So I have replaced the master cylinder, power booster, and both rear wheel cylinders. The car is a 1971 plymouth roadrunner with an aftermarket power front disk swap. (disks up front drums in rear). The kit uses what I believe to be a somewhat universal booster and GM master cylinder. The rear brakes are stock 8 3/4 drums. The pedal doesnt feel perfect in drive, but I havent had a problem with it being too soft, or having a lot of pedal travel. But the strangest thing happens when in reverse. Typically when I first get in my car and back out of the parking spot the pedal goes to the floor when I press it after ive moved a few feet. It does stop the car so I know it is applying some pressure, but I have to push the pedal extremely far and the pedal is very soft.
And when I put the car in drive and push the pedal twice it comes back up and the car stops fine and the pedal feels tons better. I checked the rear drum adjustment and the shoes are pretty tight against the drums. The master cylinder doesnt appear to be missing very much fluid at all. So I checked under the car, master cylinder, proportioning valves, steel lines, and rubber hoses, and I cant find any puddles or anything signifigant except some somewhat "wet" looking spots directly beneath the rear bleeding screws and around the connections on the rear wheel cylinders. Could air be seeping in through these spots and causing my symptoms? Anybody have any suggestions?
The steel brake lines were replaced with stainless lines 5 years ago, as well as the rubber lines.
Im thinking about having someone pressure bleed it with the master cylinder lid closed to find a leak if there is one. As always I appreciate any knowledge, experience, and helpful tips others have to offer. Full time college student working on this in my spare time.