I have converted a power brake all drum car to front disc. In addition I replaced the automatic tranny with an A833 four speed which required me to install different pedals. The 383 engine has been juiced up via an Edelbrock top-end kit. The cam that came with the kit is pretty strong and reduced my idle vacuum to 10", which is normal for this package per Edelbrock. So now I have a vacuum pump on the vehicle that is producing around 22" for the booster. The single piston wheel/disc kit was put together by ABS(Amer. Brake Systems) in Calif.- purchased from Classic Industries. This kit was suppose to be "bolt on" w/no mods. necessary. Used standard single diaphram booster and master, added a combination valve assemb. that came with the disc kit, all new lines and hoses.
PROBLEM: I haven't been able to get any more than 750 psi reading at the wheels, not enough to operate the front disc. Even tried a different booster/master and same thing. Haven't tested the combination valve as yet because I'm not sure that this would affect the overall pressure? Have played with the pedal linkage with no results. Anyone out there who might have any idea as to what's going on? All suggestions considered! Thanks!

 

Can't help with specifics.

You are measuring pressure before the combo valve?

You might need a smaller bore master cyl?

The front brakes HAVE to do "something" at that pressure, do you mean to say they are doing nothing? Something plugged, defective master? Did you bench bleed the master? What sort of pedal does it have?

 

All wheels are barely engaging at this time, approx. 15% of what it should be. The master is a Dorman that has a 1 1/32" bore. The front disc pads are not engaging the rotors evenly; dragging on the outside but not on the inside. Thanks!

 

?? You do have the bleeder nipples on the top ?