Technical 56 F100 brake problems (CPP booster)

hey guys, I've been having quite a few problems with the brakes on my 56 F100. I completely restored the truck, went with a CPP kit, discs up front, power booster on frame, and discs on the rear. All new 3/16 hard lines, residual 2lb valves in both front and rear lines, CPP disc/disc proportioning valve. I've adjusted the pedal out as far is it goes for more pedal travel. I've bleed the brakes numerous times with dot 4 fluid (as per CPP instructions), bench bled the master cylinder 5 times now, and still can't seem to get a "firm" pedal. I installed a 8.8 rear end out of a mustang about a month back, and got the brakes working as best as they ever had, which still doesn't have a great pedal. I've bleed them all sorts of ways, hand pump, vacuum pump, and the old school way having someone pump the brakes. Went through gallons of brake fluid too. There are no visible leaks. If I bleed the brakes, I have a decent pedal, but if it sits for a few days the pedal goes soft, all the way to the floor. I'm completely stumped, and CPP hasn't been much help.

Any help is greatly appreciated

Thanks

 

Sounds like a bad M/C....

 

Chopped51 is right. The M/C is the only 'bypass' that is built in. That is the place to look...

 

I wonder if I should go with another master cylinder from CPP or try another brand? I've read lots of negative stories on CPP's brake components online

 

Also, I don't have my rear parking brake hooked up. Do I have to have it hooked up to get the rear brakes working properly?

 

Do you lose fluid when the pedal dies? If you have a bypassing master you can usually tickle it so it bypasses, no fluid loss. I'd still look for leaks in the system.

The problem with CPP and other kits, one size fits most. You have a menagerie of parts that was never meant to work together.

 

I dont believe I lose fluid when the pedal dies. If I bleed the brakes, right away I get a firm pedal. I'd say a 7 on a scale of 1-10. I'm not sure really what to expect, i'm use to driving newer cars with hydroboost brake systems. And right after wards of bleeding, it does stop really well. After the first inch of travel in the brake pedal, it grabs and starts stopping. But after it sits, the pedal will go dead the first 3 inches or so, and still stop, but nowhere near as good, and travels all the way to the floor.

I get what you're saying about CPP. I've read alot of forums on Trv-five chevys and ALOT of people had this problem with the master cylinders. I may call CPP one more time, along with a few others and try to find another master cylinder that is not CPP.

I will put the truck on the lift this evening and inspect for leaks one more time.

 

If the components are right, you should expect good firm brakes. Nothing weird.

 

So after speaking with Wilwood Brakes, and measuring the diameter of the pistons on my calipers, they seem to think my master cylinder is too small (1" bore). I purchased a 1.125" wilwood master cylinder, along with a adjustable proportioning valve. We will see what happens in the next few days.

 

It still sounds like the CPP master was bypassing. And you get greater fluid capacity with the bigger master. Keep at it, the only way to solve the problem. Anything Wilwood is top notch.