Off Brand but---

[Willie White]

I ask your forgiveness for an off brand question. My 83 VW diesel Pickup. I just replaced the brake pads. Now I have only one side that brakes effectively. By one side I mean that the left front and right rear will readily lock up on my stone driveway. Not so the other side. Jacking up the offending side proves that the brakes to those wheels will prevent hand turning of the wheels. The pedal seems to be a bit soft and sometimes will go slowly down more than it should. I have bled that side and no air comes out.
Question: Is there a proportioning valve on this unit?? Could this cause these symptoms?? If so can it be adjusted. Is the Master cylinder at fault??
I hesitate to consider the vacuum booster at fault. What other components are left??
I would surely appreciate your input and again apologize for the off brand thread.