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      03-29-2012, 09:35 AM   #23
CanAutM3
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Quote:
Originally Posted by LiM3y View Post
I am surprised there are not more posts about warped rotors at the track based on the discussion here. I am also surprised that the rear rotors needed replacing at the same time as the fronts with the M3's brake balance.

Since switching to race pads, and going through a set of Hawk DTC-70's in five track days, I haven't had any of the symptoms of shudder under braking associated with either pad deposit with OEM pads or warped rotors. However I did have front rotors replaced due to small cracks forming at the venting holes. Using race pads, the kinetic energy dispersion and temperatures are the same (kinetic energy is higher by v^2) as using OEM. If the rotors were warping under these conditions, wouldn't the problem get worse with better pads?
Agree on your warping point . Using a more track oriented pad will definitely reduce, if not eliminate bad pad transfer.

Question though, how bad were the cracks in your discs?

Cracks appearing on cross drilled rotors is fairly normal when used at the track. As long as the cracks don't stretch from one hole to another, or worse from a hole to the outside edge of the disc, the discs should be perfectly safe to use.

I had cracks appear right after the first couple of track days with the car. Kept the discs for three and half seasons (at 12-15 track days per season). I eventually had to replace them because I had worn down the thickness of the discs. No warping or cracks connecting the holes. Stock discs are pretty sturdy. I use crappy Hawk HP+ pads, cheap and better than stock but definitely not the best out there.

Same experience with my E46 BTW (I was running EU spec cross drilled discs).
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      03-29-2012, 10:08 AM   #24
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Quote:
Originally Posted by CanAutM3 View Post
Agree on your warping point . Using a more track oriented pad will definitely reduce, if not eliminate bad pad transfer.

Question though, how bad were the cracks in your discs?

Cracks appearing on cross drilled rotors is fairly normal when used at the track. As long as the cracks don't stretch from one hole to another, or worse from a hole to the outside edge of the disc, the discs should be perfectly safe to use.

I had cracks appear right after the first couple of track days with the car. Kept the discs for three and half seasons (at 12-15 track days per season). I eventually had to replace them because I had worn down the thickness of the discs. No warping or cracks connecting the holes. Stock discs are pretty sturdy. I use crappy Hawk HP+ pads, cheap and better than stock but definitely not the best out there.

Same experience with my E46 BTW (I was running EU spec cross drilled discs).
I might have used this as an excuse to get new rotors prior to warranty expiry.

I had my front rotors replaced at 19K and ~45K. My rear rotors at ~50K just before warranty expired. I drive my M3 DD year round. I am "just about" to hook up some DIY brake ducts similar to those descibed elsewhere on the board. I am eating brake pads at the moment. I have two options - better heat management, or as my instructor buddy pointed out, brake less!
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      03-29-2012, 10:56 AM   #25
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Are you guys getting pinging sounds while the rotors cool after just normal street driving?
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      03-29-2012, 11:48 AM   #26
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Are you guys getting pinging sounds while the rotors cool after just normal street driving?
The car makes crazy popcorn noises after a track session . This is due to the Aluminum/Steel interface on the rotors (both material do not have the same heat expansion characteristics). Don't worry, this is normal . It is usually not as prominent after street driving though, unless I was out for a joy ride .
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      03-29-2012, 11:52 AM   #27
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Quote:
Originally Posted by LiM3y View Post
I have two options - better heat management, or as my instructor buddy pointed out, brake less!
I like that second option
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      03-29-2012, 04:46 PM   #28
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Quote:
Originally Posted by LiM3y View Post
I have two options - better heat management, or as my instructor buddy pointed out, brake less!
Or as my track buddy always likes to say, "brakes are overrated, they just slow you down". Obviously, I don't subscribe to that theory, as I've gone through virtually the same progession as most of you with my R32 (also brake ductless), until finally giving up, and buying an ST-40 for this track season.
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      03-30-2012, 07:25 AM   #29
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When I used to drive on the Ring with the stock brakes/pads, I used to coast down the straight and exit out into the town of Nurburg down to the BMW M Test Center and back up to the parking lot. This is to help cool the brakes but it sure as hell didn't help. The PFC BBK w/ PF01 pads I have up front now is incredible, I run the car around the parking lot at VIR once for my cool down and then back to my parking spot. No issues.

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      03-31-2012, 11:54 AM   #30
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Quote:
Originally Posted by CanAutM3 View Post
If the deposit is severe, it can take more than 2 weeks of street driving to remove.
I seem to get pad buildup with my street pads (Carbotech Bobcat), during the winter. I've found that low speed stops, especially when the rotors are wet, has been the best way (other than bedding) to get rid of pad deposits.

The pads are ceramic - not sure if that makes any difference.
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      04-02-2012, 03:40 PM   #31
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Great find!
For anyone interested, here's some VIR of my cousin's hubby in his 911 GT3 with mods and M5:
http://www.youtube.com/user/TrackdayDriver
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