9in drum brakes

72,
For some reason most of my post [ #12 ] did not get printed. So I will try again.
For the same line pressure, a drum brake Chrys car will stop quicker than a disk brake car.
That is because C [ & many other brands ] use duo-servo [ DS ]drum brakes. This action links the two brake shoes & causes a wedging action of the shoe against the drum. In effect, the braking force gets multiplied with DS brakes & provides deadly stopping action. A highly efficient system.
In contrast, a disc brake is nothing more than a G clamp & has no multiplying effect. It also loses some clamping force because of it's open end which spreads open.

A disk brake requires faaaaaaaaaaar more line pressure than a DS drum brake to be effective. That is why proportioning valves are used with disc/drum brakes, to reduce pressure to the rear drums which would otherwise lock up from the high pressure the disks get.