'93 Disc Brakes

[heyhar]

Hello- We have a '93 Sable- ABS with rear discs. I removed the left rear wheel (rotating tires) and found the pads worn into the disc. The calipers and pads were barely a year/10K old. Removing the caliper, I couldn't push the piston back into the bore. So, I got new (rebuilt) calipers, pads, and rotors. Bled 'em out, and they feel great. But, they're heating up (dragging?) again. The parking brake cables seem to disengage fine. Does the little proportioning (?) valve on the left rear control arm have anything to do with this? I had to engage it to bleed the brakes. Or, am I looking at an ABS problem? Master cylinder replaced two years ago, front brakes work fine, ABS seems to operate properly. I'm stumped...Thanks, Ray

[KimMG]

1.) A special tool is required to turn and press in the pistons on rear calipers.

2.) Flex lines deteriorate on the inside causing blockages that act like one-way valves. These blockages will prevent the caliper from releasing.

[KimMG]

I received this private message from heyhar.

"Took your advice and replaced the rear flex lines. All I have to say is...WOW. I've been working on (playing with) cars for 35 years, and never ran into this particular problem. Thank you!!!...Ray."

Ray, I'm glad your problem was an easy fix. I have posted your private message to me for public view because I believe solutions should be shared.

I have found bad flex lines to be a common problem (especially on cars that are ten years old or older), but usually overlooked because the hoses rarely show any external signs of trouble. Old brake flex lines will become mushy and expand, absorbing some of the braking energy. Just remember the same material that is used in wheel cylinders, seals in master cylinders, and in calipers is used in making the rubber hoses in brake lines. The seals in these items deteriorate and show visual signs of breakdown.
Last June someone had posted the same problem as you on their '95 Sable. His mechanic kept replacing the rear caliper under waranty but didn't fix the problem until the car's owner mentioned the flex line. When the car's owner cut open the old flex line, the internal deterioration was very obvious. Because there was no external signs of trouble with the flex brake lines, the mechanic lost a lot of labor dollars due to the fact that he assumed it was the replacement calipers causing the trouble.