Brake Proportioning Valve

[87Turbo-TWE4]

What exactly does this valve do and how can you tell when it's time to replace it?

 

[DailyDrifter]

The purpose of a prop valve is to hold off the pressure going to the front brakes until the rear brakes have engaged, if it didnt the car would do a nose dive everytime you hit the brakes and upset the balance of the car. They normally dont wear out, but the original cast ones had a recall. I believed they leaked through the casting itself. They now use a brass unit to replace the OEM one. GBodyParts.com Online

 

[87Turbo-TWE4]

Thanks for the info. That's what I needed.

 

[hemi8]

Also, if the valve senses a leak (drop in pressure) in either the front or the rear it will shut off flow to the leaking side and only allow the working side to function, which may save your life if you get a leak. This is why that little do-dad sticking out of the front of the combination valve has to be kept closed during bleeding operations, othewise it may shift to the front or the rear and will need to be reset.
Mike