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?

[DamonsCarrera]

Sorry for the late response. Work has been a bear lately.

I bled the brakes with the whole rear of the car (regulator and rear calipers) out of the brake system by replacing the line from the master cylinder to the inlet of the pressure regulator with a bleeder valve at the 90 degree connector where it comes out of the back of the firewall. When I do this I get a perfect solid pedal.

I also bled the system with only the rear brakes disconnected by replacing the hard line to the rear caliper on each suspension control arm with a bleeder valve. In this case I get a spongy pedal. On initial application of the pedal it feels soft, and if I keep applying pressure to the pedal it goes all the way to the floor, over the course of about 15 seconds.

I've tried various approaches to try and get the air out, tapping on the regulator, using speed bleeders and aggressively pushing the brake pedal, going around the car 4 or 5 times. Nothing seems to work.

So I guess I have to take out the regulator. I don't have a lift at home. It doesn't look terribly easy to get access to it. I guess I have to take out the heater controls and oil lines.

Has anyone else had this experience?