Crack in Stock Rotor... is this still safe or are they toast?

SpiralOut · 05-09-2013, 08:53 AM

This is a new car only a few months old, have just 2 track days on it and yesterday I see cracks like this in both front rotors and they seem to be shallow cracks but they go all the way across the face. I'm wondering what people think..... is this safe for additional track events or should these be trashed? I've been tracking for a while so I'm in advanced run groups and I'm pretty tough on brakes.

My setup is 275/35-18 Toyo R888's, SS lines, Carbotech XP20 Front/XP10 Rear, and I do have the Cantrell ducting system installed and use it for both events I've been to.

I had major issues with cracking/warping front rotors in my 335i and I was kinda hoping the better rotor design in the M3 and adding the ducting would help but apparently not.

Is looking like a BBK may be my only option to really fix/avoid this issues. Due to high costs of the BBK's I was trying to not go that route if i didn't have to.

warp10 · 05-09-2013, 09:04 AM

can you feel the crack with your nail? bc to me this looks more this pad deposits, but that just me.

Gearhead999s · 05-09-2013, 09:10 AM

Are you sure that is a crack?Looks like the pad imprinted on the rotor and left some pad material.If it is a crack(which I doubt)junk the rotor for sure.

SpiralOut · 05-09-2013, 09:18 AM

I do need to scrub those deposits off and that will give me a better view, just went to track this weekend and have been very busy so didn't clean em off like i usually do. Hopefully you're right and it's not a crack. Just seemeed weird it was all the way across and it did seem like i could feel it with my fingernail. But I could just be being paranoid after my previous bad experiences though.

MilehighM3 · 05-09-2013, 09:53 PM

That's a crack for sure. When in doubt, change them out is what I say. Brakes are to important to let something questionable pass.

Porschefile · 05-09-2013, 10:21 PM

If you can't catch your nail on it it isn't anything to worry about IMO. That rotor doesn't look that bad.

Vic311 · 05-09-2013, 10:26 PM

The nail theory doesn't apply here, sometimes stress fractures are not even visible to the naked eye and have to be examined under magnification. And under further heat cycles (expansion/contraction) you could have a serious failure.

OP I would replace them, these are your brakes, why take a chance?

r53s65e90 · 05-10-2013, 12:21 AM

This 100% a crack. Too radial to be a deposit from the edge of the pad. If it were from the center grove there would be a pair of imprints.

Rotor is gone for sure.

R-compounds and high temps should be to blame along with a probably not so good batch of rotors, which would be otherwise fine for street.

If you are still under warranty, it should be covered. Track pads ate supposed to work with this car.

S65V8 · 05-10-2013, 06:52 AM

so much for the brake ducting, should of helped. two track events, yikes, it usually took almost a full season for me to wear down a stock set of front rotors.

DR-JEKL · 05-10-2013, 07:18 AM

I'm not convinced that's a crack, as when you look at the glazed area of the rotor you cannot see the continuation of what one would perceive as being a crack.

Perhaps do a simple dye check, or even just rub some coarse emery paper on the area to see if it is still remaining once you rub the affected area.

P.S I'm a metallurgical engineer working in the rolling stock/rail industry and see crack defects quite often, so I would like to think my comment carries some merit

apecush · 05-10-2013, 09:13 AM

Quote:

Originally Posted by DR-JEKL

P.S I'm a metallurgical engineer working in the rolling stock/rail industry and see crack defects quite often, so I would like to think my comment carries some merit

Wow, not everyday I run into another (metE that is...)

For what it's worth, 99.9999% of the time, cracks don't run in a straight line, that's just not how the world works. Further to dr-jekl's comment, you can pick up a dye penetrant kit from your local industrial supply house for under $50, and you should be able to find instructions online on how to use it. Cheaper than a new rotor, and you get a definitive answer on your suspected crack.

DallasBoosted · 05-10-2013, 01:35 PM

Looks like a crack to me.

ThunderMoose · 05-10-2013, 06:42 PM

Looks like deposits to me. I had something similar on rear rotor. It was too linear to be a crack and matched perfectly angle wise with edge of pad. I had a lot of heat stress cracking on front rotors and it was a lot smaller indications.

