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!
Not sure about the US, but here in Switzerland forget the showroom to track claim.
You would only feel a "flutter" while braking, not just over 70 MPH. Pressing the break pedal on warped disks will give an instant flutter and brake pedal push back - but only while actually braking. (I have driven my car to 173 MPH with warped disks.) The problem is then finding the "threshold" for braking as yoou can no longer feel the pedal pressure correctly - they still stop the car!
New rotors always need bedding. I took my Z06 to the track after 5000 KMS and still managed to warp the disks!
machining out the warp is NEVER a good idea. (Less metal, uneven thickness resulting in hot spots and new warp!)
I have changed to dba and Hawk pads, and so far so good - with better braking (which was the point).
I think you will find that the front disks are in fact "sensitive" to the point where I was wondering if during winter, when my car was new, and I was "playing" (Read learning to keep the beast in a straight line on cold and wet roads) the Traction control "snapped" onto the disks hard when the rear end got out of line. On cold and new disks and at reasonable speeds, that is more than enough to do the damage.
Anyway - A number of members have found that changing rotors to another mark has improved braking - endurance etc. Not too expensive either - (Shipped to Switzerland I got a great price)
WARNING: Drilled rotors with cracks. CHANGE THEM ASAP. I saw a car come off fast at Dijon with that one, both disks failed at the same time on track. Go for solid slotted multi piece rotors. IMHO
__________________
Move over Mansell:
"Racing is life ... everything else is just waiting.", Steve McQueen
the only issue you answered ya didnt answer,an e mail from the dealer doesnt mean the lugs were tightened properly
I'm not sure I understand your reply. He is saying it is impossible for them to be tightened too much (or incorrectly as he stated to be over the phone)?
I'm not sure I understand your reply. He is saying it is impossible for them to be tightened too much (or incorrectly as he stated to be over the phone)?
i,m asking you specific things. eg. are the lugs tightened right and your reply was dealer info. [i am not being a wise guy or breaking your chops] if you work on your car and have the tools [torque wrench,dial indicator] check things,dont take someones word. 30 years selfemployed auto repair so ive got some wrench time. when pulsating brake pedal jobs came in the best tool was grilling the owner. many times they led me to the wheel/rotor that was the issue. at times you had to go to the rear brakes to fix the front brakes .eg the rear pads are glazed and making the fronts work too hard and warping rotors. this is where you need an infared probe.very common problem was they had tire/tires changed and the pulsating started shortly after. to diagnose this you use a torque wrench to loosen the lugs to see how tight each one is.i,m not telling you this is going to fix your car but to diagnose things you MUST check the basic things. my reply is you dont know if the lugs are/where tightened correctly because you are taking someones word.again i,m not giving you are hard time,im trying to help but i must have hard data not assumptions. do you have the tools for checking these things ?
i,m asking you specific things. eg. are the lugs tightened right and your reply was dealer info. [i am not being a wise guy or breaking your chops] if you work on your car and have the tools [torque wrench,dial indicator] check things,dont take someones word. 30 years selfemployed auto repair so ive got some wrench time. when pulsating brake pedal jobs came in the best tool was grilling the owner. many times they led me to the wheel/rotor that was the issue. at times you had to go to the rear brakes to fix the front brakes .eg the rear pads are glazed and making the fronts work too hard and warping rotors. this is where you need an infared probe.very common problem was they had tire/tires changed and the pulsating started shortly after. to diagnose this you use a torque wrench to loosen the lugs to see how tight each one is.i,m not telling you this is going to fix your car but to diagnose things you MUST check the basic things. my reply is you dont know if the lugs are/where tightened correctly because you are taking someones word.again i,m not giving you are hard time,im trying to help but i must have hard data not assumptions. do you have the tools for checking these things ?
I'm not saying I understand anything about brakes, but I do want to tell you my "showroom to track" experience:
My car was bought new and driven home from the NCM. I just tracked it at 3800 miles on nothing but a oil change. Before the track, it did as was posted here: an uneven brake shutter while driving on the street - but it did seem to be not an issue when driven hard. I assumed it was the symptoms of a high performance car driven on the street...That is, I just needed to do an "italian tune up"...
I even prepped it for the track by trying some repetitive stops from 70. Seemed just fine, then.
I did about 275 miles on the track at a HPDE event. Now, surprise: The brakes are perfect. Slow even braking gives no shutter, hard braking is fine.
This seems to back up the position that uneven brake pad residue was on the rotors and I effectively cleaned them with many laps at speed. It seemed to me that some serious braking would clean this up, and it seemed to be the case.
I did notice that the high speed braking at one point in the afternoon did give some unevenness (155mph to 120), but this too even passed. I'll let you know when I try again with the same set up but for a brake fluid change. (stock 08 Z).
