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]

@barefoot

I think Mark was referring to cracking the hard line connection, not opening a bleeder valve. There's really no way to crack a hard line under pressure without making a mess everywhere.

@ stugray

I used the Tilton 90-2003. You can see it here

Tilton Prop Valve

and you can see the document showing the performance curves in a previous post in this thread.

"Did it fit easily with no mods or is this a radical pedal modification?"

Somewhere in between. I guess it depends on your level of skill. When I was learning the trade, mechanics often made their own parts, but these days it seems most aren't inclined to do a job unless it's an easy bolt-on deal. This is definitely not a bolt-on deal.

I had to make several hard lines. By the way I used Eastwood's great line of brake tools to do the job. They make a brake flaring tool that makes this task much easier, and is better than any other tool I've seen for this job. You can see it here.

Eastwood Flare Tool

I also had to make a bracket to hold the valve and T-fittings. I did this fast and nasty, since I was just trying to prove to myself the idea would work. It took me about an hour and it looks very ugly.

I suppose I should have taken some pics, but as I said, I was in a rush to get it in and see if it works. Now that I know it works I will take some time to make a nice bracket, and I'll post pics as I do that.