Brakes don't Bite Options

[bkrantz]

As part of my rebuild I completely replaced the brake system:
calipers and rear pressure valve rebuilt by PMB
new ATE 19mm master cylinder
new hard and flex lines
new disks and Porterfield R4-S pads

I went through many (many!) episodes of bleeding, with different methods. The pedal feels very firm from the first push, and does not pump up. Rear clearance is set at .004". I went through the PMB bedding process, and have driven around a bit.

But the braking force seems weak. When I get on the brake pedal, I do not feel any "bite". Another 914 friend drove the car and also agrees.

Any suggestions?

[robkammer]

All: This is all great info. So, an update, last Saturday I took the car out and braked (broke?) the living daylights out of it, 60mph to just about stop over and over and over. Got em really hot, got a little lockup on the right rear. Temps were high but my reader crapped out after two wheels.
Today, did a Motive pressure bleed, no fluid, just 15lbs air pressure in the jug. Enough to pinch the rotors a bit but not enough to blow the EZ fill lines apart. Didn't see any appreciable air bubbles.
Took a drive and did the same thing, got em hot, got lockup on only the right rear with the pedal right down at the floor.
Temps when I parked were in the 480's on the fronts and 380's on the rears.
I just don't understand the soft pedal with everything being new.
Some thoughts:
Should I 'exercise' the pistons to work the seals into the bore? Pull the rotors and have them turned? ( they were new less than 1500 miles ago, Pellican's better grade)
I put 195/60's on the car. Could the contact patch be too much for the brakes?
Some ideas: Exercise the calipers and bleed again.
Pressure bleed with the Motive and a full jug and run another quart through even though I'm into the fourth quart already.
Have the rotors cut to leave a pattern to help bed the Porterfields.

Going on two years and getting tired of screwing with these brakes.

Any input is welcome.
Thanks guys

[bbrock]

All: This is all great info. So, an update, last Saturday I took the car out and braked (broke?) the living daylights out of it, 60mph to just about stop over and over and over. Got em really hot, got a little lockup on the right rear. Temps were high but my reader crapped out after two wheels.
Today, did a Motive pressure bleed, no fluid, just 15lbs air pressure in the jug. Enough to pinch the rotors a bit but not enough to blow the EZ fill lines apart. Didn't see any appreciable air bubbles.
Took a drive and did the same thing, got em hot, got lockup on only the right rear with the pedal right down at the floor.
Temps when I parked were in the 480's on the fronts and 380's on the rears.
I just don't understand the soft pedal with everything being new.
Some thoughts:
Should I 'exercise' the pistons to work the seals into the bore? Pull the rotors and have them turned? ( they were new less than 1500 miles ago, Pellican's better grade)
I put 195/60's on the car. Could the contact patch be too much for the brakes?
Some ideas: Exercise the calipers and bleed again.
Pressure bleed with the Motive and a full jug and run another quart through even though I'm into the fourth quart already.
Have the rotors cut to leave a pattern to help bed the Porterfields.

Going on two years and getting tired of screwing with these brakes.

Any input is welcome.
Thanks guys

Man I feel for you. I'd be fed up too. Can't think of what would cause the soft brakes other than still have air in there somewhere, or the MC is just not doing its job. One fail safe way of eliminating air I've read that sounds like a giant PITA but is said to work is to pressurize the system and go around and crack open hard lines one at a time to make sure all air is out. Can't remember if there was a sequence. I'd guess MC and pressure regulator would be the prime suspect areas for trapped air.

Also, rear brakes shouldn't be locking if the regulator is adjusted and working properly but if it were me, I wouldn't chase that gremlin until figuring out the soft pedal. Could be related I suppose.

BTW, I'm running 195s on my car and can lock up the fronts on dry pavement.