I just upgrading the entire brake system on my 68. Front and rear disk, new (small) big block booster, master cylinder, proportioning valve, lines, braded SS hoses, everything. Complete matched system from MP Brakes.
I'm very satisfied with everything BUT... when I hit the pedal the first time to stop or slow down, the pedal feels fine, firm, and with the proper amount of feed back and travel. If I have to push the pedal the second time, within a very short time of hitting it the first time (traffic), I get a very hard pedal and very little travel. I really have to push on it to slow down. This has almost got me in trouble a couple of times.
I have checked really close for vacuum leaks. Vacuum is comming directly from the intake manifold, new (real) vacuum hose to the booster, check valve seems ok... I'm lost as to what it can be. I'm running 18 to 20 inches of mercury at idle.
Any of you guys got anything else for me to check?
Thanks for any input.
1968 pro-touring 350cid
1981 drag 454cid