Gary R.

Curious, on the high quality rotors, are they cast or drilled holes?

Steve Weiner-Rennsport Systems

They are cast, but the REAL difference lies with the metallurgy,....

There is no comparison between street/OEM rotors and real racing ones. Although this is also reflected in the price differences, you do get what you pay for regarding durability/longevity and thats where the payback lies.


Marc,

I'd run those rotors a little bit more while keeping a sharp eye on those cracks.

Geoffrey

Gary,

What Steve said...I get about the same longevity out of slotted or drilled rotors from AP Racing. The slotted wear the pads at about a 2x rate though, so I prefer the drilled.

Potomac-Greg

If they're cheap(ish) then another reason to replace them is to avoid the risk of missing a session while you swap them out.

mhm993

Steve--who offers real racing rotors for stock black 993 brakes?

Count me on the use them but bring spares list.

Chaos

I run them until the cracks connect the holes or reach to the outer edge of the rotor. That said a lot of people here have more opinions than I do.

machina

Your kidding right?

I have seen the carnage from rotor failures twice and both situations involved total losses (but drivers survived). You may be willing to accept the risk but what about the rest of us racing next to you?

mark kibort

I understand your concern. Ive seen rotors that have come apart, but driving OEM and zimmermans for 10 years +, Ive always changed them at the point where the cracks meet the edge with no vibration (key) or other issues. These cracks, especially if they are only on the outside, which they likely are, are fine for a couple of more weekends, depending on how long they took to get like this. the OE and Zimmerman rotors do not fly apart like the japanese crap Ive seen on failed rotors at the track. they are pretty strong and have some meat to them. the rotors you saw fly apart, were they Zimmerman or OEM Porsche rotors? did they have cracks before they were used at the time of failure.
Its good to be concerned, but these cracks are pretty mild, and as was said, they should be monitored.

(as a note) If I was going to road america, Cal speedway or some other faster, and really brake demanding track, I probably would change them too.

Marc Shaw

Thanks for all the opinions (and for keeping the bickering and name-calling to a minimum).

I think I'll replace them as I don't have many track days left this season and I don't want to miss any time swapping rotors trackside.

Marc

RonCT

You know your wear rate... Do you have a 1-day event coming up or a 2. Hard braking track or light? For me at Lime Rock, Watkins Glen, or Monticello, those would easily be good for a 2-day at 4x25 sessions a day. Then they'd be ready for the recycler. I agree with you, I'd not change rotors at the track between sessions or days. I'd want to arrive and drive feeling confident I'm good for the duration whether it's a 1 day or 2 day event.

The good news is you don't have any cracks heading toward the outside or hub of the rotor, which to me means you've got some time (though I'm no expert, just going by what I've seen with my OEM rotors).