rear brakes locking up

[96_GP.SE]

Alright guys, I have a problem. Everytime I hit the brakes, my rear brakes completely lock up. But if I let off, they unlock. Friday night, I was going about 45 and went to slow down for a sharp curve in the road. My brakes locked up, back end of my car slid around and made me lose control. Hit two ditches. A culvert. Ripped out two mailboxes cemented into the ground 5 feet. And ripped a gas meter completely out the ground. I've replaced the lines. Pads. Calipers. Rotors. I don't know what could cause the problem. What do you guys think? Need to get this fixed asap as this is my only vehicle. Sadly sold my truck 3 days ago...

[Crazy K]

sounds like they are bound up already. You may need new rear calipers. You might be able to run them through a range of movement by rotating them in and applying the brake a few times and repeating, this should confirm that them are not totally shot, and unbind them if they are stuck.

 

 

I found this to be true: if the lower sliders are stiff or bound, I disassemble them and enlarge the bore they sit in just a bit (a did a rough job with a round file), this has solved the binding in that car...

[White93z34]

I kind of wonder if there is a problem with the internal valving in the master cyl.

[rich17]

What kind of car?

[white4d96]

Judging by his username, I'd say a '96 GPSE.

 

I had a failed master cylinder that caused my rear brakes to lock up. I think the replacement was $30 after the core fee from Autozone.

[GtpKo]

What about brake fluid leaking on to the braking surface? May be a shot in the dark, but that happened to my '90 Sunbird. I had brake fluid leaking on one of the rear brakes and every time I braked moderately, it would lock up and nearly throw me out of control.

[96_GP.SE]

I've changed the rear calipers. The rotors. And the pads. And it still does it. But the weird thing is. Some days it does it. Other days they are perfectly fine. I will change the master cylinder and try your suggestion Crazy K. I'll keep y'all updated with my results. Thanks for the suggestions.

[rich17]

Unplug the ABS fuse and see if it does it as well.

[Schurkey]

Rear tires properly inflated? Still have tread? Wheel bearings in good condition? Park brake works appropriately?

[redgrandprix]

i had an issue similar to this where one of my rear wheels would become extremely hot to the touch because the brake was locked up, i replaced both rear calipers but in the end i had to buy a $14 hose the goes from the brakeline to the caliper, apparently these hoses are double walled and sometimes the inner wall will collapse in on itself which then doesn't allow brake fluid to leave the caliper effectively holding the caliper tight.

[rich17]

Another very good point

[96_GP.SE]

hey guys. so i got my rear brakes fixed. the master cylinder was bad. all 4 brakes locked up on me and they wouldnt unlock. my master cylinder was also leaking fluid. thanks for the help in finding my problem.