MilehighM3 · 05-10-2013, 07:57 PM

Quote:

Originally Posted by ThunderMoose

Looks like deposits to me. I had something similar on rear rotor. It was too linear to be a crack and matched perfectly angle wise with edge of pad. I had a lot of heat stress cracking on front rotors and it was a lot smaller indications.

I've yet to see a pad that makes contact completely across the contact area in that straight of a line. The pads leading and trailing edges are chamfered and the pads are wider/longer at the top edge than they are on the inner edge.

1MOREMOD · 05-10-2013, 08:05 PM

Quote:

Originally Posted by Bmw135er

I've yet to see a pad that makes contact completely across the contact area in that straight of a line. The pads leading and trailing edges are chamfered and the pads are wider/longer at the top edge than they are on the inner edge.

+1 but also doesn't look like a crack. Hard to tell though from pictures.

bigjae1976 · 05-13-2013, 01:49 AM

That looks like pad deposits. Why would a crack NOT start at one of the holes...which would be the weakest part of the rotor? BTW, there's an internal vain that runs behind that line so I highly doubt that's a crack.

TXmtrhed · 05-13-2013, 07:11 AM

Looks just like a pad deposit I noticed on my rear rotor I while washing my car this weekend. Go out and stomp on the brakes and see if it goes away.

1MOREMOD · 05-13-2013, 09:44 AM

what type of pads have a square edge like that?

S65 · 05-13-2013, 10:35 AM

Warranty will cover it.

apecush · 05-15-2013, 12:42 PM

Quote:

Originally Posted by 1MOREMOD

what type of pads have a square edge like that?

not edge, but channel at the centre of the pad...

The stock pads certainly do, not sure about the carbotechs

sawzall · 05-15-2013, 02:49 PM

Carbotechs are known to be pretty harsh on rotors. That being said, given your setup, you probably want to look for a good set of OEM replacement slotted rotors. If you find you don't have enough heat capacity, only then look at moving up to a BBK.

SpiralOut · 05-15-2013, 03:02 PM

Hey guys, I was out of town for a while so just getting back to this. Anyway, I did bed the OEM pads in really good yesterday to clean the rotors off and I think this line was indeed just a pad deposit. It is still there but you can just barely see it now and you cannot feel it with a thumbnail.

Someone up above made a good point.... the crack would more than likely start in a hole and not all the way across the solid part of the rotor. I tried some Racing Brake replacement rotors on my 335i a couple years ago and they always started cracking around the holes first. Long story there, but I will never buy racing brake products again.

I am pretty sure I'm going the BBK route. On track day my biggest issue/worry is brakes and if I could not have to worry about them so much and make pad changes quicker (with the stoptechs) then the $$ will be worth it in the long run. I'm starting to save some $$ now and looking for the best deal on the stoptechs. Hopefully sometime this summer I can get em.

