Is my booster bad?

[matt71vh]

Hi Guys. I have a 72 dart with stock power disk brakes. My problem is twofold.

When I brake at a light I notice that if I press hard on the peddle while stopped the idle lopes and gets rough as if the engine has sprung a vacuum leak. If I ease off the pedal the idle turns normal again.

Second, I had to brake hard on the freeway the other day and everything was working great until I had to really step on it. It seems once I passed a point in the pedal travel the brakes became rock hard and would not give me extra stopping force. Scared the $*#@ out of me.

Thoughts??

Thanks

 

[TrailBeast]

I could be a split in the diaphram causing an air leak at that pedal travel.
Usually they will lope a little as you are pressing and releasing the pedal, but not the entire time you have the brakes pushed.
Chk the fluid and make sure it's full as one empty chamber can also cause the lack of braking on one end.