I have a 2008 Z06 only about 3 1/2 months old... 4800 mi on it. I brought it to Chevy b/c the brakes were shaking (fluttering feel) at around 65-70 mph. Completely ridiculous and unacceptable. They cut the rotors, and said that I can never get them wet when they are hot. WTF??? A) I never wash my wheels directly when they are hot. B) IF they got wet while driving from the rain... should they warp to the point that they shake when braking at normal speeds? Something tells me this wouldn't happen with Brembo's, etc... Is it normal? I'm assuming NO?!?!?
UPDATE:
The brakes started shaking again (after the first cut) so I brought it back...
After accusing me of "driving too hard", and then giving me the run-a-round for 2 days, Chevy tried to act as if they did me a favor by replacing my defective rotors. I just have a hard time believing in that "break-in" period. They are warrantied to go from the showroom to the track (the only car that is from my understanding!) - anyway... if I have never "tracked" the car... so how hard is "too hard" for racing brakes? I'm totally disgusted. I have to be afraid of braking to hard in a $75k sports car? One of the best in the world? Something isn't right. I have driven everything from old Chevy Camaro's to Infiniti's to BMW's... and NEVER have I had to worry about heating up the brakes. This is absurd!
I have an 08 w/ 4500 mls and I think the brakes suck. I did the proper break in they just suck. I knew on the c5z I would have to upgrade especially for the track. After looking at these brakes I thought I would be set mabey just different pads. Nope, do a search on the C6z brakes here and you'll see that bottom line there is no hope except to swap out to better calipers like stop tech I believe it was from LG Motorsports. Yeah just what I want to do after spending 75 grand!! I really regret stepping up to the C6Z. I should have stuck w/ my 03z and threw 5-7 grand at it. This was a big mistake. I traded a great car and had to add 45 grand to get a car that has the same issues and is just a little faster. Big mistake.... sorry just venting... Jim
Let's examine your concerns and statements one at a time.
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They cut the rotors, and said that I can never get them wet when they are hot.
That is absolutely true. It is NOT a good idea to deliberately spray water on hot rotors, which you said you don't do. Very well, because rain is not what they were referring to.
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B) IF they got wet while driving from the rain... should they warp to the point that they shake when braking at normal speeds?
No, brake rotors do not warp from simply getting wet while driving. In fact, the word "warp" with respect to brake rotors is something of a misnomer. They seldom if ever 'warp'. The cause of the pulsations you feel is due to uneven pad buildup on the rotor surface.
Not to sound like an ass, but write that on a whiteboard 500 times. As to what causes this is quite simple: You do. Again, I'm not pointing a finger, I'm simply telling you the unbiased truth. Ones braking habits are typically what cause it. There are a number of habits that can lead to uneven pad buildup and I will only state a few...
- Improper break-in
- Jabbing the brake pedal
- Hard braking, letting off the pedal, then braking hard again...repeat
- Track use, depending on braking habits
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After accusing me of "driving too hard"
I don't know what they told you exactly, but I doubt they were truly "accusing you". They were likely pointing out or alluding to one or more of the things I outlined above. If so, they were correct.
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I just have a hard time believing in that "break-in" period.
Believe in it! It's absolutely and unequivocally true! Go to any well respected brake manufacturers website and read. I suggest StopTech's site.
Brake pads and rotors need to be properly bedded in (mated to one another). That means an EVEN LAYER of pad material must be deposited on the rotor sufaces. If the brake pad deposit layer is uneven you will experience pedal pulsations and that feeling of "warped rotors".
Write that on the whiteboard as well.
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They are warrantied to go from the showroom to the track (the only car that is from my nderstanding!)
That's a misunderstanding. They are warrantied for street use. NO PRODUCTION CAR is warrantied for track or racing use. None. Not a single one. Racing or other competitive use is not warrantied. Neither is abuse or misuse. That is per your owners manual.
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so how hard is "too hard" for racing brakes?
First, they are not "racing brakes". They are simply brakes. Secondly, "How hard is too hard"? It appears you already discovered that. Again, I don't mean to sound sarcastic. I'm telling you the truth. Whether you want to HEAR it or not is up to you.
What to do...
- Go to the site I mentioned and read. Read about proper break-in of pads and rotors. Read about uneven brake pad deposits and what results from it.
- Take it easier on your brakes, especially with new pads and/or rotors.
