http://www.gofasst.us/brake_proportioning1.htm

I did it on a 3rd gen Camaro with 4 wheel discs, the rear brakes would lock up instantly! I just removed the spring left the plunger in, and reassembled it. You don't need to buy the $49. valve from his friend. If you are going to spend $49. on a new valve, why not get one that works right without having to modify it?

I believe there is no proportioning done by that valve, it's just a pressure limiting valve that prevents more pressure to the rear once a set point has been reached. Keep in mind I tested a 4 wheel disc valve from an 89 IROC, not this exact one.
David

Thanks David,
I just found this link in an OLD email and wondered why anyone would want to do that. It's an old mod anyway....maybe before the aftermarket had better options.

Joe I was going to suggest the author was playing with fire. Most cars by design will nose dive and transfer weight to over the front wheels. In effect this allows the brakes to keep from locking just a bit longer. As the rear gets lighter you don't want the rear brakes to lock so the pressure to the rear should be reduced. If the mod worked as stated the car probable locked the wheels sooner making it take longer to stop.

As long as I have played with cars the rears always take at least twice as long to wear out compared to the front. Even prices reflect this with the front pads being 1/3 less than the rear typically.