I own a MK6 Transit Tipper and I have had a lot of problems with the rear drum brakes...They are pretty much permanently locked on, and they have been like this since I bought it. Basically I adjust the rear shoes, and when I press the pedal the wheel cylinder pushes the shoes out but they don't retract. They get stuck against the drums and rub when I'm driving.
It has had brand new wheel cylinders, shoes, fitting kits (all the springs, ect), self adjusters, and all hand brake cables. It has also had the brake power regulator adjusted + had the brakes bled multiple times by me and a garage. But after doing all this, the rear brakes are still the same. Why? It is doing it to both rear brakes, but one is worse than the other. One gets red hot after I have been driving, even if I only drive for a short amount of time. I had the brakes tested on a brake roller and they are absolutely terrible. I even spoke to the mechanic after and he had no idea what the problem was! Do any of you guys know?