- Squeeze on your brakes and maintain an even brake pedal pressure. Don't stab at the pedal.
- Try braking sooner. You dont have to wait til you see God to brake (on the street).
Lastly...
You are not driving a race car. As much as you may like to believe that, you're not. Treat it like you would any other car. Yes it is faster. Yes it makes for a better track car, but it is not designed explicitly for that purpose. Disregard what the GM marketing droids may lead you to believe. And yes, much of it is indeed misleading. And yes, they exaggerate. Remember, their job is to SELL cars.
Let's examine your concerns and statements one at a time.
That is absolutely true. It is NOT a good idea to deliberately spray water on hot rotors, which you said you don't do. Very well, because rain is not what they were referring to.
No, brake rotors do not warp from simply getting wet while driving. In fact, the word "warp" with respect to brake rotors is something of a misnomer. They seldom if ever 'warp'. The cause of the pulsations you feel is due to uneven pad buildup on the rotor surface.
Not to sound like an ass, but write that on a whiteboard 500 times. As to what causes this is quite simple: You do. Again, I'm not pointing a finger, I'm simply telling you the unbiased truth. Ones braking habits are typically what cause it. There are a number of habits that can lead to uneven pad buildup and I will only state a few...
- Improper break-in
- Jabbing the brake pedal
- Hard braking, letting off the pedal, then braking hard again...repeat
- Track use, depending on braking habits
I don't know what they told you exactly, but I doubt they were truly "accusing you". They were likely pointing out or alluding to one or more of the things I outlined above. If so, they were correct.
Believe in it! It's absolutely and unequivocally true! Go to any well respected brake manufacturers website and read. I suggest StopTech's site.
Brake pads and rotors need to be properly bedded in (mated to one another). That means an EVEN LAYER of pad material must be deposited on the rotor sufaces. If the brake pad deposit layer is uneven you will experience pedal pulsations and that feeling of "warped rotors".
Write that on the whiteboard as well.
That's a misunderstanding. They are warrantied for street use. NO PRODUCTION CAR is warrantied for track or racing use. None. Not a single one. Racing or other competitive use is not warrantied. Neither is abuse or misuse. That is per your owners manual.
First, they are not "racing brakes". They are simply brakes. Secondly, "How hard is too hard"? It appears you already discovered that. Again, I don't mean to sound sarcastic. I'm telling you the truth. Whether you want to HEAR it or not is up to you.
What to do...
- Go to the site I mentioned and read. Read about proper break-in of pads and rotors. Read about uneven brake pad deposits and what results from it.
- Take it easier on your brakes, especially with new pads and/or rotors.
- Squeeze on your brakes and maintain an even brake pedal pressure. Don't stab at the pedal.
- Try braking sooner. You dont have to wait til you see God to brake (on the street).
Lastly...
You are not driving a race car. As much as you may like to believe that, you're not. Treat it like you would any other car. Yes it is faster. Yes it makes for a better track car, but it is not designed explicitly for that purpose. Disregard what the GM marketing droids may lead you to believe. And yes, much of it is indeed misleading. And yes, they exaggerate. Remember, their job is to SELL cars.
Most importantly...
Your car is not unbreakable, and neither are you.
This is all great and very informative. however, First off, I was NEVER too hard on the brakes. No harder than I have ever broke in a Toyota, Nissan, BMW, Infiniti, etc with NO PROBLEMS. If what you are saying is true... why doesn't every car have brake problems due to in-proper break-in? Let's be realistic here. And secondly, the car IS warrantied to go to a track. call Chevy and ask them. My service writer verified it today. Thirdly, if the brakes were NOT defective, I highly doubt they would of replaced them. I have been preaching Imports and European cars for the last 10 years. It is my own fault for buying another POS American car. They are just pure crap. (although my 1995 Viper never had any brake problems... and I brought it up to the 140-150mph level a few times!) Yes, the Z06 is very fast, but I could never imagine going 150mph+ (let alone 198mph) with these brakes. I would fear for my life. If the car is not made for the track, what justifies the 25-30k extra over a standard C6 coupe? If I was going to have to upgrade EVERYTHING, why not start with the base Vette? None of this makes any sense at all. Its just pure nonsense.
Last edited by jrhunkler : 05-30-2008 at 11:35 PM.
And secondly, the car IS warrantied to go to a track.
