Something is up with my brakes and I can't figure out what.

[86RangerXL]

I had a vacuum leak in my brake booster on my 86 ranger with the 2.9 causing the idle to drop when pressing the brakes, so I replaced the brake booster. Now, the brakes are so easy to press and sensitive that I thought I had no brakes at first cause I could literally press the brakes to the floor with 1 finger no problem and I jolt to a stop any time I touch them. They are WAY too sensitive. Before I replaced it, there was a good amount of force required to press them down, nothing excessive though. Instead of dropping rpms when pressing the brakes, now they go up, plus my idle is surging pretty badly (like from struggling to run rpms to 2k) I don't know what could be causing this and if the brakes are supposed to be this touchy, I'd rather have no power brakes. I replaced it with a Cardone 54-74009. Also, I doubt it has anything to do with the rest of my brake system considering I never touched any lines when replacing the brake booster.

 

[Uncle Gump]

I think the pedal now going to the floor has everything to do with your existing brake system.

Pedal height is really determined by three things.

Master cylinder push rod length. If it's too short the pedal has to travel to get to business.

Air in the hydraulic system.

Rear brake adjustment.

What does the pedal feel like with the engine off and no power assist? The pedal should be solid with minimal travel (an inch or two).

 

[86RangerXL]

I think the pedal now going to the floor has everything to do with your existing brake system.

Pedal height is really determined by three things.

Master cylinder push rod length. If it's too short the pedal has to travel to get to business.

Air in the hydraulic system.

Rear brake adjustment.

What does the pedal feel like with the engine off and no power assist? The pedal should be solid with minimal travel (an inch or two).

I adjusted the push rod on the new brake booster to match how much the old one stuck out. The pedal is solid with only a little bit of travel when its off. When its on, I have barely any movement before the brakes start working, its just the fact that there is absolutely 0 resistance the entire way once the engine is running. I can't test if there's any air in the lines right now cause I'm a bit busy. Also, I noticed the push rod on the new brake booster can be pulled completely out of the brake booster easily (The rubber seal connected to it to), while on the old one, it doesn't budge when you pull on it. The entire push rod even came upside down when I got the booster.

 

[Uncle Gump]

I'm still guessing your rear brakes are way out of adjustment.