Brake proportioning valve. Options

[914Toy]

Like most of our cars, the brake proportioning valve is 45 to 50 years old. While it's design and action is relatively simple, - holds the hydraulic pressure at a factory determined maximum value (550lb/square inch?) while under pedal pressure, the probabilities of function failure must exist - whether through wear or contamination.

In my case, my brakes work well and when bleeding them all four calipers appear to experience free flowing brake fluid. My proportioning valve does not leak and there are no signs of abuse, or that it has ever been "serviced", but the latter is hard to tell. My guess is it still works or is "seized" and works as a simple T connection for the three brake lines.

I have refurbished stock rear brakes and have just installed Boxter front calipers on 911 Carrera suspension. Brakes are much improved and I can't get the rear brakes to slide under hard braking, suggesting the more effective front brakes "overpower" the rear brakes such that a proportioning valve is no longer necessary.

Any comments will be welcome.