mitch236

Never?!

Blacksport350

Never say never....I can crack ANY rotor!

KIYO_GT3

My front rotors are like this. They are longer than 7mm and they are growing.
Anyway, the mechanics at the Porsche dealer says "No problem."

db_gt3

Those rotors are garbage. Throw them in the garbage can. Then throw your mechanic in the garbage can.

Current Setup:
MPSC
Schatz Alignment
Cup Brake Ducts
Brembo Floating Rotors (front)
RS Flywheel/Clutch
Tequipment Roll Bar
GT3 Cloth Seats
Sabelt Harnesses
Center Console Delete

mitch236

Those rotors are fine. If I replaced my rotors every time they looked like that I would be changing them every couple of events. Unless a crack connects two holes or makes it to the edge, they should be fine.

jrgordonsenior

I disagree. Until they hit the edge they're fine....

A note on the aluminum hats and slotted rotors:
Initial outlay of $4,000. including the hats which are a one time purchase. I can buy a set of steel rotors from PMS for less than $600. The benefits to the slotted rotors are they last much longer, and they're 6 lbs.(+-) less per wheel of unsprung weight. Unfortunately, if you're racing they will thow you up into the next class at least in PCA. The collective Cup drivers here in POC voted this year to allow them without penalty and hopefully PCA will see the light. One other thing to note, when you hit a hard bump the aluminum hats will pull back from the rotors and your initial push on the pedal may scare the bleep out of you epecially if you're at speed. The cure is to lightly tap the pedal after a hard bump to firm up the pedal....

db_gt3

Why so expensive? My Brembo set was under $2000. Of course I got the "nice guy deal".

jrgordonsenior

Including the aluminum hats and labor? I'll take that deal, so who in LA's giving it away for $2k?....

AeroGT3RedWing

Unless you are purposely trying to crack them, no.

38D

That rotor is totally fine. If you throw it away, you are just pissing money away.


That is totally untrue. Slotted rotors do crack. The picture I posted earlier was a slotted rotor. Crack happen when you race.

AeroGT3RedWing

There aren't any slots ::

Properly designed/manufactured slotted rotors do not crack. 99% of drilled rotors crack.

38D

There are slots on that rotor, they are just out of view in the picture. I think there are 5 slots in total.


Once again, this is just untrue. The picture I posted is of a Coleman solid rotor with slots. It is a high quality part. Heat cracks rotors. In racing, you are pushing hard enough to generate huge amounts of heat, even with good cooling.

My post is based on my own first hand knowledge of my own brakes on the car I have owned & raced. What is your opinion based on (not a flame, just a question)?

AeroGT3RedWing

And the cracks are nowhere near the slots . . . hmm . . . unrelated to the slots perhaps?

In racing, conditions are totally different from the street cars this thread is about. Anyways, heat doesn't crack rotors, extreme temperature cycles do. You can let the rotor sit in an oven all day, but if you toss cold water on it, or bring it down from 1200 F to 400 F instantly due to excessive brake cooling, yes, any rotor will crack, blanks included.

An engineering degree and a strong background in thermo and aerodynamics. Again, you will crack anything going from 1200F to 400F, which is why there is such a thing as too much cooling. But slotted rotors do not create excessive street concentration that drilled ones do. I'd like to see a properly driven, properly cooled, and properly manufactured slotted rotors that has cracks in it related to the slots - i.e., not some random area that's nowhere near a slot.

AlanN

38D

Yes, I think my crack was unrelated to the slot. Cross drilled certainly do crack far more than solid/slotted. I would agree that it would be difficult to crack a slotted rotor on the street.