Guys:

I have been reading a large number of post related to changing the combination valves in 3rd gens. I want to make sure that people understand there is a major safety roll that the valve plays in the braking system.
The combination valve does 3 things.
1. It reduces pressure to the rear brakes to prevent premature lock up.
2. It has a small metering effect that delays the application of the front brakes until the rears "catch up." This is mainly a disk drum issue.
3. If there is a significant pressure differential between the front or the rear systems it closes off the low pressure system which therefore allows the opposite system to still function.

What this means is that if your remove or bypass the combination valve and you break a line or have a caliper fail you will loss all brakes. i.e. the peddle will go to the floor. The fact that you have a dual master cylinder means nothing from a safety standpoint without the combination valve in the system.

I just wanted to make sure that everyone was aware of this before they started making changes to the brake system.