A Body Disc Brake Swap 101

spencer0731 said

I converted my 70 340 duster drum brakes to the 74 big brake set up. I also bought a new mastercylinder/power brake booster kit. I had no problem doing the swap but, now, no matter what i do, i can't get any pedal. I can bleed and bleed but, i still have to push the pedal to the floor to even consider stopping. I am not sure if i have the right proportioning valve or not. does anyone have a picture of the 74 disc brake proportioning valve? i have like 4 different types. I can't think of anything else it could be unless i have the brake lines hooked up to the wrong sides of the proportioning valve. can you get a diagram of how to do it right?

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Did you bench - bleed the master cylinder, prior to installation?

Also, sounds like you have air somewhere in the system. Did you use new brake hoses, and as previously mentioned - check to see what master cylinder application you have, i.e. the bore size.

You probably already know this, but all factory built 1970 Duster 340s came from the factory with the Kelsey-Hayes disc brakes as standard equipment.
So what you are dealing with - is a car that either was a /6 or 318 car, or someone lifted the original discs. The VIN for all 1970 factory Duster 340s would start: VS29H0* where H denotes the factory 340 build, and zero(0) is the model year.