Leading & Trailing

Before I forget away I must write down about the important study on Leading & Trailing Construction Drum Brake. Though VW 1302 Super Beetle has no vacuum master to enhance foot brake pedal pushing power, I have been thinking that the reason was the back ground of inferior production technology or relatively lighter body weight, 870 kg. But the true reason of omitting vacuum master is the self-energizing effect caused by the leading side brake shoe. On the leading shoe the supporting position exists on the further portion of the inner circle of drum comparing with stopping power exerting frictional resistance by cylinder pushers. In another words the diameter of the supporting position in leading shoe is smaller than that of shoe surface and the difference of distance causes the outer vector when the shoe surface was activated mechanically. This outer vector is called as self-energizing effect.
There existed 1303 model with frontal disk brakes, so I hear, front and rear brake power balance must have been considered in combination with the brake master cylinder diameter balances, if changed the brake constructive design from drum brake system to disk brake one.