OK, so I have ordered (and now received) the Audi ceramic kit. On reviewing the kit and its parts, I noticed there were fine cracks all over the rotors' surfaces. They largely seemed to emanate outwards from the cross-drilling and then run all over the discs. How much of a problem is this? As from my reading it would seem to compromise and shorten the expected lifespan of the rotors as these would only expand with heat cycling.

I have asked around with a handful of people I know involved with autos and racing but would like to get some more info from anyone who might have installed or is familiar with ceramic brake systems. Does anyone have knowledgeable advice or information to offer?

Please no speculations - I would rather keep this to people in the know about these silicon-carbide brake systems and rotors.

Many thanks in advance.

Oh and here are the pics; they are about 3MB each and large to show detail.
<a href="http://www.adrive.com/public/e016501c3a61d534445c5f204cfa318efeb2c3bbd80fd33b5e 1b21fb9e55a8b2.html" target="_top">whole rotor</a>
<a href="http://www.adrive.com/public/afec227922b8fc8b54fb3e30d5a08582fcc0fdc67ca38582c7 e4f4fe4042bc3d.html">pic 2</a>
<a href="http://www.adrive.com/public/0239951cb079b6912930b5bf32734b7efbc90957cb820bfb96 e8a4185b835c00.html" target="_top">pic 3</a>
<a href="http://www.adrive.com/public/ec2b6c201be1c2c5b3e5c571edd9051bf6db5ad724f8e4f93a de66b311214e9a.html" target="_top">pic 4</a>
<a href="http://www.adrive.com/public/9cb26e09da79618f3eb92be73147b89fcd7ea0548eded71540 950db0921f8960.html" target="_top">pic 5</a>
<a href="http://www.adrive.com/public/32fc0f849a50e411a771752692c2a2edb63ee46251df62f1ec 3d488aba18a1ac.html" target="_top">pic 6</a>
<a href="http://www.adrive.com/public/2e4ad265f3db651168657177395e5df98a6c85bb8138f03fbc 1b4c3d56ad8bb1.html" target="_top">pic 7</a>
<a href="http://www.adrive.com/public/f472d5d0d4ca6f6dafe618a5de81cdbf78dcf23e5fea119be4 90217a94de46fe.html" target="_top">pic 8</a>
<a href="http://www.adrive.com/public/ad7ce5a1af52627f9d9530537cbe79c12ee67269ba659ad6ee a444f176d01e5a.html" target="_top">pic 9</a>

The cracks are beneficial only in SiC &amp; c/c as they prevent the heat from propagating...interrupt the thermal path. They are a result of residual out-gassing (leaving voids in place) of the brake disc from the heat generated during heavy brake applications and typically not related to stress cracks.

For steel discs cracks are not what you want on and are cause for alarm because of resultant stresses.

I worked in the carbon brake industry for 30+ years before retiring. The company currently manufactures the V-22 Osprey brake discs which are c/c enhanced with Si which gives the brake discs a high coefficient of static friction to compensate for the very poor static coefficent of carbon. :)

Well, thank you for the input. I did some more digging and asking around and it turns out these cracks are to be expected. During the ceramic process as the fibres merger, etc...once cooling occurs these fine cracks appear - they are tension relaxation cracks which do not affect the performance or safety of the systems.

Can't wait to stomp on the brake pedal this weekend at VIR!!!

And what size wheel does it require?