Brake proportioning valve

[Enoch]

Now I have got to thinking about the braking system I have remembered that on the last car I built (Robin hood Project 2B) that the build called for the installation of the rear brake limiting valve. It's a valve that shuts off the flow of fluid to the rear brakes under heavy breaking so that the rears don't lock up. The early non ABS sierras had it, I don't think the later ones did. How does the IVA man view these things now? I have vague memories of my last car failing on an over braked rear but when I explained it had the valve, he checked it was there and then passed it. I think he drove it round the car park, slammed on the brakes and made sure it worked first. The valve does nothing on the rolling road as there is no inertia to cause the valve to shut. Anybody got any thoughts or comments on that? Just reading Adrian's post on having to change the rear cylinders kind of got me thinking. I can vaguely remember that the thing had to be set at a certain angle and changing that angle changed the sensitivity of the device.
Discuss