Front rotors cracked
Thread Starter
Instructor
Joined: Oct 2006
Posts: 176
Likes: 1
Front rotors cracked
I have an '06 C6 Z51 MN6 with 6,500 miles on it. The front rotors have small cracks coming off of every drilled hole in the front rotors, All cracks are about 1/8 inch. 2 cracks per hole. Rear rotors are fine. Any body heard of this happening before? I did do a couple of track days over the last 2 weeks and used my brakes to their limit. All brake parts are stock. I did use RA1 track tires which have far more grip than stock tires.
Safety Car
Joined: Aug 2005
Posts: 4,279
Likes: 82
From: North Strand, NMB, SC; Retired x 2 (US Army: 70-90 AD) (US Army: 91-16 DAC); yea, I'm old.
No Z51 here but IIRC I think I read in previous threads that drilled rotors will develop cracks after being tracked...
Do a search in the archives.
Do a search in the archives.
Safety Car
Joined: Jun 2004
Posts: 3,563
Likes: 2
From: Dallas Tx
Brake pads, rotors, and fluid are consumables at track days. Plan on changing everything after a good day at the track. I'd be surprised if rotors weren't wiped out after a hard track day. Besides pads, rotors, and fluid, consider overhauling the calipers also with new seals. Especially if the brakes got hot enough to boil the fluid and crack the rotors. That much heat cooks the caliper seals.
SOP for a race team after a couple hours of track time is to pitch the pads and rotors and overhaul the calipers. You've got to pay to play.
SOP for a race team after a couple hours of track time is to pitch the pads and rotors and overhaul the calipers. You've got to pay to play.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
I have an '06 C6 Z51 MN6 with 6,500 miles on it. The front rotors have small cracks coming off of every drilled hole in the front rotors, All cracks are about 1/8 inch. 2 cracks per hole. Rear rotors are fine. Any body heard of this happening before? I did do a couple of track days over the last 2 weeks and used my brakes to their limit. All brake parts are stock. I did use RA1 track tires which have far more grip than stock tires.
CF Senior Member
Joined: Feb 2006
Posts: 23,313
Likes: 25
From: Tucson Arizona
From what I've heard this is not uncommon with drilled rotors and the problem isn't necessarily resulting from track use. Accordingly to the Godfather of the C6 (Dave Hill) drilled rotors are 'just for looks.'
I would certainly try to have them replaced under warranty. I wouldn't go so far as to suggest you lie about (not) running the car on a track but I wouldn't mention it unless the subject comes-up either.
I would certainly try to have them replaced under warranty. I wouldn't go so far as to suggest you lie about (not) running the car on a track but I wouldn't mention it unless the subject comes-up either.
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Le Mans Master
Joined: Nov 2004
Posts: 6,566
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From: Goleta CA
Cruise-In VIII Veteran
Mine had cracks just like that, but I just left them for about 6 months because they worked fine. (No track time during those months) Eventully, I replaced them because they warped.
If you go this route, be sure to thoroughly go over the car and pick off all the pieces of rubber. But the look of your tires will probably give it away anyway.
If you go this route, be sure to thoroughly go over the car and pick off all the pieces of rubber. But the look of your tires will probably give it away anyway.
Instructor
Joined: May 2007
Posts: 211
Likes: 0
From: Mountain View CA
Drilled rotors are definitely all aesthetics. The cool air passing through the scorching hot drilled rotors will cause uneven thermal expansion of the metal, causing the stress fractures around the holes....Get yourself some solid rotors 
Instructor
Joined: Aug 2005
Posts: 196
Likes: 0
From: Bethesda MD
Baer
It’s a very common problem. I have a Z-51 and replaced my stock with Baer drilled and slotted. And Hawk pads. Seems like a lot of people on the Forum, when they have rotor problems, go this road. In the end I really don’t care about what it looks like, but as the Baer rotors are lager than stock, it really improved the appearance, to me anyway. It’s really a great set-up and my favorite mod so far. 
Last edited by martinblank; May 30, 2007 at 11:40 PM.
Team Owner
Joined: Aug 2003
Posts: 38,314
Likes: 35
I have an '06 C6 Z51 MN6 with 6,500 miles on it. The front rotors have small cracks coming off of every drilled hole in the front rotors, All cracks are about 1/8 inch. 2 cracks per hole. Rear rotors are fine. Any body heard of this happening before? I did do a couple of track days over the last 2 weeks and used my brakes to their limit. All brake parts are stock. I did use RA1 track tires which have far more grip than stock tires.
Time for new ones if you are going to be tracking the car to the degree that you are.
Team Owner
Joined: Sep 1999
Posts: 20,054
Likes: 44
From: Swansea IL
There's your answer. As other's have said tires and brake components are "consumables" especially when tracked. But your dealer may replace then under warranty, if nothing else you’ll get some new OEM Z51 rotors for use should you sell the car and it records another “rotor failure” to GM who may use that info to make design changes.
I track my C6 Z51 and plan on replacing my OEM Z51 rotor's with the Aussie DBA Series 4000 6X6Wiper-Slot rotors. $650 for all four (shipped). PM me for a source. Take a look - http://www.dba.com.au/2006/products_4000.asp
I saw these in use first hand at Road America this past April. RA is known to be very hard on brakes with its 3 long straights where the Z06's approach 165 MPH. They are wicked good of us weekend warriors.
Tom