quote:Unlike almost every other car that uses such a valve, in Panteras there are no return springs inside, so manually returning the shuttle to center is the only option
A return spring would defeat the full purpose of that warning system.
When the brakes are applied and one brake circuit won't hold pressure, the shuttle valve moves to the low pressure side and completes the electrical circuit for the dash warning light.
If the shuttle valve had a return spring, then, when the brake pressure return to zero (foot off of the brake pedal), the shuttle valve returns to a centered position and the dash warning light would cease to be illuminated, giving the driver a false sense that the braking system is OK.
As I recall, that shuttle valve assemble is from a Ford Torino.
John