I never said it wasn't. I said it was not warrantied for racing ("competition" in the owners manual), abuse or misuse. I also said it was not a race car, and it isn't. When I said "track use" I was referring to the fact they are not going to cover the expected and usual wear and tear associated with such activity.
If you take it to a track and do not engage in racing, or other competition, then it is warrantied. However, it often depends on the individual dealer. They can deny warranty coverage if they determine the car was abused or misused, but that's another debate.
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Thirdly, if the brakes were NOT defective, I highly doubt they would of replaced them.
I agree that the C6 Z06 brakes are not up to the standards they should be. I've always said that. However, track your car and see how often they replace them. After a few track sessions, and your pads and rotors are shot, see how often they replace them under warranty. If you think they should and will continue doing so, you're dreaming.
Believe me, you won't even get them replaced with only street use repeatedly. You can't go in very often and expect them to keep replacing them under warranty for ’warped’ rotors. Blued and/or cracked rotors or rotors with uneven pad deposits are clear signs of abuse or misuse. Brake pad wear is not covered under warranty as it's considered normal wear and tear. I know, some manufacturers cover brake pads for X number of years, along with wiper blades, etc. BMW comes to mind, but Chevrolet is not BMW.
"They are just pure crap." and "I could never imagine going 150mph+ (let alone 198mph) with these brakes. I would fear for my life."
For track use, I agree. Both C5 and C6 Z06 brakes are not as good as some aftermarket brakes. If you're going to go that fast, then you need to use different brake pads as well as different brake fluid (DOT 4) at a minimum. You should also consider additional brake cooling. Even better would be to purchase brakes better suited to that type of driving. Again, the stock brakes are designed for the same purpose as the stock vehicle. That being mainly street use at legal street speeds.
Brake pads have a temperature operating range. If you exceed their max temperature, they will fade. Simply put, you won't have any brakes. At high speeds and especially after repeated use of the brakes, any moisture in the brake fluid will boil and once again, you won't have any brakes. These are all things you have to consider when tracking a car, whether you're racing or not.
You can't take a stock Z06 (or any other car) to a track and expect it to perform perfectly without additional modification for very long. You will go through brakes pads, rotors and tires seemingly almost as fast as you do gas and oil. That's the way it's always been, is now and likely always will be for the foreseeable future at least.
Track preparation is one of the most talked about things on this or any other Corvette forum. In fact, it's one of the main items of discussion on any performance car forum.
The Porsche precedent....
Take the case of the guy with the Porsche GT 2, a car costing close to $200,000. He had the Porsche Composite Ceramic Brakes (PCCB), an option at the time. He took the car to the track and in his words "the rotors turned to sand". He claimed they started to disintegrate after several laps. The dealer refused to warranty them (to the tune of $18,000 at the time) and further stated they would not warranty any car used on a track.
The owner fought them tooth and nail, going through arbitration, the works, and was ultimately refused warranty coverage. In fact, Porsche then changed the language of their U.S. warranty based on that case. It now states they will not warranty their cars for any use other than street use on public roads and highways at or below legal speed limits. I've posted the exact language here before.
The moral of the story...
Given the above example, don't feel bad. At least a Z06 is relatively inexpensive to repair and maintain. If you want to play, you're inevitably going to have to pay. It's that simple.
which rotor[s] is pulsating ? todays rotors are bean counting thin and dont like cutting,if they are cut they tend to warp sooner.30 yrs in autorepair self employed gives me some exp. the most comon form of warping came from uneven lug tightening. eg an owner would come in saying the pedal was pulsating so to make my work easier i grill them on history then usual i get the truth. new tires.flat tire etc. wheels need to be put on cold and lugs tightened with a TQ wrench in a star pattern. i usualy can spot abuse on rotors. no cars are prebroke in. in my c5 the brakes would put my eye balls in the dash. my 07z puts them on the hood. i had a warped rotor on my c5 cuz when i got new tires they tightened the lugs wrong,it shows up after the brakes realy get hot. now days i have an understanding with the GY dealer,they give me a floor jack i roll the tires in one at a time. i let them cool a tad and use a TQ wrench to remove and replace in a star pattern. if ya do your own work put new rotors [oem] and pads [oem] and gently break them in for 500 miles
I never said it wasn't. I said it was not warrantied for racing ("competition" in the owners manual), abuse or misuse. I also said it was not a race car, and it isn't. When I said "track use" I was referring to the fact they are not going to cover the expected and usual wear and tear associated with such activity.
