Is there a third party replacement brake-proportioning valve (or rebuild kit for a stock one) available for a stock 914 2.0?

Mine is in place, but I'm not sure what condition it is in. The car has sat for many years - not running - so I think I'd rather err on the side of replace / rebuild than trust that it still functions as it should.

Brake system has been "open" for about a month now. Was closed until I rebuilt suspension (front / rear).

Sources / partnumbers would be helpful.

Thanks,

Len

PS: And, oh as a side, this really confuses me. When I took the front left caliper and disconnected the brake line, the master cylinder started to leak like heck. Fluid just started coming out - seemed to come out the front. Anyway, it wasn't leaking until I disconnected the brake line from the caliper (best I could tell).

Have you contact Eric at PMB Performance. He is a vendor on our forum.

Yes I have.... bought 5-lug front end parts from him, rebuild kit for 911 calipers.. but I don't see on his site that they have either a replacement or rebuild kit for the valve....

Talk to Chris at Tangerine Racing. He did a major study of the proportioning valve.

I don't think they tend to go bad because they are basically a spring driven plunger.

Do not remove it because they prevent rear wheel lock up.

John

with John.

Len,

This is a pressure regulator not a proportioning valve.

There are no rebuild kits available and they rarely go bad (if ever).

I would flush the valve with denatured alcohol and re install it.

This valve prevents your rear wheels from locking in the event of a panic stop. I would call it a "must have" item on any street driven Porsche.

Unlikely there is a problem with your unit.
Clean and put back into service.

Also, contrary to popular mythology, there is no need to bleed them after the system has been opened up.
There is no fluid volume inside and any air bubbles pass through to the rear calipers quite readily.
The large chamber is dry & only contains the spring ass'y which provides the pressure limiting function.

It is nice when knowledge can replace (incorrect) mythology.

That was great work to dissect and test the valve and post the results, Chris.

John

Worked on one of these years ago. Put some pictures here
http://forums.pelicanparts.com/porsche-914...-revisited.html

I'm still not comfortable that the valve performs exactly as the factory intended.
My pressure tests were inconsistent with the factory description and graph provided in the service manual.
However, it definitely does limit pressure and prevents rear brake lockup.

I do believe the setting was either too low from the factory or the spring has lost some tension over time and someone experienced and prepared to do threshold brake testing could up the spring pressure a good deal without endangering themselves.
I shimmed mine 1/4" and am nowhere near getting rear lockup during max braking.