I recently rebuilt my 91 NA's entire brake system- new rotors, SS flex lines, new MC, reman vacuum booster, rebuilt the rear calipers (stock, non vented) and upgraded to 4-piston front calipers (also rebuilt), Hawk pads all around with Ford High Performance fluid.
The system has been thoroughly bled 4 times now with no sign of air or leaks and the brakes work fine.
I followed Hawk's recommendations for bedding in the pads and the rotors/pads look good.
Made a few passes up and down Turkey Creek Rd (very twisty road in the foothills outside Denver) and there was no appreciable fade, so basically, the brakes are fine.

So, what's the question?
Well, I was hoping for better feel...it seems kinda mushy and soft to me and I'm not sure where to look for improvement or even if improvement is possible without extreme steps.
I see in the FSM that the models that originally came with the large front calipers have a larger bore MC and a different booster assembly and assume that maybe replacing these two items might make a difference but would it be worth the cost?

Is the large bore MC a direct replacement for the original NA unit or are the hardlines ( a real PITA to reroute) different as well?
If you've upgraded to 4-piston calipers, what did you do about the rest of the system?

I just bought the car in December and the stock rotors/pads were absolutely thrashed so I have no good baseline to measure against...maybe what I have now is as good as it gets (with stock components) and I'll just learn to love 'em- I'd just be interested in other folks thoughts...

 

thats about all you can do, you have redone almost the whole system, other than the lines. I would do a rebleed soon and see if that helps. Good Luck!

 

I'm not familiar with SS flex lines. But I know your brake lines must be very capable if standing up to large amounts of pressure

 

I went through 3 reman brake boosters before I found one that worked well. And I ended up not using the reman, but a working stock one from a parts car. The problem I was having on my car was.... No matter what I replaced, upgraded, or fixed, the brakes always seemed a little weak... not squishy, squeeky, or fading.... but just felt weak. No matter how many times I bled the thing, no matter how nice my braided hoses were....

I replaced the booster, same thing......... took months to get myself to try another one... Swapped it out, same thing... figured it wasn't that. But, for good measure, I got another one from a junk car... worked awesome. Brakes felt great. Tons of stopping power, almost no effort needed to stop the car... didn't bottom out (or atleast FEEL like it was bottoming out).

Not sure if my experience is valid or reproducible with other people, but just my experience.

You might also want to make sure your booster is getting a good vacuum.

 

Did you bench bleed the master cylinder?

 

i forgot to tell to you to see if you changed the check valve. Its a rubber hose coming off the booster, about 5 or so inches long. That could help too.

 

Actually, it's only the Turbo's that got the bigger MC, but they also got a stronger booster, so the feel is likely to be about the same. I upgraded my car from single to 4 piston brakes and they feel nice and stiff.

Another thing to do is make a brake master cylinder brace. It helps by reducing firewall flex.

With all new components there's likely to be some air trapped in the system at some high point which can take a lot of work to get out.