Spongy brakes, 914-4 brakes won't firm up??! Options

[Gearren]

I've had it! I have done everything to the brakes on my car, and I can't seem to get them to stop the car with authority. Best I get is a reluctant coast to a stop. Hardly suitable for street use! I have owned the 73 2.0 since new, and have kept it in the garage since 85. Brakes have always been weak, so as I starterd on the quest to revive the car, the brakes were top on the list. I have rebuilt both front and rear calipers, turned the rotors, new pads, new M/C (17mm), bled the m/c, bled the prop valve, and bled the system at least 10 times! I still have weak/spongy brakes! I want to keep the car stock, however I am tempted to remove the prop valve to see if it is the culprit. Any ideas or suggestions would be appreciated??

[mike_the_man]

I'm in about the same boat as you. I would recommend replacing the flex lines. If they haven't been replaced since 83, that could very well be your problem. I personally don't like the SS lines, but opinions vary. Next, try replacing the proportioning valve with a T, just to eliminate that as a problem. If that doesn't fix your problem, check each caliper seperately. Here is how I did that:

Either by a metric bolt that you can use as a plug, or go to your FLAPS and buy some bubble flaired brake lines. Cut them in half and compress the lines and roll them so that it seals it up. You'll need 4 of them. Now, disconnect the hard line that connects the caliper to the flex line at each corner, and use your plugs in the end of each flex line. Stomp on the brake pedal. It should be rock solid, or very close. If not, you probably have leak somewhere.

Now connect the rear passenger side caliper. Bleed it till you get a rock hard pedal. Now connect the rear drivers side caliper, bleed. repeat for each caliper. If you hit a caliper and can't seem to get a solid pedal, then there's your problem. Thats what ended up being my problem. My front drivers side caliper was sticky, and I couldn't seem to unstick it. I ended up replacing the front with BMW calipers, and they seem to work much better.

I hope this helps, or at least makes sense!