I have a 1966 Mustang, 289, Auto. I've installed a front disc brake conversion, and I can't get rid of a very soft pedal. It is a kit with front discs and calipers as well as a new booster, proportioning valve, and m/c. No leaks in the system. I've bled, and bled the wheel cylinders over and over. I've pulled the m/c and bench bled that multiple times without any change. I've adjusted the push rod length about 1/16" off the m/c piston at rest. Manifold vacuum pressure runs around 20at idle. I've adjusted the rear brakes to drag slightly. I've adjusted the at rest pedal position super high so I the pedal doesn't hit the floor, but the pedal travel is soft. On top of the extreme pedal travel the brakes don't really work that well. I've test driven the car and it just doesn't stop well. Even at a crawl in my driveway I can't get the brakes to lockup, or even close. I see quite a few past posts from folks with similar issues, but I don't see any with resolution. I see mention of trying to relocate the pushrod connection pin on the brake pedal. Do I need to look into that some more? I can see how that might make it easier or harder to push the pedal but since I can't get what I think is a good function of the brakes I can't see that being my issue. I've seen lots of comments as well about MC piston size and caliper piston size. Certainly I would think a kit sold specifically for my car from a reputable Mustang parts supplier would have that all worked out, right?
One thought had was questioning the throw or travel of the push rod from the booster into the m/c. Without the m/c connected the pushrod from the booster travels about 3/4" forward when the pedal is pushed. When I bench bleed the m/c I can press the piston in about 1 1/2". Does that sound right? I wouldn't think I would be depressing the m/c piston the entire 1 1/2" with the booster pushrod but maybe more than 3/4"? How would you even adjust that? Any thoughts are appreciated?
One thought had was questioning the throw or travel of the push rod from the booster into the m/c. Without the m/c connected the pushrod from the booster travels about 3/4" forward when the pedal is pushed. When I bench bleed the m/c I can press the piston in about 1 1/2". Does that sound right? I wouldn't think I would be depressing the m/c piston the entire 1 1/2" with the booster pushrod but maybe more than 3/4"? How would you even adjust that? Any thoughts are appreciated?
