Hopefully this subject hasn't beat to death but I didn't find what I was looking for in the search. To make a long story short my dealership won't replace my rotors because they have small cracks around the drilled holes. Apparently this means they have been abused and "heated." What do you guys think?

...safety issue! German metallurgical shortcomings are, sadly, well known. Time for a call to NHTSA."

And be sure to have them record EXACTLY what they're saying in writing...for future litigation, if needed.

if so, they should do it. if you're just trying to warranty your rotors after tracking the car, you're fvcked. cross drilled rotors, both OE and aftermarket, are known to get stress cracks when driven hard. if you look at any racing series, you won't find any cross drilled (or cast) rotors in use. you will however, find lots of slotted rotors, because they don't get stress cracks *due* to the slotting, but any rotor is subject to some cracking under extreem thermal deress.

<img src="http://pictureposter.audiworld.com/17157/crackedbrembo.jpg">

cross drilled is pure bling, and audi knows it. so does mercedes, bmw, and porsche. looks sell.

It's not even up for debate.

if you're thinking of unsprung weight, remember that rotor mass is what helps to absorb and dissipate the heat generated in breaking. by cross drilling the rotor you do three things 1) reduce mass, and the thermal capacity of the rotor 2) introduce micro fractures in the metal, which grow into cracks under hard use 3) introduce a path for brake dust to travel into the veins of the rotor, providing the veins with insulation, and therefore reducing the rotors ability to cool / dissipate heat via its internal vein structure. oh, and 4) reduce the overall surface area of the rotor, which reduces modulation ablity and increases the required pressure on the pad / rotor to slow the car.

I can't think of a single racing series that uses cross drilled rotors. Can you?

slotted rotors are superior. the slots cutting edge "sweeps" the pad face clear and provides excellent bite, while reducing the chances of stress cracks and while retaining as much rotor mass and surface area as possible.

reduction in unsprung weight in braking systems is made up in lightweight hats and calipers. (ie: a fixed caliper of equal strength to its slider counterpart weighs less).

not to be a dick, but can you think of anything else i've missed?

C'mon now. In almost every road test they did on this car it was driven like gangbusters.. some on racetracks.. Sounds like another case of uninformed dealer or just plain greed.

i'm not trying to be a jerk about it. it just so happens that x-drilled is inferior to slotted for ultra high performance applications. on the other hand, it looks great, does marginally improve handling, and x-drilled rotors make a more uniform sound when braking at slow speeds, which does matter for OE applications.

i was being sarcastic.

sorry if my subtle, dry, humor is lost in the internet. :p

Cast/drilled slotted rotors (street driven) usually crack from instant hot to cold situations.
If you get the rotors hot going down a long hill and run through water of any substance, the rotors will crack.
If your brake pedal isn't pulsing from a large crack I wouldn't worry about them at all.

<b>CAST</b> drilled rotors do make a difference in pad life and fade resistance.

You are correct that slotted rotors are better in extreme apps.

Thing is I know this car has never been to the track. Well, actually I'm the second owner but I highly doubt the last tracked it. One minute they are telling me the brakes look fine with normal wear, the next they are telling me the stress cracks are a sign of abuse.

No track days and I'm just trying to silence the obnoxious brake squeal. Sounds petty but these bastards scream like a banshee when I come to a stop. If they need to replace the rotors then so be it, but I'm not about to take no for an answer. Your brakes look exactly like mine by the way. Small stress cracks surrounding the holes. I'm assuming this is typical of drilled rotors.

rotors with the holes CAST in, not drilled (basically porsche OE)

I will ask anything you guys want me too...

I'm not aware of any manufacturer selling a car with rotors actually drilled.

but there could be more. i'm not an expert on how each manufacture makes their cross-drilled rotors.