NOT TRUE. IT IS WARRANTIED TO TAKE TO A TRACK.
I'M NOT SAYING THE INDY 500... I'M SAYING A TRACK. A TRACK THAT IS MADE AND IN BUSINESS FOR PEOPLE WHO WANT TO DRIVE FASTER THAN YOU CAN ON THE STREET, AND SAFELY. I THINK CHEVY ENGINEERS KNOW WHEN BUILDING THE 500HP ENGINE THAT YOUR NOT GOING TO TAKE IT TO A TRACK TO DRIVE LEGAL (STREET) SPEEDS. LETS BE REAL HERE GUY.
If you take it to a track and do not engage in racing, or other competition, then it is warrantied. However, it often depends on the individual dealer. They can deny warranty coverage if they determine the car was abused or misused, but that's another debate.
WHY WOULD ANYONE TAKE THEIR CAR TO THE TRACK TO GO 55-60MPH? YOU ARE INCORRECT IN ALL ASPECTS, BUT YOU ARE BRAINWASHED BY YOUR CHEVY DEALER TO THINK OTHERWISE. A Z06 IS MADE FOR THE TRACK. WHAT DON'T YOU GET? THAT DOESN'T MEAN IT IS MADE TO BE DRIVEN ON THE STREETS AT SLOW CAUTIOUS SPEEDS. THAT IS EXACTLY WHY IT "IS" WARRANTIED TO BE TRACKED.
I agree that the C6 Z06 brakes are not up to the standards they should be. I've always said that. However, track your car and see how often they replace them. After a few track sessions, and your pads and rotors are shot, see how often they replace them under warranty. If you think they should and will continue doing so, you're dreaming.
REGARDLESS OF SOME OTHER CARS BEING IMPORTED COSTING MORE MONEY, THIS CAR IS STILL A $75K+ SPORTS CAR BUILT TO BE DRIVEN FAST. $4K BRAKE UPGRADE FROM THE C6 - SO YOU CAN DRIVE IT THE SAME? C'MON MAN!
Believe me, you won't even get them replaced with only street use repeatedly. YOU SHOULDN'T HAVE TO! THATS THE WHOLE F'ING - POINT! You can't go in very often and expect them to keep replacing them under warranty for ’warped’ rotors. Blued and/or cracked rotors or rotors with uneven pad deposits are clear signs of abuse or misuse. THEY WERE NOT BLUE OR CRACKED. DO YOU GET IT YET? THEY WERE DEFECTIVE! Brake pad wear is not covered under warranty as it's considered normal wear and tear. NO KIDDING, REALLY? LOL.I know, some manufacturers cover brake pads for X number of years, along with wiper blades, etc. BMW comes to mind, but "Chevrolet is not BMW"... EXACTLY!
"They are just pure crap." and "I could never imagine going 150mph+ (let alone 198mph) with these brakes. I would fear for my life."
For track use, I agree. Both C5 and C6 Z06 brakes are not as good as some aftermarket brakes. If you're going to go that fast, then you need to use different brake pads as well as different brake fluid (DOT 4) at a minimum. You should also consider additional brake cooling. Even better would be to purchase brakes better suited to that type of driving. Again, the stock brakes are designed for the same purpose as the stock vehicle. That being mainly street use at legal street speeds.
SO BEFORE CHEVY DOES ALL OF THE TESTING THAT THEY DO FOR STAT RECORDS, DO THEY CHANGE THE ROTORS, PADS, AND FLUIDS? OR DO THEY USE THE STOCK EQUIPMENT WHEN THEY REACH 198MPH? I THINK YOUR DELUSIONAL. SOMEBODY DID A VERY GOOD JOB OF SELLING YOU ON THE FACT THAT YOU SHOULD "NEED" TO REPLACE ALL OF THESE ITEMS BEFORE USING YOUR CAR TO DO EXACTLY WHAT ITS BUILT TO DO. YOU DON'T SEE HOW RIDICULOUS THIS SOUNDS?
Brake pads have a temperature operating range. If you exceed their max temperature, they will fade. Simply put, you won't have any brakes. At high speeds and especially after repeated use of the brakes, any moisture in the brake fluid will boil and once again, you won't have any brakes. These are all things you have to consider when tracking a car, whether you're racing or not.
