Mechanics

REAR BRAKE CALIPERS WILL NOT FULLY RELEASE

2002 Chevrolet Suburban • 91,000 miles

After driving vehicle for a short time, both rear calipers will not fully release and have a drag on rotors. It will get worse as you drive until the rear brakes, rotors and rim are very hot and brakes are giving off a burning smell. I have duplicated issue and jacked up and find both rear tires hard to turn by hand, removed tires and removed caliper slide bolts and had to remove caliper from rotor by prying off with screw driver. After vehicle sits for 15-20 minutes, the pressure will relax.
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Mcjr
June 5, 2012.



Caliper slide pins have been removed and greased, there appears to be no crimped brake hoses. I am being told it could be the calipers, brake hoses, master cylinder, etc. How is the best way to trouble shoot this so I am not throwing parts at it?

Tiny
Mcjr
Jun 5, 2012.
It is probably the pins. They are made for the caliper to move back and forth on and can get gummed up or bent. More than likely they just need cleaning and greasing.
Get some brake cleaner and some paper towel type shop towels and some high temp axle grease.
Clean the pins and the holes they travel in completely. Inspect for large bends then put a little grease on the o rings if applicable. See if the caliper will slide freely on the pins. If so, grease them up a little more, make sure they bottom out because too much grease will keep them from going all the way in.
Make sure dirt boots are in place and don't have tears. Check for movement againa and then install.
Test drive and check for operation.

Have already cleaned and greased the pins and holes they travel in. There is pressure on the rotors from the calipers unitil vehicle sits for a short period of thime and then they free up again until you drive for a short period of time. Is there anything else it could be?

Tiny
Mcjr
Jun 5, 2012.
It is either a clog in the line or the master cylinder has something clogging the rear port. That is probably the case. If it were the piston failing to rerun the front brakes would stick as well. I would check parking brakes return springs just for the sake of being safe.
Also the proprtioning valve could be clogged in between the front/rear split up to the rear left/right split.
I would try replacing the master cylinder first as it is an easy job and not too expensive.
If you could make test fittings for a vacuum pump, you could find the clog that way, but it is costly and tedious.
Witht the mileage, if you have never flushed the fluid, I would try a master cylinder.