Proportioning valve?

[TealFestiva]

'93 Festiva...brake pedal sometimes would depress all the way to floor before brakes engaged...scary at first, but got used to the adrenaline rush...got my backyard mechanic to check stuff out, and after couple of times, settled on brake master cylinder. Replaced that with Advance Auto stock part. But fluid disappearing from reservoir. Eventually found Proportioning Valve leaking. Where do I find that part? Can we swap out with valve from another make or Aspire? Advice greatly appreciated. We are original owners of this Festiva..

[25Horseplay]

You could try Festivamotorsport.com (best to call them) or place a want ad in our For sale forum here.

[elcamino1]

Take a look at one on a Aspire,probably the same!

[festivaWES]

i used to have one lying in the garage...don't know where it is at the moment though.

[mattswabb]

I bet the late 80's 323's are similar enough to use.

[Damkid]

i used to have one lying in the garage...don't know where it is at the moment though.

same here but i don't know where i last put mine

[FB71]

Take a look at one on a Aspire,probably the same!

yep, it is

[TealFestiva]

Proportioning valve skimatic/schymatic, oh heck...drawing?

well, been driving Festiva with leaking proportioning valve for couple of months now. No luck on finding a used one of either Festiva or Aspire in neighborhood/national junk yards. Considering taking it apart and replacing seals or whatever...but can't find a schematic of proportioning valve online or in my trusty Haynes book. Plus that means no transport while do the work....but can't keep adding brake fluid forever...anyone have an idea where to get a Schematic ?

[hawkdoc60]

Try one of the junkyards out on Highway 58 out by Suffolk and the Chesapeake airport. There are like six or eight of them. One of them should have a Festy or Aspire that you can get one off of.

I grew up in the Tidewater area of Virginia, that's how I know.

[Pu241]

Where is it leaking from?

[festivaWES]

i'll try and find my extra tonight.

[CharlieZ]

..Considering taking it apart and replacing seals or whatever...but can't find a schematic of proportioning valve online or in my trusty Haynes book.

Service manual says this part is not serviceable. My nature is to try it anyhow but usually the mfg. is right. Let us know. Take pix if you try or even get it apart.
CZ

[Mike McKown]

I took one apart on my '79 Chevy truck when it was almost new. It didn't leak but the rear brakes didn't do much of the work. Anyway, I gutted it and put it back together. The brakes worked great from that time on.

I don't know for sure how the Festiva part is made. There are different types for dual cylinder master cylinders. There the plain old distribution block with the sliding piston to contact the brake light switch in case of a leak. There's the combination valve. It will work like the distribution block but it will also shut off brake fluid to the end of the system that may be leaking. Then, there's a proportioning valve that simply adjusts the front/rear pressure. The festiva probably has the first example.

If it does, it may have a plug leaking in one end that you can remove and replace with a pipe plug. I'm not recommending you do this. Just that it might be a possibility. You can get into trouble messing with the brake system.

[CharlieZ]

From what I read, besides proportioning pressure between front and rear, the valve also plays a part in the crossed brake system where the left front and right rear is one circuit, and the right rear and left front is the other.
Anybody know this to be true? When I had a left front brake line failure, I know I lost all braking. If there is a crossed system, it sure didn't work in my 90 at that time.

[Mike McKown]

From what I read, besides proportioning pressure between front and rear, the valve also plays a part in the crossed brake system where the left front and right rear is one circuit, and the right rear and left front is the other.
Anybody know this to be true? When I had a left front brake line failure, I know I lost all braking. If there is a crossed system, it sure didn't work in my 90 at that time.

Some of those blocks are plumbed to feed cross corner, some front/rear.

I've had similar total brake failures three times over the years due to rusted lines rupturing. In every case, the total braking loss was because the master cylinder chamber that fed the end of the system that DIDN'T fail had already started blowing by but was masked by the dual system brake feature. No brake warning light prior to that either.

I'm going out on a limb here because I only know enough to be dangerous. I believe if you have a combination valve (warning light, distribution and proportioning), if you get a leak in the brake system, the valve will prevent total brake loss due to one chamber of the master cylinder losing pressure.

If you have a distribution valve (warning light and distribution) you can lose all braking ability due to a leak in one end of the system or the other. The distribution valve doesn't really split the systems in two like the combination valve.

I might be corrected on this.