05-09-2013, 08:53 AM	#1
SpiralOut Captain 148 Rep 880 Posts Drives: 2022 X5Mc Join Date: Nov 2006 Location: NC iTrader: (11)	Crack in Stock Rotor... is this still safe or are they toast? This is a new car only a few months old, have just 2 track days on it and yesterday I see cracks like this in both front rotors and they seem to be shallow cracks but they go all the way across the face. I'm wondering what people think..... is this safe for additional track events or should these be trashed? I've been tracking for a while so I'm in advanced run groups and I'm pretty tough on brakes. My setup is 275/35-18 Toyo R888's, SS lines, Carbotech XP20 Front/XP10 Rear, and I do have the Cantrell ducting system installed and use it for both events I've been to. I had major issues with cracking/warping front rotors in my 335i and I was kinda hoping the better rotor design in the M3 and adding the ducting would help but apparently not. Is looking like a BBK may be my only option to really fix/avoid this issues. Due to high costs of the BBK's I was trying to not go that route if i didn't have to. Attached Images
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05-09-2013, 09:04 AM	#2
warp10 Lieutenant Colonel 776 Rep 1,718 Posts Drives: 2011 M3 Jet Black:ZCP, ZCV, ZP Join Date: May 2011 Location: Atlanta, Ga iTrader: (7) Garage List 2011 M3 [10.00] 2011 28i X3 [0.00]	can you feel the crack with your nail? bc to me this looks more this pad deposits, but that just me.
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05-09-2013, 09:10 AM	#3
Gearhead999s Major General 819 Rep 7,887 Posts Drives: RR Velar R=Dynamic M2C R1200GS Join Date: Apr 2007 Location: Toronto iTrader: (0)	Are you sure that is a crack?Looks like the pad imprinted on the rotor and left some pad material.If it is a crack(which I doubt)junk the rotor for sure.
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05-09-2013, 09:18 AM	#4
SpiralOut Captain 148 Rep 880 Posts Drives: 2022 X5Mc Join Date: Nov 2006 Location: NC iTrader: (11)	I do need to scrub those deposits off and that will give me a better view, just went to track this weekend and have been very busy so didn't clean em off like i usually do. Hopefully you're right and it's not a crack. Just seemeed weird it was all the way across and it did seem like i could feel it with my fingernail. But I could just be being paranoid after my previous bad experiences though.
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05-09-2013, 09:53 PM	#5
MilehighM3 Brigadier General 915 Rep 3,456 Posts Drives: Harrop E90 M3 Join Date: May 2011 Location: Colorado Springs iTrader: (14) Garage List 2009 E90 M3 [6.50]	That's a crack for sure. When in doubt, change them out is what I say. Brakes are to important to let something questionable pass.
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05-09-2013, 10:21 PM	#6
Porschefile Major 59 Rep 1,250 Posts Drives: E92 M3 Join Date: Jul 2008 Location: Tennessee iTrader: (7)	If you can't catch your nail on it it isn't anything to worry about IMO. That rotor doesn't look that bad.
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05-09-2013, 10:26 PM	#7
Vic311 Banned 42 Rep 1,463 Posts Drives: 2011 e92 M3 Join Date: Dec 2012 Location: NY iTrader: (0)	The nail theory doesn't apply here, sometimes stress fractures are not even visible to the naked eye and have to be examined under magnification. And under further heat cycles (expansion/contraction) you could have a serious failure. OP I would replace them, these are your brakes, why take a chance?
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05-10-2013, 12:21 AM	#8
r53s65e90 8300 19 Rep 573 Posts Drives: r53 s65e90 Join Date: Mar 2009 Location: San Jose, CA iTrader: (0)	This 100% a crack. Too radial to be a deposit from the edge of the pad. If it were from the center grove there would be a pair of imprints. Rotor is gone for sure. R-compounds and high temps should be to blame along with a probably not so good batch of rotors, which would be otherwise fine for street. If you are still under warranty, it should be covered. Track pads ate supposed to work with this car.
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05-10-2013, 06:52 AM	#9
S65V8 _ 812 Rep 3,160 Posts Drives: ... Join Date: Apr 2009 Location: Los Angeles, CA iTrader: (10)	so much for the brake ducting, should of helped. two track events, yikes, it usually took almost a full season for me to wear down a stock set of front rotors.
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05-10-2013, 07:18 AM	#10
