The PO kept the original drum/shoe configuration on the front, but put drum/shoes from a ’69 Camaro on rear, and replaced original master cylinder with one from a ’54 Ford Club (kept it in the under floor configuration). Five years ago I replaced all the shoes and wheel cylinders and have driven less than 3,000 miles since then. It never has stopped very well but it was adequate.
However few months ago I adjusted one of my front wheel cylinders, and started noticing that I had to pump my brake pedal a few times to build pressure/stopping power. Noticed about the same time that I had a leaky master cylinder. So this week I replaced the MC with a new one (to match the ’54 Ford Club MC). I properly bench-bled the new master cylinder and bled the lines thoroughly (pushed about 20 oz of brake fluid thru) but still have the same problem with needing to pump the brakes to build pressure. No leaks I can find anywhere.
At the bottom of the master cylinder reservoir I have two holes to the piston cylinder; one about 3/16” diameter and the other just a pinhole; the larger hole is near the start of the piston stroke–the pinhole is toward the end of the stroke. Observing piston travel with the reservoir cap off, a few tiny bubbles come up from the pinhole on each return stroke. My brake lines hold only about 3 oz, so with proper bench bleeding and pushing 20 oz thru I can’t imagine I didn’t get all the air out of the system.
Any ideas why I still have to pump up the brakes?
