Brake Bleeding Anomaly on my 66

[Grounded63]

You dont add a vacuum brake booster just to get more line pressure. You get less required driver effort, for the same or better braking performance.

Disk brake calipers generally require more fluid displacement to operate effectively. ( and also more line pressure ) Than drum wheel cylinders do. Which is why you move up the a lager bore master cylinder.

Changing to a " worse " pedal ratio doesn't result in less line pressure. Your leg having " less leverage " doesn't really matter. When you've added power assisted brakes. That lets you achieve the same or greater line pressures. With less physical effort.

Race cars also have . . . Racing calipers, racing compound brake pads, racing disks, race compound tires, racing suspensions. It's not just a manual master cylinder that makes them stop just fine.