I am looking for some information and advice about Z51 front rotors.

My 2006 C6 Z51 just arrived at 20,000 on the odometer. I was in the process of swapping out the brake pads to go to a HPDE track day, which I frequent about twice a year, when I saw small cracks forming on the front rotors. These cracks are extending from just about every drilled hole. So far, the rear rotors appear fine with no cracks visible. These cracks are all less than 1/4" long but a quick look shows they probably won't stay that way.

Given the presence of these cracks I am looking for replacement rotors. I don't think I want to go back to the OE rotors, but it seems finding suitable and supported rotors for Z51 cars is tough. A couple calls to local shops and a quick search of the forums has yet to net enough information to help make an informed decision. Any advice from the knowledgeable folks on the forum is appreciated.

 

Holy shhhnykeys! I was thinking of upgrading my oe non z51s but after seeing this, I might not go the AC delco route.

 

Looks exactly like my Z51 rotors after a few track days. I swapped in some DBA 4000 slotted in the fronts, then the rears when the rears started showing the same cracks. I've got 2 days at Laguna Seca and 2 days at Infineon and they're holding up quite nicely. Darrin has the best prices I've found for DBAs.

http://forums.corvetteforum.com/c6-p...hawk-pads.html

 

. DBA's purchased through Darrin.

 

PM Sent

 

Hold on here. I've heard many people push the panic button on this scenario in the past couple years about cracks in the cross-drilled rotors. At Corvette's@Carlisle, I sat in on a discussion forum which featured (I wish I could remember his name) a top notch tech from the Corvette assembly plant, who was VERY knowledgeable about every bolt and nuance on the Corvette. Some of the questions posed by attendees were focused on these cracks which appear on the cross-drilled rotors, and he elaborated quite a lot of info which was right on target with these concerns. He said that THESE CRACKS ARE PERFECTLY NORMAL WITH ALL THE CROSS DRILLED ROTORS AND ARE NOT AN INDICATION OF A PROBLEM OR NEED FOR REPLACEMENT. Get ready for this 'cause it blew me away: THEY ARE NOT STRESS CRACKS, THEY ARE HEAT CRACKS AND ARE PERFECTLY NORMAL EVEN THOUGH THEY MAY RUN FROM ONE HOLE TO ANOTHER SO LONG AS THE CRACK IS NO LONGER THAN 1 1/4" LONG AND DO NOT EXTEND TO THE OUTER CIRCUMFRENCE OF THE ROTOR. So, my friends, do not panic and do not claim shabby materials or design flaw. If you call GM factory and speak with any knowledgeable tech there, they will verify this. Let put this issue to sleep and save your money for other more deserving attention. There are thousands of rotors being scrapped by unknowing owners thinking that they are bad or defective when this is clearly not the case.

 

I have the two piece slotted rotors from performanceafx for the front and rear. They are great rotors at a good price.

 

I'm sure you've seen it elsewhere, but on the off chance that you haven't, a lot of track-day regulars swap to the non-z51 abutments and run the cheap and durable slotted, but non drilled NAPA rotors.

Here's a good thread with part numbers and opinions.

-Scott

 

Yes, some cracking on the Z51 rotors is pretty normal. Do a search and you'll come up with more info. There may be a TSB on this issue as well. If Talon90 is on-line he might chime in.

 

Just to close this thread out, I ended up at a dealer after the track day ended and they yanked off the original Z51 rotors and found cracks that went from hole to hole on the back-side of both front rotors. According to the service writer, cracks that large are grounds for replacement and rotors are listed as "consumables" by GM and thus not covered under warranty... not that I expected they would be.

Given my light driving of this car I opted for them to put on another pair of OE Z51 rotors for now. I'm sure I will go aftermarket at some point but at $100 a side it was cheaper to go this route for now. Thanks for all the input as I'm sure I'll need it again in the future.