I experienced no brake fade all day, with many 45 minute track runs. Now,granted, one person's track driving is not the same as another's. But my first impression is this: These brakes are track ready, and I'm ready to brake with them at 155 into a turn with nothing more than a fluid change. I think that says a lot.
I'm not trying to dis anyone, I'm just giving my experience.
I'm thinking after all of this nonsense, it just may be pad deposits? What's the best way to remove them? Drive hard for a little while? I actually baby my brakes, because I never want to get too much dust on my black rims! lol...
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!
Just keep a smile on your face, write up a detailed spec for them to inform and follow regarding the cars problems. They will keep replacing parts until they get it right. If the service manager at the dealership is an "A" hole ask him for the regional managers address and phone number. Main thing is be cool. After decades of owning these cars I found most all dealerships corvette and customer friendly and just two totally out of line. Just keep taking it back to them it's their job to fix it. FYI, you shouldn't have to explain to them how you drive the car either . Brakes are a safety issue .
JR, I don't get your two last posts, they seem to conflict each other. You may want to clarify?
If you trust your car, do a HPDE, you can use the excuse that it's to brake in the brakes.
All I can add to this is that I tried to get rid of the slight shudder I had from nearly new by doing about 8 70-0 hard stops in a row. It didn't change anything. As I said above, though, I really didn't feel the mild shudder when I got on them, so I figured it was a nuisance, not a safety issue.
But after tracking my car was the first time the shudder was gone. I haven't driven it in a while, but if it comes back, I'll repost. I don't want to mislead anyone if I was wishful thinking.
My guess is, you have to really wear the brakes at temp to effect any change... In my totally novice and amateur opinion. Good luck.
JR, I don't get your two last posts, they seem to conflict each other. You may want to clarify?
If you trust your car, do a HPDE, you can use the excuse that it's to brake in the brakes.
All I can add to this is that I tried to get rid of the slight shudder I had from nearly new by doing about 8 70-0 hard stops in a row. It didn't change anything. As I said above, though, I really didn't feel the mild shudder when I got on them, so I figured it was a nuisance, not a safety issue.
But after tracking my car was the first time the shudder was gone. I haven't driven it in a while, but if it comes back, I'll repost. I don't want to mislead anyone if I was wishful thinking.
My guess is, you have to really wear the brakes at temp to effect any change... In my totally novice and amateur opinion. Good luck.
I could see how they could "seem" conflicting... what I meant was, because I'm always conscience of getting my rims dirty, I tend to step on the brakes in short small jabs, rather then brake long and continuous... I try to keep the pad away from the rotor as much as possible. They seem to be ok, unless I'm hard on them, which still is not right at all.
......All I can add to this is that I tried to get rid of the slight shudder I had from nearly new by doing about 8 70-0 hard stops in a row. It didn't change anything. As I said above, though, I really didn't feel the mild shudder when I got on them, so I figured it was a nuisance, not a safety issue.
But after tracking my car was the first time the shudder was gone. I haven't driven it in a while, but if it comes back, I'll repost. I don't want to mislead anyone if I was wishful thinking.
My guess is, you have to really wear the brakes at temp to effect any change... In my totally novice and amateur opinion. Good luck.
First of all - whenever you're bedding new pads and/or rotors, DON'T come to a complete STOP. You may very well do a "pad imprint" on the hot rotor and you'll get the flutter and brake pedal pulsations JR is talking about.
It's very difficult to warp modern rotors, and most all cases of a pulsating pedal are uneven transfer of pad material to the rotor. After a track session you want to try to avoid coming to a complete stop with the brakes in stationary contact with the hot rotors - when I come into the paddock area I try to pretty much coast to a stop, and I never set the parking brake - just shut it down and leave it in gear. Likewise, if you've been braking hard during street driving and come to a stop and hold position at a light with the brakes on, pushing the pads down on the hot rotors, you may get a pad imprint that will give you the pulsating pedal.
Second - I believe you're correct that the best way to "clean" the rotors of uneven pad buildup is to use the brakes hard, as you did at the track.
And this same issue is a HUGE issue for all the import cars that use ceramic based pads. They are even worse at maintaining a nice transfer layer.
Your rotors are thick and huge - yes the drills are dumb - and it was prettylame to make only one curved vane rotor -
But the weak link is the pads. When hot - and w/ your foot on brake - it will imprint on the rotor.
Just like this although it's not always visible
It can be avoided by being aware of the circumstances that cause it -
(whatever you did to cause it - you did it again)
It can often be fixed by:
Rebedding pads aggressively
Sanding the rotors (that's what I did to those and they are now perfect)
Turning them (which removes the 0.000x ion. of bad transfer layer and 0.00x in. of cast ironl that helps you stop.
Rotor runout is sometimes the case - especially w/ cheap chinese rotors that are so inconsistent - but a poor transfer layer is most commonly the cause. For some reason we (America?) just cut rotors all day - send the customer out without telling or really knowing why i thappened -and then see them back in 3-6 months when it happens again.
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