95 Taurus GL Rear Disk Brake Overheating Problem

Periodically over last 6 years I have had problems with rear disc brakes on 95 Taurus GL 4 dr. sedan with extra weight besides one driver. Replaced Emergency Brake cables, Front/Rear proportioning surge valve, both
rear calipers with rebuilts twice, burned out pads many times all with no real effect.
Replaced rusted rear brake lines and that seems to have cured it for one year then today after a 15 min. drive, I found my left rear caliper overheating again. Other Right rear brake is fine and never had problem with front brakes. The rear caliper overheating only seems to happen in warmer weather.
Any Idea what causes this plaguing rear caliper overheating problem that sometime melts or burns rubber seals?
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Have had same problem, dry/corroded slide pins.
Replace and lube.
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wrote:

Thanks guys,
I checked the slide pins. Top was free with lots of lube, but bottom was dry and almost stuck.
I also found both left and right Emergency brake cables seized solid again, even though these were replaced 2 years ago. (probably from New England salt corrosion)
Cleaned and Lubed both pins with silicone , switched places, one pin for the other. I left seized cables in place. Drove 130 miles last night with no sign of overheating.
Although this has been an intermittent problem affecting either right or left caliper, always triggered and spiked much worse by brake heating. So stuck pin may have done it.
Who sells a good pin kit (and EBrake cables) AND are slide pin holes (in forged steel caliper mount) known to wear out as well?
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On mdern cars, the front and rear brake circuits are divided into 2 systems as far as the mastercylinder design is concerned. This takes the form of : one cct supplies hydraulic pressure to both front calipers and one rear wheel, and, the other cct supplies pressure to both front wheels and the other rear wheel. Going by your symptoms and previous attempted fixes, its time to look at residual line pressure in the cct which supplies the problem rear wheel. One way to test the theory is too go for a drive for 10 mins or so, stop, jack the effected wheel up and test for resistance to turn. If its virtually locked-up, loosen the bleeder valve and allow a small amount of hyd-oil to escape. If the wheel is now much freeer,..yu've found the problem. Disc-brake design employs *some* residual pressure on purpose to hold the pad against the disks to stop accumulation of grit and dirt. Your trouble wheel must have too much res pressure. Perhaps a resealed MC or a new one will fix the problem,
Jason

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Not even close. It's either FF/RR or FR/FR diagonal

Disc brakes do not employ residual pressure, drum brakes do. matter of fact, some disc brake calipers are designed so that the piston seal pulls the piston back away from the rotor, these systems will have a quick take-up master cylinder. As for your logic that it's needed to stop accumulation of dirt, any dirt would fly off when the rotor is spinning...

Perhaps a collapsed brake hose.
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wrote:

That's right,..FR/FR with one rear wheel in each circuit.

Drums dont need residual pressure with return springs on the shoes. How many MCs have you pulled down? Haven't you seen the RP valves (replaceable) in the line ports?

The centrifugal effect will not stop a stone or chip of gravel from imbedding itself in a brake pad. Strange ideas,..where did you get them from?
Jason
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I had a rear caliper lock up on me on a Bosch ABS system used in late 1980's Chrysler products. I went nuts over the thing, thinking maybe I had problems with brakes hoses collapsing, or a parking brake issue, or rust in the lines. After playing with this problem for a few months ( This was my spare old car used for winter and mall parking lot duty) and sorting thru some misinformation given to me by a local shop I trusted I found a solution. The rubber caliper piston seal (not the outer rubber boot, but a rubber ring between the cylinder and piston) was causing the piston to hang up and not allow the pads to retract slightly anfter braking, causing overheatig as described. Again different car, but similar problem ?
Steve
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Those seals are extremely tight normally, hence the rounded end on the piston to aid insertion after o/haul, plus "brake grease" in the reco-kit. I had a '69 Valiant V8 with twin piston calipers which did sieze too. But that was due to a torn dust-boot admitting water, corroding the piston (coated steel) and then getting stuck on the seal-ring after they were G-clamped home to take new pads.
I didn't wish to can the previous poster,..and he may well be right on some points as one thing that continually changes is brake-technology and design. When the original poster mentioned frequent maintenance, it followed, I thought, the slide pins would be OK,..but?
Jason
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