Okay...My 1987 is acting up again. Well...these have been known issues with my friend (previous owner and only 20), and I'm slowly finding them out. He isn't mechanically competant, to dianose, or give a good discription of possible problems. So I'm slowly sorting this car out. I prefer to do all the work myself to save money on labor if possible. Anyway, to the point.

I had heard a noise in the rearend backing down the driveway. It's a fairly steep grade and it requires copious braking to make it down safely in reverse. Well, as this is happening, the car will ocassionally make a groaning noise...sounds like ABS kicking on...and the pedal will suddenly fall to the floor, but the brakes are still responsive, and then just as it fell, it will return and the noise stops. I figured it might need a rear brake pad job. I proceeded today, to do both front and rear, to see if it would cure this awful noise.

For a while it did. But, I did notice that when I was changing the right rear pads, that the 17mm slider bolt and 15mm cinch bolt for the caliper were not properly tightened. I assumed this might have caused the noise. Also, the pad tension springs were poking through the caliper inspection hole. I assume someone had done these prior without any knowledge of corvette brakes. All but one caliper was like this. I remedied these issues and went for a check drive. All things pointed to the problem being fixed and the pedal feels firm and never dropped. I had also topped off the brake resevoir for safe measure.

Later today, I decided to cruise for a while, confident that I conquered one more ailment. While backing down, she moaned and groaned briefly. But, this time the pedal felt solid and never went to the floor as previously stated. Now I'm even more confused and I can't seem to pinpoint it to a certain side. Before I knew the right side was making it...now it seems the whole back end is filled with that sound. I will say that it doesn't occur frequently and is only when the car is first started after a long cool down. It has also done this going down forward. But, its rare for it to do it when the car is facing forward down the driveway.

 

are the brakes moaning? (scrubbing)
does the rearend have proper oil ?
does it have a different or rebuilt rear end?

 

I'm pretty sure its not the pads themselves rubbing on the rotors. I just changed all sides and made sure everything was relubed, snug, and that they were set-in properly. It doesn't seem to make sense that it would be the differential...only because it does the noise when brakes are appliedm and usually only once when the car is first started...like for the first time in a day or after a long cool down. I looked at the Diff and it doesn't show signs of leakage. The car has 65,000 miles on it. Does this year corvette have ABS on it? I didn't think so. I tried a Panic stop and didn't get any pedal pulse...unless that's what's causing the issue. I don't know.