I have been reading this thread for a long time now and feel it's time to jump in. We have had our H3 for over a year now (13,000 miles) and almost from the beginning the rear brakes have made the groaning noise. Seems that the RR is the worst. Wife and kids have been disgusted that I "won't take it in and get it fixed". I have never had any luck with any GM dealer being able to fix anything other than a part that was physically broken in half or a car that wasn't running. The last thing I want is to have my expensive OEM rotors turned down as a temporary fix.
My mechanical engineering background tells me the brakes aren't going to fail, they just have a systemic design flaw. I keep hearing people tied to GM stating that rear brake "groan" is inherent in the H3. That may be correct. Another correct statement is that rear brake "groan" is NOT inherent in a quality designed and manufactured vehicle. How many cars have rear brake groan? None of the fifty or so cars that I have driven in my life.
I understand the fact that these brakes were taken off some other vehicle where they performed flawlessly. I work in a high tech field where engineers do that all the time. They take a component, assembly, or system and use it on another model of the product we design and manufacture. More often than not the component, assembly, or system does not perform as it did on the original model. Why? Because the operating parameters are not the same. The temperature of the product is not the same, the RPM's are different, vibrations, oscillations, natural frequencies all are different. This would appear to be the case with the H3.
Based on what I have observed, I believe there is a problem with the front to rear balance valve (or however they get the F/R balance). The H3 literature states that the braking system is designed so that the nose does not "dive" when the brakes are applied. In my opinion the nose still dives and I see no difference from other vehicles. It seems to me that when you brake lightly, there is no rear brake action and therefore no groan. When you do medium to hard braking, there is limited force applied to the discs and therefore they grab and release, grab and release, grab and release, which gives the groaning noise.
With all these complaints, GM engineers should get off their butts and figure out what the problem is. However, if they can't fix some plastic marker lights in a year and a half, I guess there's no hope for a brake groan problem.....
