Coming soon: information on the R12 wheels.
The Front Brake:
Here is the correct front brake plate for the BMW R12. This is a very simple system that is one wire pull which pivots on two post.
The adjuster which leads into the brake plate should turn and click, this is what keeps it from coming loose. As you turn the adjuster out it pulls on the wire which it turn pulls up on the lever and moves the brake shoes closer to the wheel drum. This unit is complete and exactly how it should be assembled.