WE'RE NOT TALKING ABOUT BRAKE PADS HERE... DON'T TRY TO UNDERMINE ME! WE'RE TALKING ABOUT BRAND NEW ROTORS BEING WARPED FOR NO JUSTIFIABLE REASON... UNDER "NORMAL" DRIVING CONDITIONS!!!
You can't take a stock Z06 (or any other car) to a track and expect it to perform perfectly without additional modification for very long. You will go through brakes pads, rotors and tires seemingly almost as fast as you do gas and oil. That's the way it's always been, is now and likely always will be for the foreseeable future at least.
THATS FINE, BUT ONCE AGAIN... IN CASE YOU DIDN'T READ WHAT I SAID IN THE BEGINNING... I NEVER TRACKED THE CAR. THE PROBLEM IS UNDER "NORMAL" DRIVING CONDITIONS!
Track preparation is one of the most talked about things on this or any other Corvette forum. In fact, it's one of the main items of discussion on any performance car forum.
The Porsche precedent....
Take the case of the guy with the Porsche GT 2, a car costing close to $200,000. He had the Porsche Composite Ceramic Brakes (PCCB), an option at the time. He took the car to the track and in his words "the rotors turned to sand". He claimed they started to disintegrate after several laps. The dealer refused to warranty them (to the tune of $18,000 at the time) and further stated they would not warranty any car used on a track.
The owner fought them tooth and nail, going through arbitration, the works, and was ultimately refused warranty coverage. In fact, Porsche then changed the language of their U.S. warranty based on that case. It now states they will not warranty their cars for any use other than street use on public roads and highways at or below legal speed limits. I've posted the exact language here before.
A PORSCHE IS JUST AN EXPENSIVE VW. I DON'T CARE FOR THEM, OR THEIR PRODUCTS EITHER WAY. I DEFINITELY WOULD NOT SPEND ANYWHERE NEAR $200K FOR ANY PORSCHE. I DON'T CARE IT FLEW, AND RAN ON WATER.
The moral of the story...
Given the above example, don't feel bad. At least a Z06 is relatively inexpensive to repair and maintain. If you want to play, you're inevitably going to have to pay. It's that simple.
I DIDN'T PAY FOR ALL OF THE UPGRADES THAT COME ON A Z06 SO I WOULD HAVE TO CHANGE THEM, AS IF IT WERE A REGULAR C6, COSTING 30K LESS. WHAT SENSE DOES THAT MAKE?
Last edited by jrhunkler : 05-31-2008 at 11:20 AM.
Let me put it more succinctly: If you take it to a track it is warrantied, unless you engage in competition. It is warrantied unless you abuse or misuse it. Again, per the owners manual.
Note: GM does not tell you what they define as abuse or misuse. Therefore, it's conceivable GM could say "You took it to a track and that is misuse." Go ahead and fight. See how far you get. Are you going to sue GM to force them to fix your car under warranty? Good luck!
If you want answers and suggestions as to how to improve your cars performance, including the brakes, then you have come to the right place. If you want to learn more about how to maintain brakes when used on a track, then again, you have come to the right place.
That said, statements like the following are not going to gain much sympathy here.
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I have been preaching Imports and European cars for the last 10 years. It is my own fault for buying another POS American car. They are just pure crap.
Have you noticed the lack of replies to your original post? Perhaps this is the reason why.
ps: One more thing. In your "Sigh, tired of warped rotors... Advice?" thread you said...
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Originally Posted by jrhunkler
Every time I see your signature i want to break my LCD screen, lmoa
Referring to blkZ06's signature in that way is not going to make you any friends either.
My head hurts from reading this thread, and it reminds me why I seldom visit this forum. I will offer a few comments from a history of a lot of street and track miles on both C5 and C6 ZO6 cars, BMW, and Porsche.
To the OP, don't know what was wrong with your rotors, but I doubt they were warped, which happens only rarely, but is an often used excuse for machining rotors, which is almost always a bad idea. Pad deposits are usually the problem.
The C6 ZO6 has very good brakes, significantly better than the C5. Of course, you need proper track pads for that use; I have had great success with Hawk DTC 70/60 pads. There are a couple of things about the PBR caliper design I don't much like, but the fact is, it works very well. They are better than both the E46 M3 brakes, and at least as good as the Porsche 997 (Brembo) brakes. I brake consistently from 160+ on the VIR back straight with total confidence.
