Ok it started out with a very hard pedal, and past exsperiance told me it was the booster.So i replaced the booster and its not as hard but still not like it should be.Also the pedal is not coming all the way back up, there is alot of play in the pedal travel up by about a few inches.Im not losing any fluid so im stumped .

 

Is the new booster push rod adjusted properly? On the OEM booster the rod is adjustable. On some aftermarket boosters the rods are not adjustable - they just give you one long and one short rod. All else being ok, maybe thats the problem.

 

I've been doing my brakes obver in my 71 lately. What a pain. I have to replace the complete hard line to the passenger front. Anyways...

How long has it been since your last real brake job? I say this, because my calipers/hoses were newer but because it sat, they went bad. It wasn't even 10 years ago and a few thousand miles, and I'm buying all new stuff.

My suggestion to you is look closely at your brake hoses. I know its not a Vette, but I just replaced my 88 IROC's lines, too. They looked fine, but collapsed or swelled and/or didn't let the brakes up easily. They sat for too long and would grab but wouldn't let go. Replaced the hoses and they worked again.

Any slight pulling to either side?

 

Yea i checked the rod length and ajusted it till it just touched the master,but i had a hard time finding an ajustable push rod.My old one was to thick and the bottom of it looked like a exhaust valve.So by chance i looked at a 76 booster an sure enough it had the ajustable push rod so thats what i put on.Ill check the lines by bleeding the system ,but i just as might get the booster with the master on it just to eliminate that too.I was also thinking about the vacum,but i dont know whats exceptable amount ?

 

An engine in good shape should usually pull 16-20 inches of Hg at idle. Do you think you have a vacuum leak? A bad vacuum leak can reduce the effectiveness of your booster.

 

Im not sure,ill have to put the vac. gauge on it!

 

A vacuum leak big enough to make a difference on your vacuum gauge should be clearly audible with the hood up and engine idling. I don't know what year your car is, but if you have a vacuum actuated wiper door, there is an easy way to check for a slow leak. When I pull into the garage and stop the engine, I count slowly to 5, and then pull the auxilliary switch on the wiper door. If the wiper door opens, I don't have any major leaks. If it doesn't, then all of my vacuum has leaked out in the space of 5 seconds, which means I have a significant leak. I know I have a slow one right now, all the vacuum leaks out within 15-20 seconds, I'll look for it this winter (I already have some guesses of where it is). I've heard story of people being able to bring their headlights up after sitting overnight, but I have never had the system that tight on either of my Corvettes.

Anywho, a leak like mine shouldn't impact the operation of my brake booster, and mine seems to work fine. I suspect, though I don't know, that you would be getting bad mixture/missing in the engine from a vacuum leak before it would take down the operation of the brake booster. Maybe others with more experience can weigh in on that, but I would probably be looking elsewhere for the problem unless some devastating event has recently happened to your vacuum system.

 

You could still have air in the system or moisture. Did you bleed in this order, left rear then right rear then left front the right front. Lastly do you have the calipers on the rear with the two bleeder valves or one, two bleeders is a different process.

Bleed them again with help. Get someone to pump the pedal gently then hold it down while you release the bleeder valves.

One other thing you can check is the one way valve at the front of the master its where the hose from the block attaches.