Dan H.

Good morning all,
I'm not certain how I tell when its time to replace rotors. My car has done 2 days at summit point and 3 days at watkins glen. I bought my car this spring ('02 Z06) with 16k miles with all OEM running gear.

I ran the two days at summit with the OEM pads and used them up quickly. I bought a full set of Hawk HP+ pads for the three day glen event. I used most of these up as well. I glazed the rotors pretty good as well.

Now I'm getting my list together to prep for a single day event at lime rock. I'm gonna pick up some carbotech pads, but the rotors are a mystery to me. They don't pulse at all. They still have that pad glaze on them. I decided I'll get the centric disposable rotors when its time to change them.

I could use your help on what the signal or trigger is to change the rotors. Your help is appreciated.

StKnoWhere

General rule of thumb is rotors are usable until they develop cracks big enough to catch your fingernail and into the edge of the rotor.

I would replace the rotors and put the stock on the shelf to put back on when you sell the car. I like DBA but many who are better drivers seem to prefer NAPA or Centric blanks.

Otherwise, be aware the Carbotech compound can be incompatible with other compounds. You can try driving with the Hawks on the street (occasionally drag the brakes, gentle low speed stops, don't get them hot) and see if that will clean the rotors to where they are nice and shiny.

Or, they can be sanded with a disk or turned to get back to bare metal.

You have an awsome, fun car for the track - enjoy!

Hat_Trick_Hokie

ZedO6

I'm not sure how many C5 track cars get PM for rotors after a given amount of sessions or when the cracks get "too big" and how many of us just wait for the telltale thumping of a cracked rotor and replace them at the track. I've done it both ways.

In the example below, the non-fatal cracks surrounding the failure were not that bad and I've run rotors in that condition for multiple sessions. In fact most of my take off "spares" fall into this condition category. I try to avoid using brand new "green" rotors on the track without at least one heat cycle on the street, so I pull "broken in" front rotor pairs and bring them to the track for my spares and put new uncycled rotors on my car for the drive to the track. Not sure if anyone has empirical data on these failures to validate any of this. BTW, I've found no difference between GM rotors (pictured here) and quality aftermarket, they all suck.

crimlwC6

Buy a set of the centrics now and take them to the track along with the necessary tools to swap out or go ahead and do it now and bring the old ones just in case. $80 is cheap insurance to not ruin a $500 registration fee. Be sure to try and drive around for a full cool lap or drive around after the session. The change in temp is what will crack a rotor.

Dan H.

Thanks for the advice guys

Supercharged111

I too just wait for the thump, but I don't cut my session short for it. Get 'em hot and they'll smooth right out. Mine always crack back in the pits. It's a matter of when, not if, even with a cool down lap. I always try my best not to touch the brake pedal on the cool down lap, but maintain a decent pace to keep air flowing through the rotors.

ZedO6

I've gone out with the thump from a cracked rotor and a couple of turns later the rotor heats up and the crack closes up and braking is smooth again. I also agree, they seem to crack through after they cool down.

SouthernSon

The advantage of the two pc. that floats on the hat lies in the fact that the rotor mass is all in the same plane as it cools whereas the 1 pc. rotor deflects on the face since the hat portion is all one piece and deflects toward the mass of the hat. I wish I could explain that better but I think you see the point. I use 2pc. but carry oem back up rotors if needed while at the track since it takes a while to change the rotor on the hat of 2pc. Once the crack makes it to the edge of the 2pc. you must replace - they sometimes simply explode at that point. As said, the 1 pc. rotor crack will simply come back into plane once brought up to temperature. I, too, have run many 1 pc. past the thump during a session.

StKnoWhere

even better idea

I cracked one at the track backing in to a garage when someone walked behind me and I held the brake peddle down too long on hot rotors. I pull in head first now.