Replacing the C6 Z brakes with a BBK, although popular, is a huge waste of money. Yes, you can get better pad wear from a Brembo or StopTech caliper, primarily because they use the traditional approach of a smaller piston on the leading edge of the pad, which is where the most taper will occur. The C6 ZO6 caliper uses the same size leading piston, so it is relatively harsh on that padlet. On the other hand, it also offers three leading edges per side, as opposed to one, so the braking force is fully as good, or better than many after-market kits. The slightly reduced total pad area is offset by greater torque efficiency, but also more rapid wear.
The car is not a race car. Brakes suitable for race conditions are not found on any production car, and they are not necessary for DE track use.
The car has very good brakes; learn how to use them.
I disagree that this is a headache of a thread, I think it's good info...No one has died or been sued yet...
I have a question. If it's deposits and not true warpage, could you "re-seat" the brakes with some dedicated heat-up and brake runs, or what do you do to get the uneven pad residue off? I would think turning the rotors just a little would be sufficient.
I once had a K5 blazer with literally gouges in the rotor from not replacing the pad (I was a poor student) and I just put new pads on and fought the pull using the power steering for a couple thousand miles and it went away and sort of fixed itself. Not a Z06 technique, mind you, but really, can you just get them really hot and re-seat them if it's just pad residue?
Also, I think drilled rotors warp quicker than non-drilled because they heat up and cool down faster. Most Infinities, BMW's and Camaros don't have drilled rotors that I know of - might I suggest that could be it without a bullet to the head? I think all rotors are pretty much made of the same type of metal if they are indeed metal and not carbon-adamantium-diamond etc etc. I think the C6 Z brakes are sweet on the road at least, but I do notice a little unevenness. I never brake from speed to a stop and sit on the brakes, I always drift at a stop to let the pad move on the rotor...That's my road driving trick, and hey, it's free!!! When I get brake work done. I'll get aftermarket pads. I have Axxis Ultimates on my WRX and it was a night and day difference on that car without servicing the rotors at all, truly.
I have a question. If it's deposits and not true warpage, could you "re-seat" the brakes with some dedicated heat-up and brake runs, or what do you do to get the uneven pad residue off? I would think turning the rotors just a little would be sufficient.
It depends on the combination of pad materials. Street pads following some race pads will not clean them up. Race pad deposits will usually clean off with some cool use. This is why driving home from the track with your track pads is a good idea. It cleans the rotor for the street pads.
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Also, I think drilled rotors warp quicker than non-drilled because they heat up and cool down faster.
Drilled rotors crack quicker, other things equal. Again, rotors seldom warp.
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I think all rotors are pretty much made of the same type of metal if they are indeed metal and not carbon-adamantium-diamond etc etc.
There is a huge difference in the metal compounds used in different rotors. I used a set of Porsche rotors an entire season before replacing. My OE ZO6 rotors are about gone now, with four track days.
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I never brake from speed to a stop and sit on the brakes, I always drift at a stop to let the pad move on the rotor...That's my road driving trick, and hey, it's free!!! When I get brake work done. I'll get aftermarket pads. I have Axxis Ultimates on my WRX and it was a night and day difference on that car without servicing the rotors at all, truly
It is a good idea to cool the brakes as much as possible before stopping with the brakes on. It would probably never happen with street driving, but stopping and sitting with really hot rotors, is one of the few ways you really can warp a rotor. And yes, purpose-specific pads are all the difference. The Ultimates are good street pads, but their fade resistance goes away fast after about 900 degrees, so not a track pad.
elh0102 offers some good advice and I agree with everything he said.
However, I would like to add that you can use an abrasive disc to remove pad deposits on rotors. You're not really removing any metal if done properly, just deposited pad material. It gives the next set of pads a clean surface to bed onto and deposit an even layer of pad material without contamination from previous pad deposits. The caveats being you need to know what abrasive disc to use, what speed and pressure, as well as what pattern, etc.
I only mention this for knowledge sake and it should not be construed as a how-to.
They did replace his rotors, which tells me there was something wrong with them. I would have to agree that this is unacceptable for rotors if the car is only being street driven- and well below any crazy speeds. I think jr is just unhappy because he is saying this happened under normal driving conditions.
As to what causes this is quite simple: You do. Again, I'm not pointing a finger, I'm simply telling you the unbiased truth. Ones braking habits are typically what cause it. There are a number of habits that can lead to uneven pad buildup and I will only state a few... 
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