DR-JEKL Major General 900 Rep 6,285 Posts Drives: Space Grey E92 335i 6MT Join Date: Jul 2012 Location: Newcastle Ozstraylia iTrader: (3)	I'm not convinced that's a crack, as when you look at the glazed area of the rotor you cannot see the continuation of what one would perceive as being a crack. Perhaps do a simple dye check, or even just rub some coarse emery paper on the area to see if it is still remaining once you rub the affected area. P.S I'm a metallurgical engineer working in the rolling stock/rail industry and see crack defects quite often, so I would like to think my comment carries some merit
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05-10-2013, 01:35 PM	#12
DallasBoosted Captain 38 Rep 864 Posts Drives: '08 E92 335i Join Date: Apr 2012 Location: Dallas iTrader: (3) Garage List 2008 BMW 335i [10.00]	Looks like a crack to me.
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05-10-2013, 06:42 PM	#13
ThunderMoose Lieutenant Colonel 746 Rep 1,848 Posts Drives: PY E46 M3 and SG E46 M3 Join Date: Aug 2010 Location: League City, TX iTrader: (0)	Looks like deposits to me. I had something similar on rear rotor. It was too linear to be a crack and matched perfectly angle wise with edge of pad. I had a lot of heat stress cracking on front rotors and it was a lot smaller indications.
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05-13-2013, 01:49 AM	#16
bigjae1976 Major General 1581 Rep 8,077 Posts Drives: 11 E90 M3 Individual Join Date: Mar 2006 Location: Houston, TX iTrader: (22) Garage List 2004 BMW M3 [4.50] 2011 BMW E90 M3 [5.25] 2013 BMW 328i [5.00]	That looks like pad deposits. Why would a crack NOT start at one of the holes...which would be the weakest part of the rotor? BTW, there's an internal vain that runs behind that line so I highly doubt that's a crack. __________________ 2018 F30 320iX Melbourne Red 2011 E90 M3 Monte Carlo Blue 2004 E46 M3 Imola Red 2000 E36/7 Z3 Steel Blue
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05-13-2013, 07:11 AM	#17
TXmtrhed First Lieutenant 37 Rep 381 Posts Drives: VO 1M Join Date: Aug 2010 Location: Katy, TX iTrader: (0)	Looks just like a pad deposit I noticed on my rear rotor I while washing my car this weekend. Go out and stomp on the brakes and see if it goes away.
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05-13-2013, 09:44 AM	#18
1MOREMOD - 11818 Rep 23,187 Posts Drives: Race car-> Join Date: Mar 2009 Location: check your mirrors iTrader: (5)	what type of pads have a square edge like that? __________________ 02 Tiag e46 M3\|6MT\|GC plates\|MCS c.o.\|GC bars\|GC race control arms\|GC bushings\|BW eng. & tran. mounts\|subframe kit\|BW race shifter\|BW Jaffster\|Euro header\|BW exhaust\|K&N c.a.i.\|Epic race tune\|Rouge pulleys\|Seibon CF hood\|CSL bumper\|apr gt 250 & splitter\|ST-40\|XR-2\|SS lines\|half cage\|Recaro profi\|Profi 2 harness\|BMWpedals\|BW studs\|
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05-13-2013, 10:35 AM	#19
S65 Private 5 Rep 73 Posts Drives: E92 m3 Join Date: Mar 2013 Location: Valencia iTrader: (0)	Warranty will cover it.
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05-15-2013, 02:49 PM	#21
sawzall Major 50 Rep 1,285 Posts Drives: A Car Join Date: May 2010 Location: Toronto iTrader: (0) Garage List 2012 911S [10.00] 2011 911 GT3 RS [0.00]	Carbotechs are known to be pretty harsh on rotors. That being said, given your setup, you probably want to look for a good set of OEM replacement slotted rotors. If you find you don't have enough heat capacity, only then look at moving up to a BBK.
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05-15-2013, 03:02 PM	#22
SpiralOut Captain 148 Rep 880 Posts Drives: 2022 X5Mc Join Date: Nov 2006 Location: NC iTrader: (11)	Hey guys, I was out of town for a while so just getting back to this. Anyway, I did bed the OEM pads in really good yesterday to clean the rotors off and I think this line was indeed just a pad deposit. It is still there but you can just barely see it now and you cannot feel it with a thumbnail. Someone up above made a good point.... the crack would more than likely start in a hole and not all the way across the solid part of the rotor. I tried some Racing Brake replacement rotors on my 335i a couple years ago and they always started cracking around the holes first. Long story there, but I will never buy racing brake products again. I am pretty sure I'm going the BBK route. On track day my biggest issue/worry is brakes and if I could not have to worry about them so much and make pad changes quicker (with the stoptechs) then the $$ will be worth it in the long run. I'm starting to save some $$ now and looking for the best deal on the stoptechs. Hopefully sometime this summer I can get em.
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