360 rotor cracking--when to change rotor?

When you start seeing cracks, change them. IMO, the best solution would be to go with slotted rotors, or maybe just plain face.
Is the stock cooling stuff in place?

 

ummm, immediately... never skimp, go cheap, or procrastinate when replacing safety items. buy slotted rotors next time eliminate cracking issues.. (drilled rotors are only "show" on street cars.. if you are using your car for track or track like situations, make the switch to slotted rotors..) good luck

 

I run Challenge cars... my rotors show cracks after two laps. Dont worry about them until the reach across the holes.

 

That is total bull on the slotted vs holes being for show. I cannot believe someone would post something like that. I have tried both and my friends slotted will also show cracks if you run hard.

 

If the micro-cracks reach an edge or multiple cracks start to intersect, then I would change the rotor. I moved away from drilled rotors some time ago, so I can't advise there.



Lou

 

Crossdrilled rotors are known to crack, as they reduce thermal capacity and create stress risers. They do make rotors lighter, and look "cool" on the street.
Slots provide extra bite, and don't provide a place for cracks to develop.

BTW, where's your profile?

 

If you replace your rotors with new ones, that are also cross drilled, get the new ones cryogenically treated before installation. This will help prevent the cracks.

 

BINGO +1 When multiple cracks intersect and reach a combined length of about 3/4" it's time. And as posted here by nunov, plain/slotted track rotors crack the same as drilled just not as soon.