[Greg Reimer 7376]

In review, it's possible that the positions of the master cylinder reservoirs could be reversed. Drum brakes are self-energizing,meaning that as they apply, the front shoe is pulled into the rotating drum,thereby activating itself and pushing through the brake adjuster star wheel on the bottom, the lower end of the rear shoe. They require a volume of fluid to work, where disc pads are applied through pressure.Disc brakes require only a small amount of fluid under high pressure to work. Make sure they can release rapidly even if it means removing any pressure retention valve or device in the m/c where the line goes on.Drums and discs would not be compatible on a single master cylinder, like a 66 Chevy or something like that. Before adequate enough stopping power for the front brakes could be achieved,the rear tires would be up in smoke.The only exception to that rule I ever saw was a 65 Triumph Spitfire that a friend of mine has. The rear w/c's are probably 1/2" in diameter, and the front caliper bores were fairly large.On a British car like that, you don't buy rebuilt calipers or wheel cylinders-they sell you a seal kit. I went through the whole system on that car, and it worked fairly well. It was different, but I don't care to be an authority on how they build cars over there.Hopefully,your project will be easier to sort out.The large reservoir on a tandem master cylinder is for the disc brakes, the small one is for the side with the drums.