[Scarebird]

Scott, it would have to be. Let's pretend that if a car's brake system was working correctly, each circuit (front and rear) would use 1 cubic inch of displacement from start to full engagement.

In my illustration, I assigned rear to red, green to front. In the top diagram, we have the single reservoir master. Both frnt and rear fluid of course is intermixed, and the cylinder has a single outlet leading to simple distribution block. The lower diagram represents a simple monobore dual circuit setup- with a fixed single piece piston.

As you can see, to empty the single master, your would need 2 inches of stroke, while the dual would only take 1" to accomplish the task. Of course, the dual would also take twice as much force, most likely achieved by leverage at the brake lever, as lever arc travel would be a constant.

The true test would be to poll some of my customers who have switched from single to dual without lever pin movement.

[71firebird400]

ScottK- the pedal feels normal; it doesn't drop excessively or feel spongy. I think I might invest in the pressure gauge as I too feel that by going with power brakes it will just "mask" the problem rather than solve it.

[sts]

Yes, using a power booster would only be masking the problem. It's hard pedal, not a graidiant solid mush as brakes are supposed to be.

I mentioned it back at the begining and I think that other people have mentioned it. Have you checked the tension on the brake rod? You haven't mentioned the results of this test, I'm not a mindreader, so I can only guess that you haven't tried this troubleshoot.

It needs zero lash, meaning almost/slightly flopping around. If there is enough pressure on the rod, it causes the m/c cups to cover the residgual port, a hole that allows the fluid to bleed off pressure when you let off the brakes. Covering the residgual port will give symptoms as you describe.

If you have actually loosened the rod until it slightly flops around, and it doesn't solve the problem, you can rule out this as a problem. But unless you actually loosen up the rod until it flops around, you cannot be positive that this isn't the problem. In the many years of being a proffesional mechanic, the biggest problem I have seen with professionals and amatures is that they do not troubleshoot with a go/no-go. You cannot say that's okay. You have to actually test setting it up with before change and after change. If you don't use that approach always, you're pissing in the wind, something that a lot of professional mechanics do because they will not take the time to verify correct operation of components.

Maybe an idiot would have a problem with setting the rod so that it flops around, but you show an abundance of common sense, so you probabally understand the definition of zero loas plus slop. If the rod is set at zero lash with slop, it cannot fall out. If you haven't tried it, you cannot rule it out as not causing the problem. Loosen the rod until it flops around and test the brakes. If it doesn't slove it, set it back where it was. If it solves the problem, and you cannot stand the thought of the rod flopping around, tighten it up some until the point just before it causes the hard pedal.

[Scarebird]

an excellent point- especially with power brakes.

[71firebird400]

I just ran downstairs and checked the linkage between the pedal and master cylinder; from just looking and feeling it; it felt somewhat "tight" (no slop). Perhaps this is the root of all these problems (I would be overjoyed!). It 11 pm here so I don't want to jump to any conclusions; but I'm definetly taking a closer look tomorrow. If it were in fact to tight how would I go about loosening it? Thanks!

[71firebird400]

Good News! I adjusted the brake pedal to have a little bit of slop and took the car out for a test drive. After about 3-4 blocks I noticed the brakes really starting to get stronger; now the car will skid the rear wheels (although the left locks up before the right; but thats another issue I'll have to work out). Overall the brakes improved quite a bit; now I want to bleed the system one last time and possible replace the front calipers; the reason being that with the brakes improved so much I notice things I couldn't before (the car wanders just a slight amount under heavy stopping). I would like to say THANK YOU to STS, Scarebird, ScottK, and anyone else who contributed! It's amazing that you guys stuck with it over the past months getting this thing figured out.

Mark

[Scarebird]

good to hear! one of my customers may have had the same issue...