A couple of months ago I decided to replace the brake system in my 71. Since I bought the car back in October it never stopped well. Pedal travel always went almost to the floor and it would not lock up the brakes. I made the decision to convert to manual brakes. My engine only makes 12” of vacuum at idle. I didn’t want to mess around with hydro boost or add a vacuum pump.
I have since done the following:
installed all new factory style hard brake lines and stainless steel braided flexible lines from inline tube.
installed new D52 calipers and rotors from right stuff detailing.
installed new wheel cylinders and all new drum components. AC Delco wheel cylinders, power stop drums and shoes.
installed a new combination valve PV102 from inline tube.
installed a Wilwood 15/16” bore master cylinder with a 10psi residual pressure valve coming off the master feeding the rear circuit.
I have 3/16” lines from the M/C plumbed down to the combination valve both front and back circuits. All other hardline is OEM size.
This is the third master cylinder I’ve put in. I started with a universal GM 1” bore M/C but snapped a fitting off in it trying to stop a leak. The second M/C was a 1” bore corvette style, but it was blown out of the box with leaky piston seals. Tired of the Chinesium repop junk, I called Wilwood, told them what I had and installed what they recommended.
So far this car has defeated everything I know about braking systems. I cannot get a good solid pedal. I have literally flushed a gallon of brake fluid through the system in attempt to get all the air out. As far as I can tell, there is no air in the system. I’ve vacuum bled, gravity bled, and pump bled the system multiple times. I move fluid to all four corners. Both calipers and wheel cylinders actuate as they should. The drums are all set as they should be with all the parts and pieces in the right places. The parking brake is disconnected though. The calipers are square to the rotors (best that I can tell) and their pistons are free and moving.
Yesterday, I plugged both outlets on the master cylinder and pedal pressure is solid. I reconnected just the front part of the system, bled it and the pedal was spongy. I then did the same to the rear system. Disconnected the front, reconnected the rear, bled it and the pedal was spongy. With both front and back circuits connected the pedal is spongy and feels like there’s very little pressure.
I have no clue what to do next. I was hoping maybe someone here has some ideas on what to check next.
Sorry about the long post. I’m really at my wits end with this car.
