I put disc brakes on Ford 9 rear. With 2 lb. valve inline front and rear . Adjustable proportional valve towards rear after the master cylinder. Disc brake kit has Eldorado 79-85 disc brakes with emergency brakes. Bled system adjusted emergency brakes which require a special tightening of the brake pistons to the rotor. Start engine and brake pedal goes right to the floor. Can't come up with what I may be doing wrong. Bled system a number of times, even replaced the 7"brake booster. Master cylinder has about 700 miles on it.
Do you have any free play between the pedal and the booster, or between the booster and master cylinder?
Adjusted the distance between the pin in master cylinder and booster, maybe 1/16 spacing. Pedal is attached to the booster rod with a rod eye.
I keep a couple of brake line fittings around that I Have plugged to check which end of the system has the problem
Check the rod adjustment between the master and the booster. That adjustment being too long will cause the pedal drop like you are describing. Good luck!
This can be temporarily done by putting washers on the studs on the booster that hold the master cylinder. If adding in a pair, or a few pairs of washers alleviates the issue, the thickness of those washers is the amount that needs to be removed from the booster push rod.
I fought a 4 wheel disc setup for months with the pedal going to the floor. Finally removed the prop valve from the system and it stopped like a new car... The restriction was making the master cyl byp*** internally and not actually do anything.
What is the master cylinder from? In going from drum to disc on rear, it may need a check valve removed.
Do yourself a favor GO to CPP if they have one for your Vehicle and get the correct set-up you need then you know it is CORRECT and SAFE--
The Jalopy Journal
