Here's why:
* Dual Master Cylinders: The 1974 Beetle used a dual master cylinder, one for the front brakes and one for the rear. This means there are two separate reservoirs.
* Warning Light Switch: The extra port on the master cylinder is typically connected to a switch that activates the brake warning light on the dashboard.
* How It Works: The switch is designed to sense pressure in the brake system. When brake fluid pressure drops below a certain threshold, the switch closes the circuit and illuminates the warning light, indicating a potential brake problem.
Note: Some older VW Beetles might have had a slightly different setup, so it's important to confirm this by checking your specific model and year in a repair manual or online resources.
