Hey i have a 2000 sunfire 4 door and i have a bad Klunksh noise in my rear brakes. when i hit the brakes it goes klunksh and it feels like they are sticking together,and then when i let go of the brake they release. this only really happens when i take out the car for the first time of the day and ussually only in reverse . i have ABS, but when this happens the ABS doesnt work and my tires just lock when i hit the brakes and the right rear suspension goes right down as if it was shot or just totaly broke but later i checked my suspension and they are just fine???

Sounds to me that your wheel cylinders are leaking brake fluid on your shoes. Have the same prob on my Sunbird.

I have the same problem... But i know for a fact my rear struts are blown so thats my guess on my problem... I'm just about to the point on giving up on these damn things.... Rear disc conversion

Did you ever figure out what the problem was or how to fix it? My girlfriend has a 2000 Sunfire 2.2 and it does the same thing and every once in a while the ABS light goes on. When she turns off the car are restarts it, it is gone. We especially have problems after it rains and driving the car for the first time.

Oh boy this was 5 years ago. I think the post above "wheel cylinders are leaking brake fluid on your shoes" was correct. everything you axplained i had the same issue. My suinfire was leased and we gave it back in that condition. man was that car in bad shape. Try to make a new thread with all the new guys around here you might find better answers then in this old one. gl

Check your drums? My 1999 has rear drums. I replaced the shoes. And what happened was that the drum actually was egg shaped, slightly. Put in a new drum, no more noise. A friend mechanic told me that it happens to my model. I told him sounds ridiculous. Tried everything else. Then changed the drum. Quiet again. Weird.

I have the same problem with my 94. I have noticed it more during the winter too when I had bald tires on the back when driving on the snow and ice, but also notice it everyonce in a while when it rains or drive it for the first time in the morning. Sometimes the ABS light comes on sometimes it doesnt. Most of the time it came on, it would stay on for a while even when I tried restarting the car. Drums, shoes, and shocks are good, leading me to believe its a problem with the ABS unit.