DirtyDaveW

My stock LT1 brakes were working fine but I opted to upgrade to the LS1 brake setup on the front (only)

Configuration:

• LS1 spindles
• New Autozone Calipers, pads, rotors and flexible brake lines
• No ABS is in use. Taken completely off the car. I have a proportioning valve.

Problem...
Pedal goes close to the floor before braking occurs and feels 'weak' in braking unless I double/triple pump the brake pedal


Bleeding procedures used so far...

• Mighty Vac at all four wheels 3 times.
• Buddy pumped the pedal while I cracked the bleeders one at a time
• 'Solo bleeder' kit that has a one way valve (btw.. absolute junk. Quit being one way in about 10 minutes)

Symptoms and analysis...

• No leaks anywhere
• Fluid topped off at all times
• Engine off, I can pump the pedal to have good pressure
• Engine on, I can pump the pedal to have good pressure
• Just read about this test..."with the engine off, pump pedal till you have plenty of pressure. Holding your foot on the brake with the pressure attained, start the engine. The pedal should drop a little bit"... However, when I do this, the pedal goes right to the floor.
• Also, when the engine is cold and I apply the brakes, the idle dips substantially. If I let go of the pedal, the idle resumes normality.
• I also have a line lock. If I press the brakes, I get a little braking action so I press the line lock and hold it. THEN if I press the brake pedal again, I have tremendous pressure on the brakes and it will lock up the front end if I push a little hard.
• If I pump up pressure whether the engine is off or running, it won't 'bleed' off and let the pedal slowly goto the floor. Note: this is not the same as the 'test procedure' I mentioned above where I pump the pressure then start the motor. Here, I'm meaning if the engine is off and I pump the pedal briskly for 10 times and then hold it, the pedal stays there. The same as when the motor is running and I press the pedal briskly for 10 times then hold the pedal pressure. It won't drop to the floor in that scenario.
• One other thing,.. when I was trying to mightyvac bleed the drivers side rear, I put about 20 psi of vacuum on it, then cracked open the bleeder screw. It would not drift down to zero psi but rather, stayed at 15psi at the lowest. I tried 4 more times (pumping to 20 then cracking the bleeder) but it never got below 15psi. When I finally pulled the hose off the bleeder, it whistled as the vacuum was finally used at atmosphere.

Do you have any suggestions?
Booster bad?
Master Cylinder bad?
Plugged brake line?

Thanks!

DirtyDaveW

Figured it out. The calipers were on with the bleeder screws facing down. They are supposed to have the bleeder screws on the top. Swapped the calipers, re-bled them and pedal pressure/braking is outstanding.