Okay, I have bled brakes, replaced parts, bled brakes, replaced parts, have the brake shop bleed the brakes, replaced more parts. I am sick and tired of this problem. My 1987 NA car is very slow to stop unless you absolutely stand on the brake pedal. Replacing all those parts has not changed the stopping distance or feel AT ALL.

All the parts listed below are new and have been changed since I discovered this problem. I have properly bled the system upon changing the rear calipers using both upper and lower bleeder valves as well. The brake shop recommended using a brand new master cylinder instead of a remanufactured one and that had no effect.

The only thing I can think of is that somehow the flexible or hard lines are allowing air in. I can not dectect any fluid leaks at the connections in the fender wells, at the calipers, or at the master cylinder. Brake pads and rotors are in almost brand new condtion. If any one has any suggestions, please post.

Parts replaced:
Brake booster
Master cylinder (once with a remanufactured, now has a brand new one)
Front calipers
Rear calipers

 

There is a "check valve" located in the vacuum line which connects from the booster to the engine. When the line is disconnected from the booster you should be able to blow air into the tube towards the engine and "not" vice versa. If not, then the valve is either clogged or the valve or tube is backwards or the valve is nonexistent.

 

Fabbing up new hard lines is pretty simple (and not very expensive) but if they were the problem, you'd still be getting air through the bleed nipples and since you didn't mention that I assume you're not.

Looking at the list of parts you've already replaced, the only thing left is the check valve in the booster vac line.
Or even the vac line itself.

Might give those two things a look.

 

I will try that when I get home this evening, but I am not sure that is the problem either. The pedal is not rock hard at any point before, during, or after bleeding which I thought is indicative of a bad booster/check valve. Something else I forgot to mention. With the car off and bleeding the pedal is firm after a point, when the car is turned on and taken to test drive, it feels much worse, spongy even. It sinks a lot further than when the car is off.

 

Does the car have 4 piston calipers up front or single piston?
Is the car originally an N/A or a Turbo?

I recall on this site somewhere before... N/A's have a smaller MC than the Turbo's. Even if they came with 4 Piston setup like the GXL's.

 

Did you lengthen the brake booster pushrod slightly so that the brakes "catch" with less pedal travel?

 

Okay, check valve only allows air passage away from the booster as stated above. The car is NA and always has been. Has stock single pistons in the front. I have not tried to adjust any push rods for this reason. Before this problem, the car stopped just fine and the pedal felt fine. It sat for a while and when I went to drive it again it started giving me the problem I am dealing with now.