Rear brake pressure regulator valve, Brake repair Options

[DamonsCarrera]

The brake pedal on my 914-6 is very spongy, even after repeated bleeding with a pressure bleeder. I isolated the problem to the brake-proportioning valve or pressure regulator. I cannot seem to get the brakes properly bled with this valve in the system.

I've read other posts by some here and it seems this valve is a source of some debate . Is there some trick to bleeding the brakes with it? Do I need to bleed the brakes the old-fashioned way, have someone push on the brake pedal?

[Eric_Shea]

I think there are other aftermarket valves available, for instance at this link here.

There's 100's of bias proportioning valves available. No pressure regulators that I know of and they're quite different as the 914 is the set pressure variety discussed in the Bosh paper. That's what I meant when I said <<The aftermarket ones are bias controls, reducing fluid flow to your rear calipers.>>

when I take the valve out of the system I can bleed the brakes just fine.

So you've bled the system both ways? You put a T in and tried it without the pressure regulator?

Sounds like you still have some air in the pressure regulator.

Bed the pads and then re-bleed the rears after driving the car (bumps, rail-road tracks, etc.) All of these things help dislodge air bubbles that may be trapped in the system.