A while back I had an annoying clicking noise coming from the front wheels, it was only after spirited driving so you could assume it was caused by heat. Diagnosed by 2 reputable works shops as faulty wheel bearings, you can spend anywhere from $500 - $1000. Second hand, low km parts or all new hubs and bearings are the options. After this mandatory spend I was not impressed that the noise was still there. Closer inspection proved it was being caused by my new 2 piece rotors.
Several others on this forum experienced the same fault and this was taken up by the Manufacturer with many emails and calls. One set was sent back for investigation. To the best of my knowledge the fault has never been addressed leaving me wondering how many other people around Aus. and the world have been pissed off by this issue. Remember it costs $1000 first for hubs and bearings before most people realise its the rotors. One guy over east replaced 2 sets of bearings and hubs and both CV's before he found it was the rotors !!!!!!!
I found the Rotors being anodised move against the hub or rim when hot. Called "metal pickup" by Engineers it’s due to the difficulties of clamping dissimilar metals whilst applying heat. This click click noise was very loud and what I would call "not acceptable behaviour" (said with Super Nanny accent) from any rotor. I used a torque wrench to manufacturers specs during testing.
I then removed the anodising from parts of the rotor Top Hat that contacted the rim and hub. Aesthetically this is not an issue and things look as bling as before, it's just not something I enjoy doing to $800+ rotors. I used a coarse then a fine wet and dry sand paper with a sanding block and 5 hours of elbow grease. The sanding block is necessary to keep things square, take your time as it would be very easy to unbalance the rotors. Not sure if it’s the hub or rotor side that caused it but who cares, it’s gone now. I have since added some Coppra Coat high temp grease to the same mating surfaces to reduce the wear rate. A year later and they are still behaving themselves.
Disclaimer: Its your problem if you stuff it don't blame me.
Photo's taken after a month of use before using Coppra Coat Grease, note the wear marks.
