I can't find one on ebay, rockauto, autozone, carquest, napa, or pepboys.

What do i do now, is there anyway to rebuild it? my front brakes occasionally seize up.

this is driving me crazy because i just dropped 250$ on a complete brake system overhaul. New master, booster, pads, shoes, calipers, and drums.

Also, it's not the flex hoses i replaced those first, and when i hit the proportioning valve on the firewall they magically work again...

What year car are we talking about? There are considerable differences in the brakes over the years.

1976 280z

i keep forgetting to put this in the first post

edit: this is for the one on the firewall

Edited July 5, 201113 yr by robftw

1976 280z

i keep forgetting to put this in the first post

You may want to just add it to your signature, then it's always there.

Take yours apart and clean it. You'll be amazed at the crap in it. If that doesn't do it I have a couple of spares.

Yes a refurbish is recommended.

You can put a brass wire wheel on a drill and clean up the outside nicely too.

I had the same challenge trying to find one that could be rebuilt. I bought three used ones before finding one that was not so corroded and pitted that it could actually be fixed. If the used one you find has been sitting a while there is a good chance it will really be gummed up inside. Are you absolutely sure that's the problem? What are your symptoms? When mine failed the brake light warning would come on and the car felt like it had only about 60-70% of the normal braking force. The car would stop, but in a much longer distance than it should have. I ended up taking it completely apart, cleaning everything and reassembling. I was lucky as that solved the problem.

Keep in mind, every hard line flex hose, pad, caliper, rotor, and drum were replaced.

But my symptoms are:

car leans to the right when braking softly

hard to depress pedal

When i jack the car up off the ground both tires are hard to move

occasionally when its real bad and i need to stop, rotors get red hot from friction

brake light occasionally comes on when braking

Feels like braking force diminishes 50-60% on occasion

im going to take apart the valve this weekend and have a look

How do you get in there to remove the proportioning valve with the engine in? I bent and installed new lines with the engine out and had to install the master lines to the valve after the engine was installed and remember that being about as miserable a job as I had in the entire time working on my Z.

It's easy to get at for me.. The proportioning valve is the one on the firewall right above / next to the transmission tunnel unscrew one bolt and its out.

I plan to clean mine out sometime tomorrow

No matter how many times you flush,crap stays in the P-valve,tee's and other fittings.A manual cleaning is the only way.

I'll be interested in what you find when you do the disassembly. I'm going to guess it may be something else. Your symptoms would indicate to me that you have multiple issues. You didn't say if you replaced the booster or master cylinder. The hard to depress pedal does not sound like a proportioning valve. When you say both tires are hard to move with the car jacked up are you talking front or rear? Pulling one direction or another also does not sound like the proportioning valve as I believe the proportioning valve only modulates front and rear pressure not side to side.