By far the most common cause is sticking parking brake cables that are keeping the shoes partially-applied. The first thing to look at is both shoe frames must be touching the large anchor pin at the top of the backing plate. If they are not, you'll find the parking brake lever hooked to the rear shoe is pulled forward a little.
The next thing to look at is the parking brake strut bar between the middle of the two shoes. You should be able to push that forward about 1/8" against the anti-rattle spring pressure with your thumb. If the parking brake cable is stuck partially-applied, that bar will be tight. That will hold the front shoe out and it will try to grab the drum as it rotates.
Another cause of this is brake fluid contamination with a petroleum product like engine oil, transmission fluid, axle grease, power steering fluid, or penetrating oil. The clue is the rubber bladder seal under the reservoir cap will be blown up and mushy. The seals in the master cylinder will grow past the fluid return ports and block them. Park on a slight incline, shift to neutral, place a block about a foot downhill of a tire so you won't look funny chasing after the vehicle, then crawl underneath and open one of the rear bleeder screws. If brake fluid was trapped under pressure, that will release the rear brakes. Fluid contamination is a real serious problem with an expensive repair. Lets hope this isn't the cause of this problem.
If opening a bleeder screw does release the rear brakes, get them to drag again, then loosen the front steel line at the master cylinder. If the brakes do not release now, suspect the rear rubber flex hose is constricted. That is real common on some front hoses but not on the rear hose for this vehicle.
I forgot to ask, did this problem start after the brake work was done, or did you do the brake work to solve this problem?
Monday, September 21st, 2015 AT 9:20 PM
