I tried to upload the PDF but this forum has a ridiculously small limit for them. Google: L-SB-0044-10.pdf which describes the issue if you want to know more about it.
I just had my car in for this and they replaced both the pads and shims. After bedding them, the squeak has returned. It happens from about 10mph-0 on light deceleration - basically when crawling in traffic, which happens 50% of the time I'm in the car. It's really annoying and is going back to the dealer later this week for additional troubleshooting.
My RS 4 did this with Brembos as well, but a few stomps on the pedal at freeway speeds solved the issue. So far, no go with the IS F.
L-SB-0044-10
July 2, 2010
Rear Brake Squeak
Service Category
Brake
Brake (rear)
Market
USA
Applicability
Introduction
Some 2008 - 2010 model year IS-F vehicles may exhibit a squeal or squeak noise from the rear of the vehicle when lightly applying the brakes. A new rear brake pad kit has been made available to address this condition.
Section
Warranty Information
APPLICABLE WARRANTY
^ This repair is covered under the Lexus Comprehensive Warranty. This warranty is in effect for 48 months or 50,000 miles, whichever occurs first, from the vehicle's in-service date.
^ Warranty application is limited to occurrence of the specified condition described in this bulletin.
Repair Procedure
1. Conduct a road test to verify the noise condition. Noise usually occurs during stops with light pressure applied to the brake pedal.
2. Remove and replace the rear brake pads and anti-squeal shims with the updated parts.
For complete removal procedures refer to the Technical Information System (TIS) applicable model year IS-F Repair Manual:
^ 2008 / 2009 / 2010 IS-F:
Brake - Brake (rear) - "Brake (Rear): Rear Brake: Removal"
For complete installation procedures refer to TIS applicable model year IS-F Repair Manual:
^ 2008 / 2009 / 2010 IS-F:
Brake - Brake (rear) - "Brake (Rear): Rear Brake: Installation"
NOTE
^ When replacing rear disc brake pads, the anti-squeal shims MUST be replaced together with the pads.
^ When applying grease per the Repair Manual, use the grease enclosed with the rear disc brake pad kit or supplied grease: Part # 90998-94072.
3. Road test the vehicle to confirm the rear brake noise condition is NO longer present.
Digger08