There is a new TSB out yesterday for the clicking wheels. No longer replacing rotors with 2 piece, instead back to cleaning and using a different lugnut. here is the document.
#PIC5136K: Clicking Noise From Front Wheels - (Aug 28, 2012)
Clicking Noise From Front Wheels
Models: 2009 - 2012 Cadillac CTS-V
This PI was superseded to update recommended field. Please discard PIC5136J.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
A customer may comment on a clicking noise emanating from the front wheels. This condition is noticed at low speed (walking speed) during full wheel lock turns on dry clean pavement (Full lock parking lot maneuver). The clicking noise is generally noted as approximately 1 to 4 "clicks" per wheel revolution.
The CTS-V has lightweight high performance front rotors with an aluminum center. The clicking sound is caused by interaction between the wheel mounting face and wheel mounting surface on the brake rotor caused by the aluminum-to-aluminum interface.
Note: Do NOT replace the Front wheel or brake rotor for the clicking condition (The new brake rotors that were being installed previously for this condition should no longer be installed. The procedure to use now is cleaning and replacing the wheel nuts as described below.)
1. Remove wheel
2. Clean wheel as follows:
Use clean cloth dampened with GM Brake Parts Cleaner 12378556 or equivalent. b) Wipe the mounting surface of the wheel to remove any residual grey or black material that has accumulated on the wheel mounting surface. Be careful not to use the Brake Cleaner on the painted or clear coated surfaces of the wheel. It is also helpful to use a Scotch-Brite Cleaning Pad to aid in cleaning. Be sure NOT to use the scotch pads (Roloc disc) on the aluminum material. All cleaning MUST be done by hand, do NOT use ANY air or power tools!
3. Clean the rotor top hat as follows: a) Use clean cloth dampened with GM Brake Parts Cleaner 12378392 or equivalent. b) Clean the wheel mounting surface of the rotor (rotor top hat) to remove any residual grey or black material that has accumulated on the rotor. During the cleaning process be sure to clean the rotor near the wheel pilot at the center of the rotor. It is also helpful to use a Scotch-Brite Cleaning Pad to aid in cleaning. Be sure to NOT use scotch pads (Roloc discs) on the aluminum material. All cleaning MUST be done by hand, do NOT use ANY air or power tools!
Note: Be sure to thoroughly dry the wheel and rotor prior to installation on vehicle.
4. Reinstall wheels using replacement wheel nuts with P/N 9598179 (front wheels only, so need qty. 10 for this repair) (these can be identified with a blue color on the inboard conical portion of the nut (see pic) and torque them to 150 Nm (110 lb ft).
Note: If a car had the 2-piece rotors installed (Part number 20795300 & 20795302) prior to the release of these "blue cone" wheel nuts and has a repeat wheel click concern, perform this cleaning procedure, replace the wheel nuts with the new blue cone nuts, and torque to specs.