squared.

So, how do you provide for the increased thermal requirements?
1. Rotors- A rotor is a heat sink. It needs to be sizeable to hold the heat generated in a braking event, and it needs to flow and evacuate that heat. GM provided a large directional rotor, but they put one rotor on the car spinning in the wrong direction! That means that on the right side of the car, airflow is not optimized through the rotor. The relevance of this situation becomes greater at track speeds. More heat is generated when slowing from a high speed, and you need as much airflow as possible on the ensuing straights after those types of stops to cool the system back down. Turbulence in the rotor does not allow heat to dissipate through radiation. In simple terms, the hot air "hangs around," rather than being drawn out through the wheel, etc. As temps rise, all sorts of bad things happen...pads overheat, rotors expand and deform (coning), brake calipers heat up, which heats brake fluid, etc. Plain and simple, heat is the enemy of brakes, and anything that can be done to optimize the coolling of the brake system will typically pay dividends.
Drilled rotors are designed to give more leading edges for the pads to bite into. They also save weight, and help with water evacuation. That said, StopTech never recommends drilled rotors for track use. When they expand and contract under track conditions, they crack more easily than slotted or plain rotors. It doesn't matter if the holes were cast in or not.
One piece rotors are not ideal for track duty either. As a rotor heats, it expands radially (larger in diameter). When this occurs on a 2-piece rotor, the iron is allowed to 'float' on the aluminum hat and drive pin system. See here for more details: http://www.stoptech.com/tech_info/fa...rsystems.shtml
When a 1-piece rotor expands, it can't float. That means the rotor cones. Imagine a rotor lying flat on the table and expanding radially. The outer edges of the rotor would pull up off of the table as it tried to grow outwards. Now flip that rotor vertical and imagine it on your car. That is coning. Now think about what that would do to your brake pads if the outer edges of the rotor were pulling in towards the hat. The pads wouldn't wear evenly, or contact the rotor cleanly. That's pad taper. Those are the things 2-piece rotors are designed to avoid.
Additionally, aluminum hats allow for a large weight savings. You can go to a much bigger rotor (heat sink), without adding much weight by using an aluminum hat.
Why is our rotor system better? On this car, it uses the same size iron as stock (355x32mm), but it flows much more air due to the patented internal vane design: http://www.stoptech.com/products/BBK..._airflow.shtml
We could have gone to a bigger 380mm rotor, but then you start limiting yourself more on wheel and tire choices. Generally speaking, you only want a rotor large enough to handle the thermal requirements. Anything more is simply dead weight to drag around.

In summary, the difference between our rotor system vs. the factory C6Z setup is that our rotors run cooler, weigh less, don't cone, are less prone to taper your pads (so you get more life out of them), don't crack as easily, don't heat the calipers as much, and don't boil the fluid so readily.

Finally, I don't know specifically what the metallurgy is on the stock units, but we spec our own metallurgy with some objectives in mind. We have special 'ingredients' to combat crackage, pad adherenece, wear, NVH, etc...a long list.

That's just the rotors. I'll try to put some time in on other aspects tomorrow. For now though, I'm tired and I'm going to bed.

J Ritt

This is probably the single most common response I get from our customers after adding our kit. They tell me that they can focus on driving and enjoying the car, push as hard as they want without worrying, etc. I've found the same thing on my cars. To anyone that's had a finicky coilover setup that they couldn't dial-in, less than adequate brakes, or a supercharger that throws belts...there's not much better than a great day at the track when your car performs flawlessly. With all the prep, money spent, and limited track time, there's a lot to be said for simplicity and reliability.

J Ritt

If anyone laughs at your 'mismatched' brakes, just step on the gas and they won't have to see them anymore. Unfortunately, we can't do any special logos.

Serously though, a front kit looks just fine. If you got red, you'd have to look close to see what was going on with the logos, etc. I don't think anyone that knows a lick about performance driving/racing would bag on you for having a higher performance front brake system on the car. For those who would, you probably wouldn't care about their opinion anyway, because they don't even know what they're looking at or talking about.

ranger1

great thread...

Garry

outnumbered

Keep the info coming Jim.

Jaxian

From what I hear to this day the fastest way to get a Porsche brake engineer and and Porsche marketing guy in a fight is to suggest removing the drilled <cast holes> rotors from the 911's. The engineers have been trying to get them removed for 30 years from street cars but marketing will never let them do it because its such a 'expected performance/race item' to the average know nothing Porsche buyer.

The engineer said something to the effect of 'can you imagine driving at 120kph on the freeway for a great distance never hitting the brakes then all the sudden making a panic stop and taking the brakes from ice cold to melting hot in one instantaneous cycle. No warm up time, no slow cool down time as you get right back to speed. Now do it twice. Then you go buy new rotors.' Crossdrilled rotors on high performance street sports cars are like 20 inch rims on an Escalade, essential marketing items only.

I always liked the slotted only rotor. Added gas removal, greater initial bite than smooth, but none of the cracking issues of crossdrilled. Sadly every single aftermarket brake manufacturer in business knows he has to offer crossdrilled rotors if he wants to stay in business, even if they aren't the best solution. The customer keeps them in business and a lot of them have been brainwashed into thinking they must have crossdrilled rotors on their street cars. Ain't marketing wonderful.

OregonC6

Interesting to note the word from this expert that does not recommend drilled rotors for track use. All you hear in the regular C6 discussion area is how superior the Z51 drilled rotors are for the 'track'. Since I own only the 'base' C6 and have never and will never take the car to the track, I can't comment from experience on Z51 or Z06 brakes. I will say though that the base brakes are just fine for what I'd call 'sane' street driving. Therefore, Z51 or Z06 or any aftermarket upgrade from base is for 'special' duty either on the track or street.

I would be curious to hear an experts comparison of the C6 base, Z51, and Z06 brakes. If the Z06 is the best and were to score 100 points what would score would you assign to base and Z51? I know some are saying that Z06 are poor brakes but my question is relatively speaking how much better are they than base and Z51?

All the discussion I've read about brakes leads me to two conclusions: 1/ If I upgrade my base brakes I will get larger rotors OR slotted rotors but NOT drilled. 2/ If I should get a Z06 I would be very satisfied with the brakes for my street driving.

any opinions expressed are mine alone
have a nice day.

Track-Addict

But

How about the other vendors ?